Python: request processing in multiple threads.

This closes #459 issue on GitHub.

13 files changed, 992 insertions, 497 deletions

diff --git a/src/nxt_application.h b/src/nxt_application.h
index cb49a033..7f8ec1ba 100644
--- a/src/nxt_application.h
+++ b/src/nxt_application.h
@@ -51,6 +51,8 @@ typedef struct {
     nxt_str_t  path;
     nxt_str_t  module;
     char       *callable;
+    uint32_t   threads;
+    uint32_t   thread_stack_size;
 } nxt_python_app_conf_t;
 
 
diff --git a/src/nxt_conf_validation.c b/src/nxt_conf_validation.c
index b44509e3..97a13e38 100644
--- a/src/nxt_conf_validation.c
+++ b/src/nxt_conf_validation.c
@@ -95,6 +95,10 @@ static nxt_int_t nxt_conf_vldt_return(nxt_conf_validation_t *vldt,
     nxt_conf_value_t *value, void *data);
 static nxt_int_t nxt_conf_vldt_proxy(nxt_conf_validation_t *vldt,
     nxt_conf_value_t *value, void *data);
+static nxt_int_t nxt_conf_vldt_threads(nxt_conf_validation_t *vldt,
+    nxt_conf_value_t *value, void *data);
+static nxt_int_t nxt_conf_vldt_thread_stack_size(nxt_conf_validation_t *vldt,
+    nxt_conf_value_t *value, void *data);
 static nxt_int_t nxt_conf_vldt_routes(nxt_conf_validation_t *vldt,
     nxt_conf_value_t *value, void *data);
 static nxt_int_t nxt_conf_vldt_routes_member(nxt_conf_validation_t *vldt,
@@ -489,6 +493,14 @@ static nxt_conf_vldt_object_t  nxt_conf_vldt_python_members[] = {
     }, {
         .name       = nxt_string("callable"),
         .type       = NXT_CONF_VLDT_STRING,
+    }, {
+        .name       = nxt_string("threads"),
+        .type       = NXT_CONF_VLDT_INTEGER,
+        .validator  = nxt_conf_vldt_threads,
+    }, {
+        .name       = nxt_string("thread_stack_size"),
+        .type       = NXT_CONF_VLDT_INTEGER,
+        .validator  = nxt_conf_vldt_thread_stack_size,
     },
 
     NXT_CONF_VLDT_NEXT(nxt_conf_vldt_common_members)
@@ -1329,6 +1341,52 @@ nxt_conf_vldt_proxy(nxt_conf_validation_t *vldt, nxt_conf_value_t *value,
 
 
 static nxt_int_t
+nxt_conf_vldt_threads(nxt_conf_validation_t *vldt, nxt_conf_value_t *value,
+    void *data)
+{
+    int64_t  threads;
+
+    threads = nxt_conf_get_number(value);
+
+    if (threads < 1) {
+        return nxt_conf_vldt_error(vldt, "The \"threads\" number must be "
+                                   "equal to or greater than 1.");
+    }
+
+    if (threads > NXT_INT32_T_MAX) {
+        return nxt_conf_vldt_error(vldt, "The \"threads\" number must "
+                                   "not exceed %d.", NXT_INT32_T_MAX);
+    }
+
+    return NXT_OK;
+}
+
+
+static nxt_int_t
+nxt_conf_vldt_thread_stack_size(nxt_conf_validation_t *vldt,
+    nxt_conf_value_t *value, void *data)
+{
+    int64_t  size;
+
+    size = nxt_conf_get_number(value);
+
+    if (size < PTHREAD_STACK_MIN) {
+        return nxt_conf_vldt_error(vldt, "The \"thread_stack_size\" number "
+                                   "must be equal to or greater than %d.",
+                                   PTHREAD_STACK_MIN);
+    }
+
+    if ((size % nxt_pagesize) != 0) {
+        return nxt_conf_vldt_error(vldt, "The \"thread_stack_size\" number "
+                             "must be a multiple of the system page size (%d).",
+                             nxt_pagesize);
+    }
+
+    return NXT_OK;
+}
+
+
+static nxt_int_t
 nxt_conf_vldt_routes(nxt_conf_validation_t *vldt, nxt_conf_value_t *value,
     void *data)
 {
diff --git a/src/nxt_main_process.c b/src/nxt_main_process.c
index e4ec8b57..16c405ac 100644
--- a/src/nxt_main_process.c
+++ b/src/nxt_main_process.c
@@ -197,6 +197,18 @@ static nxt_conf_map_t  nxt_python_app_conf[] = {
         NXT_CONF_MAP_CSTRZ,
         offsetof(nxt_common_app_conf_t, u.python.callable),
     },
+
+    {
+        nxt_string("threads"),
+        NXT_CONF_MAP_INT32,
+        offsetof(nxt_common_app_conf_t, u.python.threads),
+    },
+
+    {
+        nxt_string("thread_stack_size"),
+        NXT_CONF_MAP_INT32,
+        offsetof(nxt_common_app_conf_t, u.python.thread_stack_size),
+    },
 };
 
 
diff --git a/src/python/nxt_python.c b/src/python/nxt_python.c
index 01534a47..26a6f093 100644
--- a/src/python/nxt_python.c
+++ b/src/python/nxt_python.c
@@ -15,8 +15,20 @@
 #include NXT_PYTHON_MOUNTS_H
 
 
+typedef struct {
+    pthread_t       thread;
+    nxt_unit_ctx_t  *ctx;
+    void            *ctx_data;
+} nxt_py_thread_info_t;
+
+
 static nxt_int_t nxt_python_start(nxt_task_t *task,
     nxt_process_data_t *data);
+static int nxt_python_init_threads(nxt_python_app_conf_t *c);
+static int nxt_python_ready_handler(nxt_unit_ctx_t *ctx);
+static void *nxt_python_thread_func(void *main_ctx);
+static void nxt_python_join_threads(nxt_unit_ctx_t *ctx,
+    nxt_python_app_conf_t *c);
 static void nxt_python_atexit(void);
 
 static uint32_t  compat[] = {
@@ -44,11 +56,15 @@ static wchar_t            *nxt_py_home;
 static char               *nxt_py_home;
 #endif
 
+static pthread_attr_t        *nxt_py_thread_attr;
+static nxt_py_thread_info_t  *nxt_py_threads;
+static nxt_python_proto_t    nxt_py_proto;
+
 
 static nxt_int_t
 nxt_python_start(nxt_task_t *task, nxt_process_data_t *data)
 {
-    int                    rc, asgi;
+    int                    rc;
     char                   *nxt_py_module;
     size_t                 len;
     PyObject               *obj, *pypath, *module;
@@ -124,9 +140,17 @@ nxt_python_start(nxt_task_t *task, nxt_process_data_t *data)
 
     Py_InitializeEx(0);
 
+#if PY_VERSION_HEX < NXT_PYTHON_VER(3, 7)
+    if (c->threads > 1) {
+        PyEval_InitThreads();
+    }
+#endif
+
     module = NULL;
     obj = NULL;
 
+    python_init.ctx_data = NULL;
+
     obj = PySys_GetObject((char *) "stderr");
     if (nxt_slow_path(obj == NULL)) {
         nxt_alert(task, "Python failed to get \"sys.stderr\" object");
@@ -216,35 +240,50 @@ nxt_python_start(nxt_task_t *task, nxt_process_data_t *data)
 
     nxt_unit_default_init(task, &python_init);
 
+    python_init.data = c;
     python_init.shm_limit = data->app->shm_limit;
+    python_init.callbacks.ready_handler = nxt_python_ready_handler;
 
-    asgi = nxt_python_asgi_check(nxt_py_application);
-
-    if (asgi) {
-        rc = nxt_python_asgi_init(task, &python_init);
+    if (nxt_python_asgi_check(nxt_py_application)) {
+        rc = nxt_python_asgi_init(&python_init, &nxt_py_proto);
 
     } else {
-        rc = nxt_python_wsgi_init(task, &python_init);
+        rc = nxt_python_wsgi_init(&python_init, &nxt_py_proto);
     }
 
-    if (nxt_slow_path(rc == NXT_ERROR)) {
+    if (nxt_slow_path(rc == NXT_UNIT_ERROR)) {
         goto fail;
     }
 
+    rc = nxt_py_proto.ctx_data_alloc(&python_init.ctx_data);
+    if (nxt_slow_path(rc != NXT_UNIT_OK)) {
+        goto fail;
+    }
+
+    rc = nxt_python_init_threads(c);
+    if (nxt_slow_path(rc == NXT_UNIT_ERROR)) {
+        goto fail;
+    }
+
+    if (nxt_py_proto.startup != NULL) {
+        if (nxt_py_proto.startup(python_init.ctx_data) != NXT_UNIT_OK) {
+            goto fail;
+        }
+    }
+
     unit_ctx = nxt_unit_init(&python_init);
     if (nxt_slow_path(unit_ctx == NULL)) {
         goto fail;
     }
 
-    if (asgi) {
-        rc = nxt_python_asgi_run(unit_ctx);
+    rc = nxt_py_proto.run(unit_ctx);
 
-    } else {
-        rc = nxt_python_wsgi_run(unit_ctx);
-    }
+    nxt_python_join_threads(unit_ctx, c);
 
     nxt_unit_done(unit_ctx);
 
+    nxt_py_proto.ctx_data_free(python_init.ctx_data);
+
     nxt_python_atexit();
 
     exit(rc);
@@ -253,6 +292,12 @@ nxt_python_start(nxt_task_t *task, nxt_process_data_t *data)
 
 fail:
 
+    nxt_python_join_threads(NULL, c);
+
+    if (python_init.ctx_data != NULL) {
+        nxt_py_proto.ctx_data_free(python_init.ctx_data);
+    }
+
     Py_XDECREF(obj);
     Py_XDECREF(module);
 
@@ -262,7 +307,195 @@ fail:
 }
 
 
-nxt_int_t
+static int
+nxt_python_init_threads(nxt_python_app_conf_t *c)
+{
+    int                    res;
+    uint32_t               i;
+    nxt_py_thread_info_t   *ti;
+    static pthread_attr_t  attr;
+
+    if (c->threads <= 1) {
+        return NXT_UNIT_OK;
+    }
+
+    if (c->thread_stack_size > 0) {
+        res = pthread_attr_init(&attr);
+        if (nxt_slow_path(res != 0)) {
+            nxt_unit_alert(NULL, "thread attr init failed: %s (%d)",
+                           strerror(res), res);
+
+            return NXT_UNIT_ERROR;
+        }
+
+        res = pthread_attr_setstacksize(&attr, c->thread_stack_size);
+        if (nxt_slow_path(res != 0)) {
+            nxt_unit_alert(NULL, "thread attr set stack size failed: %s (%d)",
+                           strerror(res), res);
+
+            return NXT_UNIT_ERROR;
+        }
+
+        nxt_py_thread_attr = &attr;
+    }
+
+    nxt_py_threads = nxt_unit_malloc(NULL, sizeof(nxt_py_thread_info_t)
+                                           * (c->threads - 1));
+    if (nxt_slow_path(nxt_py_threads == NULL)) {
+        nxt_unit_alert(NULL, "Failed to allocate thread info array");
+
+        return NXT_UNIT_ERROR;
+    }
+
+    memset(nxt_py_threads, 0, sizeof(nxt_py_thread_info_t) * (c->threads - 1));
+
+    for (i = 0; i < c->threads - 1; i++) {
+        ti = &nxt_py_threads[i];
+
+        res = nxt_py_proto.ctx_data_alloc(&ti->ctx_data);
+        if (nxt_slow_path(res != NXT_UNIT_OK)) {
+            return NXT_UNIT_ERROR;
+        }
+    }
+
+    return NXT_UNIT_OK;
+}
+
+
+static int
+nxt_python_ready_handler(nxt_unit_ctx_t *ctx)
+{
+    int                    res;
+    uint32_t               i;
+    nxt_py_thread_info_t   *ti;
+    nxt_python_app_conf_t  *c;
+
+    if (nxt_py_proto.ready != NULL) {
+        res = nxt_py_proto.ready(ctx);
+        if (nxt_slow_path(res != NXT_UNIT_OK)) {
+            return NXT_UNIT_ERROR;
+        }
+    }
+
+    /* Worker thread context. */
+    if (!nxt_unit_is_main_ctx(ctx)) {
+        return NXT_UNIT_OK;
+    }
+
+    c = ctx->unit->data;
+
+    if (c->threads <= 1) {
+        return NXT_UNIT_OK;
+    }
+
+    for (i = 0; i < c->threads - 1; i++) {
+        ti = &nxt_py_threads[i];
+
+        ti->ctx = ctx;
+
+        res = pthread_create(&ti->thread, nxt_py_thread_attr,
+                             nxt_python_thread_func, ti);
+
+        if (nxt_fast_path(res == 0)) {
+            nxt_unit_debug(ctx, "thread #%d created", (int) (i + 1));
+
+        } else {
+            nxt_unit_alert(ctx, "thread #%d create failed: %s (%d)",
+                           (int) (i + 1), strerror(res), res);
+        }
+    }
+
+    return NXT_UNIT_OK;
+}
+
+
+static void *
+nxt_python_thread_func(void *data)
+{
+    nxt_unit_ctx_t        *ctx;
+    PyGILState_STATE      gstate;
+    nxt_py_thread_info_t  *ti;
+
+    ti = data;
+
+    nxt_unit_debug(ti->ctx, "worker thread #%d start",
+                   (int) (ti - nxt_py_threads + 1));
+
+    gstate = PyGILState_Ensure();
+
+    if (nxt_py_proto.startup != NULL) {
+        if (nxt_py_proto.startup(ti->ctx_data) != NXT_UNIT_OK) {
+            goto fail;
+        }
+    }
+
+    ctx = nxt_unit_ctx_alloc(ti->ctx, ti->ctx_data);
+    if (nxt_slow_path(ctx == NULL)) {
+        goto fail;
+    }
+
+    (void) nxt_py_proto.run(ctx);
+
+    nxt_unit_done(ctx);
+
+fail:
+
+    PyGILState_Release(gstate);
+
+    nxt_unit_debug(NULL, "worker thread #%d end",
+                   (int) (ti - nxt_py_threads + 1));
+
+    return NULL;
+}
+
+
+static void
+nxt_python_join_threads(nxt_unit_ctx_t *ctx, nxt_python_app_conf_t *c)
+{
+    int                   res;
+    uint32_t              i;
+    PyThreadState         *thread_state;
+    nxt_py_thread_info_t  *ti;
+
+    if (nxt_py_threads == NULL) {
+        return;
+    }
+
+    thread_state = PyEval_SaveThread();
+
+    for (i = 0; i < c->threads - 1; i++) {
+        ti = &nxt_py_threads[i];
+
+        if ((uintptr_t) ti->thread == 0) {
+            continue;
+        }
+
+        res = pthread_join(ti->thread, NULL);
+
+        if (nxt_fast_path(res == 0)) {
+            nxt_unit_debug(ctx, "thread #%d joined", (int) (i + 1));
+
+        } else {
+            nxt_unit_alert(ctx, "thread #%d join failed: %s (%d)",
+                           (int) (i + 1), strerror(res), res);
+        }
+    }
+
+    PyEval_RestoreThread(thread_state);
+
+    for (i = 0; i < c->threads - 1; i++) {
+        ti = &nxt_py_threads[i];
+
+        if (ti->ctx_data != NULL) {
+            nxt_py_proto.ctx_data_free(ti->ctx_data);
+        }
+    }
+
+    nxt_unit_free(NULL, nxt_py_threads);
+}
+
+
+int
 nxt_python_init_strings(nxt_python_string_t *pstr)
 {
     PyObject  *obj;
@@ -271,7 +504,7 @@ nxt_python_init_strings(nxt_python_string_t *pstr)
         obj = PyString_FromStringAndSize((char *) pstr->string.start,
                                          pstr->string.length);
         if (nxt_slow_path(obj == NULL)) {
-            return NXT_ERROR;
+            return NXT_UNIT_ERROR;
         }
 
         PyUnicode_InternInPlace(&obj);
@@ -281,7 +514,7 @@ nxt_python_init_strings(nxt_python_string_t *pstr)
         pstr++;
     }
 
-    return NXT_OK;
+    return NXT_UNIT_OK;
 }
 
 
@@ -304,8 +537,9 @@ nxt_python_done_strings(nxt_python_string_t *pstr)
 static void
 nxt_python_atexit(void)
 {
-    nxt_python_wsgi_done();
-    nxt_python_asgi_done();
+    if (nxt_py_proto.done != NULL) {
+        nxt_py_proto.done();
+    }
 
     Py_XDECREF(nxt_py_stderr_flush);
     Py_XDECREF(nxt_py_application);
diff --git a/src/python/nxt_python.h b/src/python/nxt_python.h
index 6d7eba8e..b581dd46 100644
--- a/src/python/nxt_python.h
+++ b/src/python/nxt_python.h
@@ -44,20 +44,25 @@ typedef struct {
     PyObject   **object_p;
 } nxt_python_string_t;
 
+typedef struct {
+    int   (*ctx_data_alloc)(void **pdata);
+    void  (*ctx_data_free)(void *data);
+    int   (*startup)(void *data);
+    int   (*run)(nxt_unit_ctx_t *ctx);
+    int   (*ready)(nxt_unit_ctx_t *ctx);
+    void  (*done)(void);
+} nxt_python_proto_t;
+
 
-nxt_int_t nxt_python_init_strings(nxt_python_string_t *pstr);
+int nxt_python_init_strings(nxt_python_string_t *pstr);
 void nxt_python_done_strings(nxt_python_string_t *pstr);
 
 void nxt_python_print_exception(void);
 
-nxt_int_t nxt_python_wsgi_init(nxt_task_t *task, nxt_unit_init_t *init);
-int nxt_python_wsgi_run(nxt_unit_ctx_t *ctx);
-void nxt_python_wsgi_done(void);
+int nxt_python_wsgi_init(nxt_unit_init_t *init, nxt_python_proto_t *proto);
 
 int nxt_python_asgi_check(PyObject *obj);
-nxt_int_t nxt_python_asgi_init(nxt_task_t *task, nxt_unit_init_t *init);
-nxt_int_t nxt_python_asgi_run(nxt_unit_ctx_t *ctx);
-void nxt_python_asgi_done(void);
+int nxt_python_asgi_init(nxt_unit_init_t *init, nxt_python_proto_t *proto);
 
 
 #endif  /* _NXT_PYTHON_H_INCLUDED_ */
diff --git a/src/python/nxt_python_asgi.c b/src/python/nxt_python_asgi.c
index 72408ea1..a188ff56 100644
--- a/src/python/nxt_python_asgi.c
+++ b/src/python/nxt_python_asgi.c
@@ -16,6 +16,13 @@
 #include <python/nxt_python_asgi_str.h>
 
 
+static int nxt_python_asgi_ctx_data_alloc(void **pdata);
+static void nxt_python_asgi_ctx_data_free(void *data);
+static int nxt_python_asgi_startup(void *data);
+static int nxt_python_asgi_run(nxt_unit_ctx_t *ctx);
+
+static void nxt_py_asgi_remove_reader(nxt_unit_ctx_t *ctx,
+    nxt_unit_port_t *port);
 static void nxt_py_asgi_request_handler(nxt_unit_request_info_t *req);
 
 static PyObject *nxt_py_asgi_create_http_scope(nxt_unit_request_info_t *req);
@@ -24,30 +31,32 @@ static PyObject *nxt_py_asgi_create_address(nxt_unit_sptr_t *sptr, uint8_t len,
 static PyObject *nxt_py_asgi_create_header(nxt_unit_field_t *f);
 static PyObject *nxt_py_asgi_create_subprotocols(nxt_unit_field_t *f);
 
+static int nxt_python_asgi_ready(nxt_unit_ctx_t *ctx);
+
 static int nxt_py_asgi_add_port(nxt_unit_ctx_t *ctx, nxt_unit_port_t *port);
 static void nxt_py_asgi_remove_port(nxt_unit_t *lib, nxt_unit_port_t *port);
 static void nxt_py_asgi_quit(nxt_unit_ctx_t *ctx);
 static void nxt_py_asgi_shm_ack_handler(nxt_unit_ctx_t *ctx);
 
 static PyObject *nxt_py_asgi_port_read(PyObject *self, PyObject *args);
+static void nxt_python_asgi_done(void);
 
 
-PyObject  *nxt_py_loop_run_until_complete;
-PyObject  *nxt_py_loop_create_future;
-PyObject  *nxt_py_loop_create_task;
-
-nxt_queue_t  nxt_py_asgi_drain_queue;
-
-static PyObject  *nxt_py_loop_call_soon;
-static PyObject  *nxt_py_quit_future;
-static PyObject  *nxt_py_quit_future_set_result;
-static PyObject  *nxt_py_loop_add_reader;
-static PyObject  *nxt_py_loop_remove_reader;
-static PyObject  *nxt_py_port_read;
+static PyObject           *nxt_py_port_read;
+static nxt_unit_port_t    *nxt_py_shared_port;
 
 static PyMethodDef        nxt_py_port_read_method =
     {"unit_port_read", nxt_py_asgi_port_read, METH_VARARGS, ""};
 
+static nxt_python_proto_t  nxt_py_asgi_proto = {
+    .ctx_data_alloc = nxt_python_asgi_ctx_data_alloc,
+    .ctx_data_free  = nxt_python_asgi_ctx_data_free,
+    .startup        = nxt_python_asgi_startup,
+    .run            = nxt_python_asgi_run,
+    .ready          = nxt_python_asgi_ready,
+    .done           = nxt_python_asgi_done,
+};
+
 #define NXT_UNIT_HASH_WS_PROTOCOL  0xED0A
 
 
@@ -102,202 +111,254 @@ nxt_python_asgi_check(PyObject *obj)
 }
 
 
-nxt_int_t
-nxt_python_asgi_init(nxt_task_t *task, nxt_unit_init_t *init)
+int
+nxt_python_asgi_init(nxt_unit_init_t *init, nxt_python_proto_t *proto)
 {
-    PyObject   *asyncio, *loop, *get_event_loop;
-    nxt_int_t  rc;
-
-    nxt_debug(task, "asgi_init");
+    nxt_unit_debug(NULL, "asgi_init");
 
-    if (nxt_slow_path(nxt_py_asgi_str_init() != NXT_OK)) {
-        nxt_alert(task, "Python failed to init string objects");
-        return NXT_ERROR;
+    if (nxt_slow_path(nxt_py_asgi_str_init() != NXT_UNIT_OK)) {
+        nxt_unit_alert(NULL, "Python failed to init string objects");
+        return NXT_UNIT_ERROR;
     }
 
-    asyncio = PyImport_ImportModule("asyncio");
-    if (nxt_slow_path(asyncio == NULL)) {
-        nxt_alert(task, "Python failed to import module 'asyncio'");
-        nxt_python_print_exception();
-        return NXT_ERROR;
+    nxt_py_port_read = PyCFunction_New(&nxt_py_port_read_method, NULL);
+    if (nxt_slow_path(nxt_py_port_read == NULL)) {
+        nxt_unit_alert(NULL,
+                       "Python failed to initialize the 'port_read' function");
+        return NXT_UNIT_ERROR;
     }
 
-    loop = NULL;
-    get_event_loop = PyDict_GetItemString(PyModule_GetDict(asyncio),
-                                          "get_event_loop");
-    if (nxt_slow_path(get_event_loop == NULL)) {
-        nxt_alert(task,
-                 "Python failed to get 'get_event_loop' from module 'asyncio'");
-        goto fail;
+    if (nxt_slow_path(nxt_py_asgi_http_init() == NXT_UNIT_ERROR)) {
+        return NXT_UNIT_ERROR;
     }
 
-    if (nxt_slow_path(PyCallable_Check(get_event_loop) == 0)) {
-        nxt_alert(task, "'asyncio.get_event_loop' is not a callable object");
-        goto fail;
+    if (nxt_slow_path(nxt_py_asgi_websocket_init() == NXT_UNIT_ERROR)) {
+        return NXT_UNIT_ERROR;
     }
 
-    loop = PyObject_CallObject(get_event_loop, NULL);
-    if (nxt_slow_path(loop == NULL)) {
-        nxt_alert(task, "Python failed to call 'asyncio.get_event_loop'");
-        goto fail;
-    }
+    init->callbacks.request_handler = nxt_py_asgi_request_handler;
+    init->callbacks.data_handler = nxt_py_asgi_http_data_handler;
+    init->callbacks.websocket_handler = nxt_py_asgi_websocket_handler;
+    init->callbacks.close_handler = nxt_py_asgi_websocket_close_handler;
+    init->callbacks.quit = nxt_py_asgi_quit;
+    init->callbacks.shm_ack_handler = nxt_py_asgi_shm_ack_handler;
+    init->callbacks.add_port = nxt_py_asgi_add_port;
+    init->callbacks.remove_port = nxt_py_asgi_remove_port;
 
-    nxt_py_loop_create_task = PyObject_GetAttrString(loop, "create_task");
-    if (nxt_slow_path(nxt_py_loop_create_task == NULL)) {
-        nxt_alert(task, "Python failed to get 'loop.create_task'");
-        goto fail;
-    }
+    *proto = nxt_py_asgi_proto;
 
-    if (nxt_slow_path(PyCallable_Check(nxt_py_loop_create_task) == 0)) {
-        nxt_alert(task, "'loop.create_task' is not a callable object");
-        goto fail;
-    }
+    return NXT_UNIT_OK;
+}
 
-    nxt_py_loop_add_reader = PyObject_GetAttrString(loop, "add_reader");
-    if (nxt_slow_path(nxt_py_loop_add_reader == NULL)) {
-        nxt_alert(task, "Python failed to get 'loop.add_reader'");
-        goto fail;
-    }
 
-    if (nxt_slow_path(PyCallable_Check(nxt_py_loop_add_reader) == 0)) {
-        nxt_alert(task, "'loop.add_reader' is not a callable object");
-        goto fail;
-    }
+static int
+nxt_python_asgi_ctx_data_alloc(void **pdata)
+{
+    uint32_t                i;
+    PyObject                *asyncio, *loop, *new_event_loop, *obj;
+    nxt_py_asgi_ctx_data_t  *ctx_data;
 
-    nxt_py_loop_remove_reader = PyObject_GetAttrString(loop, "remove_reader");
-    if (nxt_slow_path(nxt_py_loop_remove_reader == NULL)) {
-        nxt_alert(task, "Python failed to get 'loop.remove_reader'");
-        goto fail;
+    ctx_data = nxt_unit_malloc(NULL, sizeof(nxt_py_asgi_ctx_data_t));
+    if (nxt_slow_path(ctx_data == NULL)) {
+        nxt_unit_alert(NULL, "Failed to allocate context data");
+        return NXT_UNIT_ERROR;
     }
 
-    if (nxt_slow_path(PyCallable_Check(nxt_py_loop_remove_reader) == 0)) {
-        nxt_alert(task, "'loop.remove_reader' is not a callable object");
-        goto fail;
-    }
+    memset(ctx_data, 0, sizeof(nxt_py_asgi_ctx_data_t));
 
-    nxt_py_loop_call_soon = PyObject_GetAttrString(loop, "call_soon");
-    if (nxt_slow_path(nxt_py_loop_call_soon == NULL)) {
-        nxt_alert(task, "Python failed to get 'loop.call_soon'");
-        goto fail;
-    }
+    nxt_queue_init(&ctx_data->drain_queue);
 
-    if (nxt_slow_path(PyCallable_Check(nxt_py_loop_call_soon) == 0)) {
-        nxt_alert(task, "'loop.call_soon' is not a callable object");
-        goto fail;
-    }
+    struct {
+        const char  *key;
+        PyObject    **handler;
 
-    nxt_py_loop_run_until_complete = PyObject_GetAttrString(loop,
-                                                          "run_until_complete");
-    if (nxt_slow_path(nxt_py_loop_run_until_complete == NULL)) {
-        nxt_alert(task, "Python failed to get 'loop.run_until_complete'");
-        goto fail;
-    }
+    } handlers[] = {
+        { "create_task",        &ctx_data->loop_create_task },
+        { "add_reader",         &ctx_data->loop_add_reader },
+        { "remove_reader",      &ctx_data->loop_remove_reader },
+        { "call_soon",          &ctx_data->loop_call_soon },
+        { "run_until_complete", &ctx_data->loop_run_until_complete },
+        { "create_future",      &ctx_data->loop_create_future },
+    };
 
-    if (nxt_slow_path(PyCallable_Check(nxt_py_loop_run_until_complete) == 0)) {
-        nxt_alert(task, "'loop.run_until_complete' is not a callable object");
-        goto fail;
-    }
+    loop = NULL;
 
-    nxt_py_loop_create_future = PyObject_GetAttrString(loop, "create_future");
-    if (nxt_slow_path(nxt_py_loop_create_future == NULL)) {
-        nxt_alert(task, "Python failed to get 'loop.create_future'");
+    asyncio = PyImport_ImportModule("asyncio");
+    if (nxt_slow_path(asyncio == NULL)) {
+        nxt_unit_alert(NULL, "Python failed to import module 'asyncio'");
+        nxt_python_print_exception();
         goto fail;
     }
 
-    if (nxt_slow_path(PyCallable_Check(nxt_py_loop_create_future) == 0)) {
-        nxt_alert(task, "'loop.create_future' is not a callable object");
+    new_event_loop = PyDict_GetItemString(PyModule_GetDict(asyncio),
+                                          "new_event_loop");
+    if (nxt_slow_path(new_event_loop == NULL)) {
+        nxt_unit_alert(NULL,
+                 "Python failed to get 'new_event_loop' from module 'asyncio'");
         goto fail;
     }
 
-    nxt_py_quit_future = PyObject_CallObject(nxt_py_loop_create_future, NULL);
-    if (nxt_slow_path(nxt_py_quit_future == NULL)) {
-        nxt_alert(task, "Python failed to create Future ");
-        nxt_python_print_exception();
+    if (nxt_slow_path(PyCallable_Check(new_event_loop) == 0)) {
+        nxt_unit_alert(NULL,
+                       "'asyncio.new_event_loop' is not a callable object");
         goto fail;
     }
 
-    nxt_py_quit_future_set_result = PyObject_GetAttrString(nxt_py_quit_future,
-                                                           "set_result");
-    if (nxt_slow_path(nxt_py_quit_future_set_result == NULL)) {
-        nxt_alert(task, "Python failed to get 'future.set_result'");
+    loop = PyObject_CallObject(new_event_loop, NULL);
+    if (nxt_slow_path(loop == NULL)) {
+        nxt_unit_alert(NULL, "Python failed to call 'asyncio.new_event_loop'");
         goto fail;
     }
 
-    if (nxt_slow_path(PyCallable_Check(nxt_py_quit_future_set_result) == 0)) {
-        nxt_alert(task, "'future.set_result' is not a callable object");
-        goto fail;
+    for (i = 0; i < nxt_nitems(handlers); i++) {
+        obj = PyObject_GetAttrString(loop, handlers[i].key);
+        if (nxt_slow_path(obj == NULL)) {
+            nxt_unit_alert(NULL, "Python failed to get 'loop.%s'",
+                                 handlers[i].key);
+            goto fail;
+        }
+
+        *handlers[i].handler = obj;
+
+        if (nxt_slow_path(PyCallable_Check(obj) == 0)) {
+            nxt_unit_alert(NULL, "'loop.%s' is not a callable object",
+                                 handlers[i].key);
+            goto fail;
+        }
     }
 
-    nxt_py_port_read = PyCFunction_New(&nxt_py_port_read_method, NULL);
-    if (nxt_slow_path(nxt_py_port_read == NULL)) {
-        nxt_alert(task, "Python failed to initialize the 'port_read' function");
+    obj = PyObject_CallObject(ctx_data->loop_create_future, NULL);
+    if (nxt_slow_path(obj == NULL)) {
+        nxt_unit_alert(NULL, "Python failed to create Future ");
+        nxt_python_print_exception();
         goto fail;
     }
 
-    nxt_queue_init(&nxt_py_asgi_drain_queue);
+    ctx_data->quit_future = obj;
 
-    if (nxt_slow_path(nxt_py_asgi_http_init(task) == NXT_ERROR)) {
+    obj = PyObject_GetAttrString(ctx_data->quit_future, "set_result");
+    if (nxt_slow_path(obj == NULL)) {
+        nxt_unit_alert(NULL, "Python failed to get 'future.set_result'");
         goto fail;
     }
 
-    if (nxt_slow_path(nxt_py_asgi_websocket_init(task) == NXT_ERROR)) {
-        goto fail;
-    }
+    ctx_data->quit_future_set_result = obj;
 
-    rc = nxt_py_asgi_lifespan_startup(task);
-    if (nxt_slow_path(rc == NXT_ERROR)) {
+    if (nxt_slow_path(PyCallable_Check(obj) == 0)) {
+        nxt_unit_alert(NULL, "'future.set_result' is not a callable object");
         goto fail;
     }
 
-    init->callbacks.request_handler = nxt_py_asgi_request_handler;
-    init->callbacks.data_handler = nxt_py_asgi_http_data_handler;
-    init->callbacks.websocket_handler = nxt_py_asgi_websocket_handler;
-    init->callbacks.close_handler = nxt_py_asgi_websocket_close_handler;
-    init->callbacks.quit = nxt_py_asgi_quit;
-    init->callbacks.shm_ack_handler = nxt_py_asgi_shm_ack_handler;
-    init->callbacks.add_port = nxt_py_asgi_add_port;
-    init->callbacks.remove_port = nxt_py_asgi_remove_port;
-
     Py_DECREF(loop);
     Py_DECREF(asyncio);
 
-    return NXT_OK;
+    *pdata = ctx_data;
+
+    return NXT_UNIT_OK;
 
 fail:
 
+    nxt_python_asgi_ctx_data_free(ctx_data);
+
     Py_XDECREF(loop);
-    Py_DECREF(asyncio);
+    Py_XDECREF(asyncio);
+
+    return NXT_UNIT_ERROR;
+}
+
 
-    return NXT_ERROR;
+static void
+nxt_python_asgi_ctx_data_free(void *data)
+{
+    nxt_py_asgi_ctx_data_t  *ctx_data;
+
+    ctx_data = data;
+
+    Py_XDECREF(ctx_data->loop_run_until_complete);
+    Py_XDECREF(ctx_data->loop_create_future);
+    Py_XDECREF(ctx_data->loop_create_task);
+    Py_XDECREF(ctx_data->loop_call_soon);
+    Py_XDECREF(ctx_data->loop_add_reader);
+    Py_XDECREF(ctx_data->loop_remove_reader);
+    Py_XDECREF(ctx_data->quit_future);
+    Py_XDECREF(ctx_data->quit_future_set_result);
+
+    nxt_unit_free(NULL, ctx_data);
 }
 
 
-nxt_int_t
+static int
+nxt_python_asgi_startup(void *data)
+{
+    return nxt_py_asgi_lifespan_startup(data);
+}
+
+
+static int
 nxt_python_asgi_run(nxt_unit_ctx_t *ctx)
 {
-    PyObject  *res;
+    PyObject                *res;
+    nxt_py_asgi_ctx_data_t  *ctx_data;
+
+    ctx_data = ctx->data;
 
-    res = PyObject_CallFunctionObjArgs(nxt_py_loop_run_until_complete,
-                                       nxt_py_quit_future, NULL);
+    res = PyObject_CallFunctionObjArgs(ctx_data->loop_run_until_complete,
+                                       ctx_data->quit_future, NULL);
     if (nxt_slow_path(res == NULL)) {
         nxt_unit_alert(ctx, "Python failed to call loop.run_until_complete");
         nxt_python_print_exception();
 
-        return NXT_ERROR;
+        return NXT_UNIT_ERROR;
     }
 
     Py_DECREF(res);
 
-    nxt_py_asgi_lifespan_shutdown();
+    nxt_py_asgi_remove_reader(ctx, nxt_py_shared_port);
+    nxt_py_asgi_remove_reader(ctx, ctx_data->port);
 
-    return NXT_OK;
+    if (ctx_data->port != NULL) {
+        ctx_data->port->data = NULL;
+        ctx_data->port = NULL;
+    }
+
+    nxt_py_asgi_lifespan_shutdown(ctx);
+
+    return NXT_UNIT_OK;
+}
+
+
+static void
+nxt_py_asgi_remove_reader(nxt_unit_ctx_t *ctx, nxt_unit_port_t *port)
+{
+    PyObject                *res;
+    nxt_py_asgi_ctx_data_t  *ctx_data;
+
+    if (port == NULL || port->in_fd == -1) {
+        return;
+    }
+
+    ctx_data = ctx->data;
+
+    nxt_unit_debug(ctx, "asgi_remove_reader %d %p", port->in_fd, port);
+
+    res = PyObject_CallFunctionObjArgs(ctx_data->loop_remove_reader,
+                                       PyLong_FromLong(port->in_fd), NULL);
+    if (nxt_slow_path(res == NULL)) {
+        nxt_unit_alert(ctx, "Python failed to remove_reader");
+        nxt_python_print_exception();
+
+        return;
+    }
+
+    Py_DECREF(res);
 }
 
 
 static void
 nxt_py_asgi_request_handler(nxt_unit_request_info_t *req)
 {
-    PyObject  *scope, *res, *task, *receive, *send, *done, *asgi;
+    PyObject                *scope, *res, *task, *receive, *send, *done, *asgi;
+    nxt_py_asgi_ctx_data_t  *ctx_data;
 
     if (req->request->websocket_handshake) {
         asgi = nxt_py_asgi_websocket_create(req);
@@ -365,7 +426,9 @@ nxt_py_asgi_request_handler(nxt_unit_request_info_t *req)
         goto release_scope;
     }
 
-    task = PyObject_CallFunctionObjArgs(nxt_py_loop_create_task, res, NULL);
+    ctx_data = req->ctx->data;
+
+    task = PyObject_CallFunctionObjArgs(ctx_data->loop_create_task, res, NULL);
     if (nxt_slow_path(task == NULL)) {
         nxt_unit_req_error(req, "Python failed to call the create_task");
         nxt_python_print_exception();
@@ -724,10 +787,46 @@ fail:
 
 
 static int
+nxt_python_asgi_ready(nxt_unit_ctx_t *ctx)
+{
+    PyObject                *res;
+    nxt_unit_port_t         *port;
+    nxt_py_asgi_ctx_data_t  *ctx_data;
+
+    if (nxt_slow_path(nxt_py_shared_port == NULL)) {
+        return NXT_UNIT_ERROR;
+    }
+
+    port = nxt_py_shared_port;
+
+    nxt_unit_debug(ctx, "asgi_ready %d %p %p", port->in_fd, ctx, port);
+
+    ctx_data = ctx->data;
+
+    res = PyObject_CallFunctionObjArgs(ctx_data->loop_add_reader,
+                                       PyLong_FromLong(port->in_fd),
+                                       nxt_py_port_read,
+                                       PyLong_FromVoidPtr(ctx),
+                                       PyLong_FromVoidPtr(port), NULL);
+    if (nxt_slow_path(res == NULL)) {
+        nxt_unit_alert(ctx, "Python failed to add_reader");
+        nxt_python_print_exception();
+
+        return NXT_UNIT_ERROR;
+    }
+
+    Py_DECREF(res);
+
+    return NXT_UNIT_OK;
+}
+
+
+static int
 nxt_py_asgi_add_port(nxt_unit_ctx_t *ctx, nxt_unit_port_t *port)
 {
-    int       nb;
-    PyObject  *res;
+    int                     nb;
+    PyObject                *res;
+    nxt_py_asgi_ctx_data_t  *ctx_data;
 
     if (port->in_fd == -1) {
         return NXT_UNIT_OK;
@@ -744,13 +843,25 @@ nxt_py_asgi_add_port(nxt_unit_ctx_t *ctx, nxt_unit_port_t *port)
 
     nxt_unit_debug(ctx, "asgi_add_port %d %p %p", port->in_fd, ctx, port);
 
-    res = PyObject_CallFunctionObjArgs(nxt_py_loop_add_reader,
+    if (port->id.id == NXT_UNIT_SHARED_PORT_ID) {
+        nxt_py_shared_port = port;
+
+        return NXT_UNIT_OK;
+    }
+
+    ctx_data = ctx->data;
+
+    ctx_data->port = port;
+    port->data = ctx_data;
+
+    res = PyObject_CallFunctionObjArgs(ctx_data->loop_add_reader,
                                        PyLong_FromLong(port->in_fd),
                                        nxt_py_port_read,
                                        PyLong_FromVoidPtr(ctx),
                                        PyLong_FromVoidPtr(port), NULL);
     if (nxt_slow_path(res == NULL)) {
         nxt_unit_alert(ctx, "Python failed to add_reader");
+        nxt_python_print_exception();
 
         return NXT_UNIT_ERROR;
     }
@@ -764,53 +875,67 @@ nxt_py_asgi_add_port(nxt_unit_ctx_t *ctx, nxt_unit_port_t *port)
 static void
 nxt_py_asgi_remove_port(nxt_unit_t *lib, nxt_unit_port_t *port)
 {
-    PyObject  *res;
-
-    nxt_unit_debug(NULL, "asgi_remove_port %d %p", port->in_fd, port);
-
     if (port->in_fd == -1) {
         return;
     }
 
-    res = PyObject_CallFunctionObjArgs(nxt_py_loop_remove_reader,
-                                       PyLong_FromLong(port->in_fd), NULL);
-    if (nxt_slow_path(res == NULL)) {
-        nxt_unit_alert(NULL, "Python failed to remove_reader");
-    }
+    nxt_unit_debug(NULL, "asgi_remove_port %d %p", port->in_fd, port);
 
-    Py_DECREF(res);
+    if (nxt_py_shared_port == port) {
+        nxt_py_shared_port = NULL;
+    }
 }
 
 
 static void
 nxt_py_asgi_quit(nxt_unit_ctx_t *ctx)
 {
-    PyObject  *res;
+    PyObject                *res;
+    nxt_py_asgi_ctx_data_t  *ctx_data;
 
     nxt_unit_debug(ctx, "asgi_quit %p", ctx);
 
-    res = PyObject_CallFunctionObjArgs(nxt_py_quit_future_set_result,
+    ctx_data = ctx->data;
+
+    if (nxt_py_shared_port != NULL) {
+        res = PyObject_CallFunctionObjArgs(ctx_data->loop_remove_reader,
+                              PyLong_FromLong(nxt_py_shared_port->in_fd), NULL);
+        if (nxt_slow_path(res == NULL)) {
+            nxt_unit_alert(NULL, "Python failed to remove_reader");
+            nxt_python_print_exception();
+
+        } else {
+            Py_DECREF(res);
+        }
+    }
+
+    res = PyObject_CallFunctionObjArgs(ctx_data->quit_future_set_result,
                                        PyLong_FromLong(0), NULL);
     if (nxt_slow_path(res == NULL)) {
         nxt_unit_alert(ctx, "Python failed to set_result");
-    }
+        nxt_python_print_exception();
 
-    Py_DECREF(res);
+    } else {
+        Py_DECREF(res);
+    }
 }
 
 
 static void
 nxt_py_asgi_shm_ack_handler(nxt_unit_ctx_t *ctx)
 {
-    int               rc;
-    nxt_queue_link_t  *lnk;
+    int                     rc;
+    nxt_queue_link_t        *lnk;
+    nxt_py_asgi_ctx_data_t  *ctx_data;
+
+    ctx_data = ctx->data;
 
-    while (!nxt_queue_is_empty(&nxt_py_asgi_drain_queue)) {
-        lnk = nxt_queue_first(&nxt_py_asgi_drain_queue);
+    while (!nxt_queue_is_empty(&ctx_data->drain_queue)) {
+        lnk = nxt_queue_first(&ctx_data->drain_queue);
 
         rc = nxt_py_asgi_http_drain(lnk);
         if (rc == NXT_UNIT_AGAIN) {
-            break;
+            return;
         }
 
         nxt_queue_remove(lnk);
@@ -859,7 +984,7 @@ nxt_py_asgi_port_read(PyObject *self, PyObject *args)
 
     if (nxt_slow_path(rc == NXT_UNIT_ERROR)) {
         return PyErr_Format(PyExc_RuntimeError,
-                            "error processing port message");
+                            "error processing port %d message", port->id.id);
     }
 
     Py_RETURN_NONE;
@@ -996,8 +1121,8 @@ nxt_py_asgi_add_field(void *data, int i, PyObject *name, PyObject *val)
 
 
 PyObject *
-nxt_py_asgi_set_result_soon(nxt_unit_request_info_t *req, PyObject *future,
-    PyObject *result)
+nxt_py_asgi_set_result_soon(nxt_unit_request_info_t *req,
+    nxt_py_asgi_ctx_data_t *ctx_data, PyObject *future, PyObject *result)
 {
     PyObject  *set_result, *res;
 
@@ -1013,7 +1138,7 @@ nxt_py_asgi_set_result_soon(nxt_unit_request_info_t *req, PyObject *future,
 
         Py_CLEAR(future);
 
-        goto cleanup;
+        goto cleanup_result;
     }
 
     if (nxt_slow_path(PyCallable_Check(set_result) == 0)) {
@@ -1024,7 +1149,7 @@ nxt_py_asgi_set_result_soon(nxt_unit_request_info_t *req, PyObject *future,
         goto cleanup;
     }
 
-    res = PyObject_CallFunctionObjArgs(nxt_py_loop_call_soon, set_result,
+    res = PyObject_CallFunctionObjArgs(ctx_data->loop_call_soon, set_result,
                                        result, NULL);
     if (nxt_slow_path(res == NULL)) {
         nxt_unit_req_alert(req, "Python failed to call 'loop.call_soon'");
@@ -1038,6 +1163,9 @@ nxt_py_asgi_set_result_soon(nxt_unit_request_info_t *req, PyObject *future,
 cleanup:
 
     Py_DECREF(set_result);
+
+cleanup_result:
+
     Py_DECREF(result);
 
     return future;
@@ -1148,6 +1276,17 @@ nxt_py_asgi_new_scope(nxt_unit_request_info_t *req, PyObject *type,
 
 
 void
+nxt_py_asgi_drain_wait(nxt_unit_request_info_t *req, nxt_queue_link_t *link)
+{
+    nxt_py_asgi_ctx_data_t  *ctx_data;
+
+    ctx_data = req->ctx->data;
+
+    nxt_queue_insert_tail(&ctx_data->drain_queue, link);
+}
+
+
+void
 nxt_py_asgi_dealloc(PyObject *self)
 {
     PyObject_Del(self);
@@ -1177,19 +1316,11 @@ nxt_py_asgi_next(PyObject *self)
 }
 
 
-void
+static void
 nxt_python_asgi_done(void)
 {
     nxt_py_asgi_str_done();
 
-    Py_XDECREF(nxt_py_quit_future);
-    Py_XDECREF(nxt_py_quit_future_set_result);
-    Py_XDECREF(nxt_py_loop_run_until_complete);
-    Py_XDECREF(nxt_py_loop_create_future);
-    Py_XDECREF(nxt_py_loop_create_task);
-    Py_XDECREF(nxt_py_loop_call_soon);
-    Py_XDECREF(nxt_py_loop_add_reader);
-    Py_XDECREF(nxt_py_loop_remove_reader);
     Py_XDECREF(nxt_py_port_read);
 }
 
@@ -1203,25 +1334,12 @@ nxt_python_asgi_check(PyObject *obj)
 }
 
 
-nxt_int_t
-nxt_python_asgi_init(nxt_task_t *task, nxt_unit_init_t *init)
-{
-    nxt_alert(task, "ASGI not implemented");
-    return NXT_ERROR;
-}
-
-
-nxt_int_t
-nxt_python_asgi_run(nxt_unit_ctx_t *ctx)
+int
+nxt_python_asgi_init(nxt_unit_init_t *init, nxt_python_proto_t *proto)
 {
-    nxt_unit_alert(ctx, "ASGI not implemented");
-    return NXT_ERROR;
+    nxt_unit_alert(NULL, "ASGI not implemented");
+    return NXT_UNIT_ERROR;
 }
 
 
-void
-nxt_python_asgi_done(void)
-{
-}
-
 #endif /* NXT_HAVE_ASGI */
diff --git a/src/python/nxt_python_asgi.h b/src/python/nxt_python_asgi.h
index 24337c37..69d58477 100644
--- a/src/python/nxt_python_asgi.h
+++ b/src/python/nxt_python_asgi.h
@@ -10,6 +10,9 @@
 typedef PyObject * (*nxt_py_asgi_enum_header_cb)(void *ctx, int i,
     PyObject *name, PyObject *val);
 
+void nxt_py_asgi_drain_wait(nxt_unit_request_info_t *req,
+    nxt_queue_link_t *link);
+
 typedef struct {
     uint32_t       fields_count;
     uint32_t       fields_size;
@@ -20,6 +23,20 @@ typedef struct {
     uint64_t                 content_length;
 } nxt_py_asgi_add_field_ctx_t;
 
+typedef struct {
+    nxt_queue_t      drain_queue;
+    PyObject         *loop_run_until_complete;
+    PyObject         *loop_create_future;
+    PyObject         *loop_create_task;
+    PyObject         *loop_call_soon;
+    PyObject         *loop_add_reader;
+    PyObject         *loop_remove_reader;
+    PyObject         *quit_future;
+    PyObject         *quit_future_set_result;
+    PyObject         *lifespan;
+    nxt_unit_port_t  *port;
+} nxt_py_asgi_ctx_data_t;
+
 PyObject *nxt_py_asgi_enum_headers(PyObject *headers,
     nxt_py_asgi_enum_header_cb cb, void *data);
 
@@ -27,7 +44,7 @@ PyObject *nxt_py_asgi_calc_size(void *data, int i, PyObject *n, PyObject *v);
 PyObject *nxt_py_asgi_add_field(void *data, int i, PyObject *n, PyObject *v);
 
 PyObject *nxt_py_asgi_set_result_soon(nxt_unit_request_info_t *req,
-    PyObject *future, PyObject *result);
+    nxt_py_asgi_ctx_data_t *ctx_data, PyObject *future, PyObject *result);
 PyObject *nxt_py_asgi_new_msg(nxt_unit_request_info_t *req, PyObject *type);
 PyObject *nxt_py_asgi_new_scope(nxt_unit_request_info_t *req, PyObject *type,
     PyObject *spec_version);
@@ -37,24 +54,18 @@ PyObject *nxt_py_asgi_await(PyObject *self);
 PyObject *nxt_py_asgi_iter(PyObject *self);
 PyObject *nxt_py_asgi_next(PyObject *self);
 
-nxt_int_t nxt_py_asgi_http_init(nxt_task_t *task);
+int nxt_py_asgi_http_init(void);
 PyObject *nxt_py_asgi_http_create(nxt_unit_request_info_t *req);
 void nxt_py_asgi_http_data_handler(nxt_unit_request_info_t *req);
 int nxt_py_asgi_http_drain(nxt_queue_link_t *lnk);
 
-nxt_int_t nxt_py_asgi_websocket_init(nxt_task_t *task);
+int nxt_py_asgi_websocket_init(void);
 PyObject *nxt_py_asgi_websocket_create(nxt_unit_request_info_t *req);
 void nxt_py_asgi_websocket_handler(nxt_unit_websocket_frame_t *ws);
 void nxt_py_asgi_websocket_close_handler(nxt_unit_request_info_t *req);
 
-nxt_int_t nxt_py_asgi_lifespan_startup(nxt_task_t *task);
-nxt_int_t nxt_py_asgi_lifespan_shutdown(void);
-
-extern PyObject  *nxt_py_loop_run_until_complete;
-extern PyObject  *nxt_py_loop_create_future;
-extern PyObject  *nxt_py_loop_create_task;
-
-extern nxt_queue_t  nxt_py_asgi_drain_queue;
+int nxt_py_asgi_lifespan_startup(nxt_py_asgi_ctx_data_t *ctx_data);
+int nxt_py_asgi_lifespan_shutdown(nxt_unit_ctx_t *ctx);
 
 
 #endif  /* _NXT_PYTHON_ASGI_H_INCLUDED_ */
diff --git a/src/python/nxt_python_asgi_http.c b/src/python/nxt_python_asgi_http.c
index b07d61d6..a5034ea6 100644
--- a/src/python/nxt_python_asgi_http.c
+++ b/src/python/nxt_python_asgi_http.c
@@ -67,15 +67,16 @@ static PyTypeObject nxt_py_asgi_http_type = {
 static Py_ssize_t  nxt_py_asgi_http_body_buf_size = 32 * 1024 * 1024;
 
 
-nxt_int_t
-nxt_py_asgi_http_init(nxt_task_t *task)
+int
+nxt_py_asgi_http_init(void)
 {
     if (nxt_slow_path(PyType_Ready(&nxt_py_asgi_http_type) != 0)) {
-        nxt_alert(task, "Python failed to initialize the 'http' type object");
-        return NXT_ERROR;
+        nxt_unit_alert(NULL,
+                       "Python failed to initialize the 'http' type object");
+        return NXT_UNIT_ERROR;
     }
 
-    return NXT_OK;
+    return NXT_UNIT_OK;
 }
 
 
@@ -106,6 +107,7 @@ nxt_py_asgi_http_receive(PyObject *self, PyObject *none)
 {
     PyObject                 *msg, *future;
     nxt_py_asgi_http_t       *http;
+    nxt_py_asgi_ctx_data_t   *ctx_data;
     nxt_unit_request_info_t  *req;
 
     http = (nxt_py_asgi_http_t *) self;
@@ -118,7 +120,9 @@ nxt_py_asgi_http_receive(PyObject *self, PyObject *none)
         return NULL;
     }
 
-    future = PyObject_CallObject(nxt_py_loop_create_future, NULL);
+    ctx_data = req->ctx->data;
+
+    future = PyObject_CallObject(ctx_data->loop_create_future, NULL);
     if (nxt_slow_path(future == NULL)) {
         nxt_unit_req_alert(req, "Python failed to create Future object");
         nxt_python_print_exception();
@@ -130,7 +134,7 @@ nxt_py_asgi_http_receive(PyObject *self, PyObject *none)
     }
 
     if (msg != Py_None) {
-        return nxt_py_asgi_set_result_soon(req, future, msg);
+        return nxt_py_asgi_set_result_soon(req, ctx_data, future, msg);
     }
 
     http->receive_future = future;
@@ -329,11 +333,12 @@ nxt_py_asgi_http_response_start(nxt_py_asgi_http_t *http, PyObject *dict)
 static PyObject *
 nxt_py_asgi_http_response_body(nxt_py_asgi_http_t *http, PyObject *dict)
 {
-    int         rc;
-    char        *body_str;
-    ssize_t     sent;
-    PyObject    *body, *more_body, *future;
-    Py_ssize_t  body_len, body_off;
+    int                     rc;
+    char                    *body_str;
+    ssize_t                 sent;
+    PyObject                *body, *more_body, *future;
+    Py_ssize_t              body_len, body_off;
+    nxt_py_asgi_ctx_data_t  *ctx_data;
 
     body = PyDict_GetItem(dict, nxt_py_body_str);
     if (nxt_slow_path(body != NULL && !PyBytes_Check(body))) {
@@ -371,6 +376,8 @@ nxt_py_asgi_http_response_body(nxt_py_asgi_http_t *http, PyObject *dict)
 
         body_off = 0;
 
+        ctx_data = http->req->ctx->data;
+
         while (body_len > 0) {
             sent = nxt_unit_response_write_nb(http->req, body_str, body_len, 0);
             if (nxt_slow_path(sent < 0)) {
@@ -382,7 +389,8 @@ nxt_py_asgi_http_response_body(nxt_py_asgi_http_t *http, PyObject *dict)
                                    "out of shared memory, %d",
                                    (int) body_len);
 
-                future = PyObject_CallObject(nxt_py_loop_create_future, NULL);
+                future = PyObject_CallObject(ctx_data->loop_create_future,
+                                             NULL);
                 if (nxt_slow_path(future == NULL)) {
                     nxt_unit_req_alert(http->req,
                                        "Python failed to create Future object");
@@ -396,7 +404,7 @@ nxt_py_asgi_http_response_body(nxt_py_asgi_http_t *http, PyObject *dict)
                 Py_INCREF(http->send_body);
                 http->send_body_off = body_off;
 
-                nxt_queue_insert_tail(&nxt_py_asgi_drain_queue, &http->link);
+                nxt_py_asgi_drain_wait(http->req, &http->link);
 
                 http->send_future = future;
                 Py_INCREF(http->send_future);
diff --git a/src/python/nxt_python_asgi_lifespan.c b/src/python/nxt_python_asgi_lifespan.c
index 14d0ee97..6910d2e8 100644
--- a/src/python/nxt_python_asgi_lifespan.c
+++ b/src/python/nxt_python_asgi_lifespan.c
@@ -15,15 +15,16 @@
 
 typedef struct  {
     PyObject_HEAD
-    int       disabled;
-    int       startup_received;
-    int       startup_sent;
-    int       shutdown_received;
-    int       shutdown_sent;
-    int       shutdown_called;
-    PyObject  *startup_future;
-    PyObject  *shutdown_future;
-    PyObject  *receive_future;
+    nxt_py_asgi_ctx_data_t  *ctx_data;
+    int                     disabled;
+    int                     startup_received;
+    int                     startup_sent;
+    int                     shutdown_received;
+    int                     shutdown_sent;
+    int                     shutdown_called;
+    PyObject                *startup_future;
+    PyObject                *shutdown_future;
+    PyObject                *receive_future;
 } nxt_py_asgi_lifespan_t;
 
 
@@ -39,8 +40,6 @@ static PyObject *nxt_py_asgi_lifespan_disable(nxt_py_asgi_lifespan_t *lifespan);
 static PyObject *nxt_py_asgi_lifespan_done(PyObject *self, PyObject *future);
 
 
-static nxt_py_asgi_lifespan_t  *nxt_py_lifespan;
-
 static PyMethodDef nxt_py_asgi_lifespan_methods[] = {
     { "receive",   nxt_py_asgi_lifespan_receive, METH_NOARGS, 0 },
     { "send",      nxt_py_asgi_lifespan_send,    METH_O,      0 },
@@ -67,46 +66,46 @@ static PyTypeObject nxt_py_asgi_lifespan_type = {
 };
 
 
-nxt_int_t
-nxt_py_asgi_lifespan_startup(nxt_task_t *task)
+int
+nxt_py_asgi_lifespan_startup(nxt_py_asgi_ctx_data_t *ctx_data)
 {
+    int                     rc;
     PyObject                *scope, *res, *py_task, *receive, *send, *done;
-    nxt_int_t               rc;
     nxt_py_asgi_lifespan_t  *lifespan;
 
     if (nxt_slow_path(PyType_Ready(&nxt_py_asgi_lifespan_type) != 0)) {
-        nxt_alert(task,
+        nxt_unit_alert(NULL,
                  "Python failed to initialize the 'asgi_lifespan' type object");
-        return NXT_ERROR;
+        return NXT_UNIT_ERROR;
     }
 
     lifespan = PyObject_New(nxt_py_asgi_lifespan_t, &nxt_py_asgi_lifespan_type);
     if (nxt_slow_path(lifespan == NULL)) {
-        nxt_alert(task, "Python failed to create lifespan object");
-        return NXT_ERROR;
+        nxt_unit_alert(NULL, "Python failed to create lifespan object");
+        return NXT_UNIT_ERROR;
     }
 
-    rc = NXT_ERROR;
+    rc = NXT_UNIT_ERROR;
 
     receive = PyObject_GetAttrString((PyObject *) lifespan, "receive");
     if (nxt_slow_path(receive == NULL)) {
-        nxt_alert(task, "Python failed to get 'receive' method");
+        nxt_unit_alert(NULL, "Python failed to get 'receive' method");
         goto release_lifespan;
     }
 
     send = PyObject_GetAttrString((PyObject *) lifespan, "send");
     if (nxt_slow_path(receive == NULL)) {
-        nxt_alert(task, "Python failed to get 'send' method");
+        nxt_unit_alert(NULL, "Python failed to get 'send' method");
         goto release_receive;
     }
 
     done = PyObject_GetAttrString((PyObject *) lifespan, "_done");
     if (nxt_slow_path(receive == NULL)) {
-        nxt_alert(task, "Python failed to get '_done' method");
+        nxt_unit_alert(NULL, "Python failed to get '_done' method");
         goto release_send;
     }
 
-    lifespan->startup_future = PyObject_CallObject(nxt_py_loop_create_future,
+    lifespan->startup_future = PyObject_CallObject(ctx_data->loop_create_future,
                                                    NULL);
     if (nxt_slow_path(lifespan->startup_future == NULL)) {
         nxt_unit_alert(NULL, "Python failed to create Future object");
@@ -115,6 +114,7 @@ nxt_py_asgi_lifespan_startup(nxt_task_t *task)
         goto release_done;
     }
 
+    lifespan->ctx_data = ctx_data;
     lifespan->disabled = 0;
     lifespan->startup_received = 0;
     lifespan->startup_sent = 0;
@@ -132,21 +132,20 @@ nxt_py_asgi_lifespan_startup(nxt_task_t *task)
     res = PyObject_CallFunctionObjArgs(nxt_py_application,
                                        scope, receive, send, NULL);
     if (nxt_slow_path(res == NULL)) {
-        nxt_log(task, NXT_LOG_ERR, "Python failed to call the application");
+        nxt_unit_error(NULL, "Python failed to call the application");
         nxt_python_print_exception();
         goto release_scope;
     }
 
     if (nxt_slow_path(!PyCoro_CheckExact(res))) {
-        nxt_log(task, NXT_LOG_ERR,
-                "Application result type is not a coroutine");
+        nxt_unit_error(NULL, "Application result type is not a coroutine");
         Py_DECREF(res);
         goto release_scope;
     }
 
-    py_task = PyObject_CallFunctionObjArgs(nxt_py_loop_create_task, res, NULL);
+    py_task = PyObject_CallFunctionObjArgs(ctx_data->loop_create_task, res, NULL);
     if (nxt_slow_path(py_task == NULL)) {
-        nxt_log(task, NXT_LOG_ERR, "Python failed to call the create_task");
+        nxt_unit_alert(NULL, "Python failed to call the create_task");
         nxt_python_print_exception();
         Py_DECREF(res);
         goto release_scope;
@@ -157,18 +156,17 @@ nxt_py_asgi_lifespan_startup(nxt_task_t *task)
     res = PyObject_CallMethodObjArgs(py_task, nxt_py_add_done_callback_str,
                                      done, NULL);
     if (nxt_slow_path(res == NULL)) {
-        nxt_log(task, NXT_LOG_ERR,
-                              "Python failed to call 'task.add_done_callback'");
+        nxt_unit_alert(NULL, "Python failed to call 'task.add_done_callback'");
         nxt_python_print_exception();
         goto release_task;
     }
 
     Py_DECREF(res);
 
-    res = PyObject_CallFunctionObjArgs(nxt_py_loop_run_until_complete,
+    res = PyObject_CallFunctionObjArgs(ctx_data->loop_run_until_complete,
                                        lifespan->startup_future, NULL);
     if (nxt_slow_path(res == NULL)) {
-        nxt_alert(task, "Python failed to call loop.run_until_complete");
+        nxt_unit_alert(NULL, "Python failed to call loop.run_until_complete");
         nxt_python_print_exception();
         goto release_task;
     }
@@ -176,10 +174,10 @@ nxt_py_asgi_lifespan_startup(nxt_task_t *task)
     Py_DECREF(res);
 
     if (lifespan->startup_sent == 1 || lifespan->disabled) {
-        nxt_py_lifespan = lifespan;
-        Py_INCREF(nxt_py_lifespan);
+        ctx_data->lifespan = (PyObject *) lifespan;
+        Py_INCREF(ctx_data->lifespan);
 
-        rc = NXT_OK;
+        rc = NXT_UNIT_OK;
     }
 
 release_task:
@@ -201,17 +199,21 @@ release_lifespan:
 }
 
 
-nxt_int_t
-nxt_py_asgi_lifespan_shutdown(void)
+int
+nxt_py_asgi_lifespan_shutdown(nxt_unit_ctx_t *ctx)
 {
     PyObject                *msg, *future, *res;
     nxt_py_asgi_lifespan_t  *lifespan;
+    nxt_py_asgi_ctx_data_t  *ctx_data;
+
+    ctx_data = ctx->data;
+
+    lifespan = (nxt_py_asgi_lifespan_t *) ctx_data->lifespan;
 
-    if (nxt_slow_path(nxt_py_lifespan == NULL || nxt_py_lifespan->disabled)) {
-        return NXT_OK;
+    if (nxt_slow_path(lifespan == NULL || lifespan->disabled)) {
+        return NXT_UNIT_OK;
     }
 
-    lifespan = nxt_py_lifespan;
     lifespan->shutdown_called = 1;
 
     if (lifespan->receive_future != NULL) {
@@ -231,29 +233,29 @@ nxt_py_asgi_lifespan_shutdown(void)
     }
 
     if (lifespan->shutdown_sent) {
-        return NXT_OK;
+        return NXT_UNIT_OK;
     }
 
-    lifespan->shutdown_future = PyObject_CallObject(nxt_py_loop_create_future,
+    lifespan->shutdown_future = PyObject_CallObject(ctx_data->loop_create_future,
                                                     NULL);
     if (nxt_slow_path(lifespan->shutdown_future == NULL)) {
         nxt_unit_alert(NULL, "Python failed to create Future object");
         nxt_python_print_exception();
-        return NXT_ERROR;
+        return NXT_UNIT_ERROR;
     }
 
-    res = PyObject_CallFunctionObjArgs(nxt_py_loop_run_until_complete,
+    res = PyObject_CallFunctionObjArgs(ctx_data->loop_run_until_complete,
                                        lifespan->shutdown_future, NULL);
     if (nxt_slow_path(res == NULL)) {
         nxt_unit_alert(NULL, "Python failed to call loop.run_until_complete");
         nxt_python_print_exception();
-        return NXT_ERROR;
+        return NXT_UNIT_ERROR;
     }
 
     Py_DECREF(res);
     Py_CLEAR(lifespan->shutdown_future);
 
-    return NXT_OK;
+    return NXT_UNIT_OK;
 }
 
 
@@ -262,12 +264,14 @@ nxt_py_asgi_lifespan_receive(PyObject *self, PyObject *none)
 {
     PyObject                *msg, *future;
     nxt_py_asgi_lifespan_t  *lifespan;
+    nxt_py_asgi_ctx_data_t  *ctx_data;
 
     lifespan = (nxt_py_asgi_lifespan_t *) self;
+    ctx_data = lifespan->ctx_data;
 
     nxt_unit_debug(NULL, "asgi_lifespan_receive");
 
-    future = PyObject_CallObject(nxt_py_loop_create_future, NULL);
+    future = PyObject_CallObject(ctx_data->loop_create_future, NULL);
     if (nxt_slow_path(future == NULL)) {
         nxt_unit_alert(NULL, "Python failed to create Future object");
         nxt_python_print_exception();
@@ -281,7 +285,7 @@ nxt_py_asgi_lifespan_receive(PyObject *self, PyObject *none)
 
         msg = nxt_py_asgi_new_msg(NULL, nxt_py_lifespan_startup_str);
 
-        return nxt_py_asgi_set_result_soon(NULL, future, msg);
+        return nxt_py_asgi_set_result_soon(NULL, ctx_data, future, msg);
     }
 
     if (lifespan->shutdown_called && !lifespan->shutdown_received) {
@@ -289,7 +293,7 @@ nxt_py_asgi_lifespan_receive(PyObject *self, PyObject *none)
 
         msg = nxt_py_asgi_new_msg(NULL, nxt_py_lifespan_shutdown_str);
 
-        return nxt_py_asgi_set_result_soon(NULL, future, msg);
+        return nxt_py_asgi_set_result_soon(NULL, ctx_data, future, msg);
     }
 
     Py_INCREF(future);
diff --git a/src/python/nxt_python_asgi_str.c b/src/python/nxt_python_asgi_str.c
index 37fa7f04..34422973 100644
--- a/src/python/nxt_python_asgi_str.c
+++ b/src/python/nxt_python_asgi_str.c
@@ -124,7 +124,7 @@ static nxt_python_string_t nxt_py_asgi_strings[] = {
 };
 
 
-nxt_int_t
+int
 nxt_py_asgi_str_init(void)
 {
     return nxt_python_init_strings(nxt_py_asgi_strings);
diff --git a/src/python/nxt_python_asgi_str.h b/src/python/nxt_python_asgi_str.h
index 3f389c62..92969fd2 100644
--- a/src/python/nxt_python_asgi_str.h
+++ b/src/python/nxt_python_asgi_str.h
@@ -62,7 +62,7 @@ extern PyObject  *nxt_py_ws_str;
 extern PyObject  *nxt_py_wss_str;
 
 
-nxt_int_t nxt_py_asgi_str_init(void);
+int nxt_py_asgi_str_init(void);
 void nxt_py_asgi_str_done(void);
 
 
diff --git a/src/python/nxt_python_asgi_websocket.c b/src/python/nxt_python_asgi_websocket.c
index 5a27b588..fc7d9fa4 100644
--- a/src/python/nxt_python_asgi_websocket.c
+++ b/src/python/nxt_python_asgi_websocket.c
@@ -98,16 +98,16 @@ static uint64_t  nxt_py_asgi_ws_max_frame_size = 1024 * 1024;
 static uint64_t  nxt_py_asgi_ws_max_buffer_size = 10 * 1024 * 1024;
 
 
-nxt_int_t
-nxt_py_asgi_websocket_init(nxt_task_t *task)
+int
+nxt_py_asgi_websocket_init(void)
 {
     if (nxt_slow_path(PyType_Ready(&nxt_py_asgi_websocket_type) != 0)) {
-        nxt_alert(task,
+        nxt_unit_alert(NULL,
               "Python failed to initialize the \"asgi_websocket\" type object");
-        return NXT_ERROR;
+        return NXT_UNIT_ERROR;
     }
 
-    return NXT_OK;
+    return NXT_UNIT_OK;
 }
 
 
@@ -137,6 +137,7 @@ static PyObject *
 nxt_py_asgi_websocket_receive(PyObject *self, PyObject *none)
 {
     PyObject                 *future, *msg;
+    nxt_py_asgi_ctx_data_t   *ctx_data;
     nxt_py_asgi_websocket_t  *ws;
 
     ws = (nxt_py_asgi_websocket_t *) self;
@@ -160,7 +161,9 @@ nxt_py_asgi_websocket_receive(PyObject *self, PyObject *none)
                             "WebSocket already closed");
     }
 
-    future = PyObject_CallObject(nxt_py_loop_create_future, NULL);
+    ctx_data = ws->req->ctx->data;
+
+    future = PyObject_CallObject(ctx_data->loop_create_future, NULL);
     if (nxt_slow_path(future == NULL)) {
         nxt_unit_req_alert(ws->req, "Python failed to create Future object");
         nxt_python_print_exception();
@@ -174,19 +177,19 @@ nxt_py_asgi_websocket_receive(PyObject *self, PyObject *none)
 
         msg = nxt_py_asgi_new_msg(ws->req, nxt_py_websocket_connect_str);
 
-        return nxt_py_asgi_set_result_soon(ws->req, future, msg);
+        return nxt_py_asgi_set_result_soon(ws->req, ctx_data, future, msg);
     }
 
     if (ws->pending_fins > 0) {
         msg = nxt_py_asgi_websocket_pop_msg(ws, NULL);
 
-        return nxt_py_asgi_set_result_soon(ws->req, future, msg);
+        return nxt_py_asgi_set_result_soon(ws->req, ctx_data, future, msg);
     }
 
     if (nxt_slow_path(ws->state == NXT_WS_DISCONNECTED)) {
         msg = nxt_py_asgi_websocket_disconnect_msg(ws);
 
-        return nxt_py_asgi_set_result_soon(ws->req, future, msg);
+        return nxt_py_asgi_set_result_soon(ws->req, ctx_data, future, msg);
     }
 
     ws->receive_future = future;
diff --git a/src/python/nxt_python_wsgi.c b/src/python/nxt_python_wsgi.c
index 8f692941..da7b183c 100644
--- a/src/python/nxt_python_wsgi.c
+++ b/src/python/nxt_python_wsgi.c
@@ -38,55 +38,57 @@
  */
 
 
-typedef struct nxt_python_run_ctx_s  nxt_python_run_ctx_t;
-
 typedef struct {
     PyObject_HEAD
-} nxt_py_input_t;
 
+    uint64_t                 content_length;
+    uint64_t                 bytes_sent;
+    PyObject                 *environ;
+    PyObject                 *start_resp;
+    PyObject                 *write;
+    nxt_unit_request_info_t  *req;
+    PyThreadState            *thread_state;
+}  nxt_python_ctx_t;
 
-typedef struct {
-    PyObject_HEAD
-} nxt_py_error_t;
+
+static int nxt_python_wsgi_ctx_data_alloc(void **pdata);
+static void nxt_python_wsgi_ctx_data_free(void *data);
+static int nxt_python_wsgi_run(nxt_unit_ctx_t *ctx);
+static void nxt_python_wsgi_done(void);
 
 static void nxt_python_request_handler(nxt_unit_request_info_t *req);
 
-static PyObject *nxt_python_create_environ(nxt_task_t *task);
-static PyObject *nxt_python_get_environ(nxt_python_run_ctx_t *ctx);
-static int nxt_python_add_sptr(nxt_python_run_ctx_t *ctx, PyObject *name,
+static PyObject *nxt_python_create_environ(nxt_python_app_conf_t *c);
+static PyObject *nxt_python_get_environ(nxt_python_ctx_t *pctx);
+static int nxt_python_add_sptr(nxt_python_ctx_t *pctx, PyObject *name,
     nxt_unit_sptr_t *sptr, uint32_t size);
-static int nxt_python_add_field(nxt_python_run_ctx_t *ctx,
+static int nxt_python_add_field(nxt_python_ctx_t *pctx,
     nxt_unit_field_t *field, int n, uint32_t vl);
 static PyObject *nxt_python_field_name(const char *name, uint8_t len);
 static PyObject *nxt_python_field_value(nxt_unit_field_t *f, int n,
     uint32_t vl);
-static int nxt_python_add_obj(nxt_python_run_ctx_t *ctx, PyObject *name,
+static int nxt_python_add_obj(nxt_python_ctx_t *pctx, PyObject *name,
     PyObject *value);
 
 static PyObject *nxt_py_start_resp(PyObject *self, PyObject *args);
-static int nxt_python_response_add_field(nxt_python_run_ctx_t *ctx,
+static int nxt_python_response_add_field(nxt_python_ctx_t *pctx,
     PyObject *name, PyObject *value, int i);
 static int nxt_python_str_buf(PyObject *str, char **buf, uint32_t *len,
     PyObject **bytes);
 static PyObject *nxt_py_write(PyObject *self, PyObject *args);
 
-static void nxt_py_input_dealloc(nxt_py_input_t *self);
-static PyObject *nxt_py_input_read(nxt_py_input_t *self, PyObject *args);
-static PyObject *nxt_py_input_readline(nxt_py_input_t *self, PyObject *args);
-static PyObject *nxt_py_input_getline(nxt_python_run_ctx_t *ctx, size_t size);
-static PyObject *nxt_py_input_readlines(nxt_py_input_t *self, PyObject *args);
+static void nxt_py_input_dealloc(nxt_python_ctx_t *pctx);
+static PyObject *nxt_py_input_read(nxt_python_ctx_t *pctx, PyObject *args);
+static PyObject *nxt_py_input_readline(nxt_python_ctx_t *pctx,
+    PyObject *args);
+static PyObject *nxt_py_input_getline(nxt_python_ctx_t *pctx, size_t size);
+static PyObject *nxt_py_input_readlines(nxt_python_ctx_t *self,
+    PyObject *args);
 
-static PyObject *nxt_py_input_iter(PyObject *self);
-static PyObject *nxt_py_input_next(PyObject *self);
+static PyObject *nxt_py_input_iter(PyObject *pctx);
+static PyObject *nxt_py_input_next(PyObject *pctx);
 
-static int nxt_python_write(nxt_python_run_ctx_t *ctx, PyObject *bytes);
-
-struct nxt_python_run_ctx_s {
-    uint64_t                 content_length;
-    uint64_t                 bytes_sent;
-    PyObject                 *environ;
-    nxt_unit_request_info_t  *req;
-};
+static int nxt_python_write(nxt_python_ctx_t *pctx, PyObject *bytes);
 
 
 static PyMethodDef nxt_py_start_resp_method[] = {
@@ -111,7 +113,7 @@ static PyTypeObject nxt_py_input_type = {
     PyVarObject_HEAD_INIT(NULL, 0)
 
     .tp_name      = "unit._input",
-    .tp_basicsize = sizeof(nxt_py_input_t),
+    .tp_basicsize = sizeof(nxt_python_ctx_t),
     .tp_dealloc   = (destructor) nxt_py_input_dealloc,
     .tp_flags     = Py_TPFLAGS_DEFAULT,
     .tp_doc       = "unit input object.",
@@ -121,12 +123,7 @@ static PyTypeObject nxt_py_input_type = {
 };
 
 
-static PyObject           *nxt_py_start_resp_obj;
-static PyObject           *nxt_py_write_obj;
-static PyObject           *nxt_py_environ_ptyp;
-
-static PyThreadState         *nxt_python_thread_state;
-static nxt_python_run_ctx_t  *nxt_python_run_ctx;
+static PyObject  *nxt_py_environ_ptyp;
 
 static PyObject  *nxt_py_80_str;
 static PyObject  *nxt_py_close_str;
@@ -143,6 +140,7 @@ static PyObject  *nxt_py_server_addr_str;
 static PyObject  *nxt_py_server_name_str;
 static PyObject  *nxt_py_server_port_str;
 static PyObject  *nxt_py_server_protocol_str;
+static PyObject  *nxt_py_wsgi_input_str;
 static PyObject  *nxt_py_wsgi_uri_scheme_str;
 
 static nxt_python_string_t nxt_python_strings[] = {
@@ -161,82 +159,132 @@ static nxt_python_string_t nxt_python_strings[] = {
     { nxt_string("SERVER_NAME"), &nxt_py_server_name_str },
     { nxt_string("SERVER_PORT"), &nxt_py_server_port_str },
     { nxt_string("SERVER_PROTOCOL"), &nxt_py_server_protocol_str },
+    { nxt_string("wsgi.input"), &nxt_py_wsgi_input_str },
     { nxt_string("wsgi.url_scheme"), &nxt_py_wsgi_uri_scheme_str },
     { nxt_null_string, NULL },
 };
 
+static nxt_python_proto_t  nxt_py_wsgi_proto = {
+    .ctx_data_alloc = nxt_python_wsgi_ctx_data_alloc,
+    .ctx_data_free  = nxt_python_wsgi_ctx_data_free,
+    .run            = nxt_python_wsgi_run,
+    .done           = nxt_python_wsgi_done,
+};
+
 
-nxt_int_t
-nxt_python_wsgi_init(nxt_task_t *task, nxt_unit_init_t *init)
+int
+nxt_python_wsgi_init(nxt_unit_init_t *init, nxt_python_proto_t *proto)
 {
     PyObject  *obj;
 
     obj = NULL;
 
-    if (nxt_slow_path(nxt_python_init_strings(nxt_python_strings) != NXT_OK)) {
-        nxt_alert(task, "Python failed to init string objects");
+    if (nxt_slow_path(nxt_python_init_strings(nxt_python_strings)
+                      != NXT_UNIT_OK))
+    {
+        nxt_unit_alert(NULL, "Python failed to init string objects");
         goto fail;
     }
 
-    obj = PyCFunction_New(nxt_py_start_resp_method, NULL);
+    obj = nxt_python_create_environ(init->data);
     if (nxt_slow_path(obj == NULL)) {
-        nxt_alert(task,
-                "Python failed to initialize the \"start_response\" function");
         goto fail;
     }
 
-    nxt_py_start_resp_obj = obj;
+    nxt_py_environ_ptyp = obj;
+    obj = NULL;
+
+    init->callbacks.request_handler = nxt_python_request_handler;
+
+    *proto = nxt_py_wsgi_proto;
 
-    obj = PyCFunction_New(nxt_py_write_method, NULL);
-    if (nxt_slow_path(obj == NULL)) {
-        nxt_alert(task, "Python failed to initialize the \"write\" function");
-        goto fail;
+    return NXT_UNIT_OK;
+
+fail:
+
+    Py_XDECREF(obj);
+
+    return NXT_UNIT_ERROR;
+}
+
+
+static int
+nxt_python_wsgi_ctx_data_alloc(void **pdata)
+{
+    nxt_python_ctx_t  *pctx;
+
+    pctx = PyObject_New(nxt_python_ctx_t, &nxt_py_input_type);
+    if (nxt_slow_path(pctx == NULL)) {
+        nxt_unit_alert(NULL,
+                       "Python failed to create the \"wsgi.input\" object");
+        return NXT_UNIT_ERROR;
     }
 
-    nxt_py_write_obj = obj;
+    pctx->write = NULL;
 
-    obj = nxt_python_create_environ(task);
-    if (nxt_slow_path(obj == NULL)) {
+    pctx->start_resp = PyCFunction_New(nxt_py_start_resp_method,
+                                       (PyObject *) pctx);
+    if (nxt_slow_path(pctx->start_resp == NULL)) {
+        nxt_unit_alert(NULL,
+                "Python failed to initialize the \"start_response\" function");
         goto fail;
     }
 
-    nxt_py_environ_ptyp = obj;
-    obj = NULL;
+    pctx->write = PyCFunction_New(nxt_py_write_method, (PyObject *) pctx);
+    if (nxt_slow_path(pctx->write == NULL)) {
+        nxt_unit_alert(NULL,
+                       "Python failed to initialize the \"write\" function");
+        goto fail;
+    }
 
-    init->callbacks.request_handler = nxt_python_request_handler;
+    *pdata = pctx;
 
-    return NXT_OK;
+    return NXT_UNIT_OK;
 
 fail:
 
-    Py_XDECREF(obj);
+    nxt_python_wsgi_ctx_data_free(pctx);
 
-    return NXT_ERROR;
+    return NXT_UNIT_ERROR;
 }
 
 
-int
+static void
+nxt_python_wsgi_ctx_data_free(void *data)
+{
+    nxt_python_ctx_t  *pctx;
+
+    pctx = data;
+
+    Py_XDECREF(pctx->start_resp);
+    Py_XDECREF(pctx->write);
+    Py_XDECREF(pctx);
+}
+
+
+static int
 nxt_python_wsgi_run(nxt_unit_ctx_t *ctx)
 {
-    int  rc;
+    int               rc;
+    nxt_python_ctx_t  *pctx;
 
-    nxt_python_thread_state = PyEval_SaveThread();
+    pctx = ctx->data;
+
+    pctx->thread_state = PyEval_SaveThread();
 
     rc = nxt_unit_run(ctx);
 
-    PyEval_RestoreThread(nxt_python_thread_state);
+    PyEval_RestoreThread(pctx->thread_state);
 
     return rc;
 }
 
 
-void
+static void
 nxt_python_wsgi_done(void)
 {
     nxt_python_done_strings(nxt_python_strings);
 
-    Py_XDECREF(nxt_py_start_resp_obj);
-    Py_XDECREF(nxt_py_write_obj);
     Py_XDECREF(nxt_py_environ_ptyp);
 }
 
@@ -244,14 +292,20 @@ nxt_python_wsgi_done(void)
 static void
 nxt_python_request_handler(nxt_unit_request_info_t *req)
 {
-    int                   rc;
-    PyObject              *environ, *args, *response, *iterator, *item;
-    PyObject              *close, *result;
-    nxt_python_run_ctx_t  run_ctx = {-1, 0, NULL, req};
+    int               rc;
+    PyObject          *environ, *args, *response, *iterator, *item;
+    PyObject          *close, *result;
+    nxt_python_ctx_t  *pctx;
 
-    PyEval_RestoreThread(nxt_python_thread_state);
+    pctx = req->ctx->data;
 
-    environ = nxt_python_get_environ(&run_ctx);
+    pctx->content_length = -1;
+    pctx->bytes_sent = 0;
+    pctx->req = req;
+
+    PyEval_RestoreThread(pctx->thread_state);
+
+    environ = nxt_python_get_environ(pctx);
     if (nxt_slow_path(environ == NULL)) {
         rc = NXT_UNIT_ERROR;
         goto done;
@@ -269,10 +323,8 @@ nxt_python_request_handler(nxt_unit_request_info_t *req)
 
     PyTuple_SET_ITEM(args, 0, environ);
 
-    Py_INCREF(nxt_py_start_resp_obj);
-    PyTuple_SET_ITEM(args, 1, nxt_py_start_resp_obj);
-
-    nxt_python_run_ctx = &run_ctx;
+    Py_INCREF(pctx->start_resp);
+    PyTuple_SET_ITEM(args, 1, pctx->start_resp);
 
     response = PyObject_CallObject(nxt_py_application, args);
 
@@ -288,7 +340,7 @@ nxt_python_request_handler(nxt_unit_request_info_t *req)
 
     /* Shortcut: avoid iterate over response string symbols. */
     if (PyBytes_Check(response)) {
-        rc = nxt_python_write(&run_ctx, response);
+        rc = nxt_python_write(pctx, response);
 
     } else {
         iterator = PyObject_GetIter(response);
@@ -296,7 +348,7 @@ nxt_python_request_handler(nxt_unit_request_info_t *req)
         if (nxt_fast_path(iterator != NULL)) {
             rc = NXT_UNIT_OK;
 
-            while (run_ctx.bytes_sent < run_ctx.content_length) {
+            while (pctx->bytes_sent < pctx->content_length) {
                 item = PyIter_Next(iterator);
 
                 if (item == NULL) {
@@ -312,7 +364,7 @@ nxt_python_request_handler(nxt_unit_request_info_t *req)
                 }
 
                 if (nxt_fast_path(PyBytes_Check(item))) {
-                    rc = nxt_python_write(&run_ctx, item);
+                    rc = nxt_python_write(pctx, item);
 
                 } else {
                     nxt_unit_req_error(req, "the application returned "
@@ -361,29 +413,31 @@ nxt_python_request_handler(nxt_unit_request_info_t *req)
 
 done:
 
-    nxt_python_thread_state = PyEval_SaveThread();
+    pctx->thread_state = PyEval_SaveThread();
+
+    pctx->req = NULL;
 
-    nxt_python_run_ctx = NULL;
     nxt_unit_request_done(req, rc);
 }
 
 
 static PyObject *
-nxt_python_create_environ(nxt_task_t *task)
+nxt_python_create_environ(nxt_python_app_conf_t *c)
 {
     PyObject  *obj, *err, *environ;
 
     environ = PyDict_New();
 
     if (nxt_slow_path(environ == NULL)) {
-        nxt_alert(task, "Python failed to create the \"environ\" dictionary");
+        nxt_unit_alert(NULL,
+                       "Python failed to create the \"environ\" dictionary");
         return NULL;
     }
 
     obj = PyString_FromStringAndSize((char *) nxt_server.start,
                                      nxt_server.length);
     if (nxt_slow_path(obj == NULL)) {
-        nxt_alert(task,
+        nxt_unit_alert(NULL,
               "Python failed to create the \"SERVER_SOFTWARE\" environ value");
         goto fail;
     }
@@ -391,7 +445,7 @@ nxt_python_create_environ(nxt_task_t *task)
     if (nxt_slow_path(PyDict_SetItemString(environ, "SERVER_SOFTWARE", obj)
         != 0))
     {
-        nxt_alert(task,
+        nxt_unit_alert(NULL,
                   "Python failed to set the \"SERVER_SOFTWARE\" environ value");
         goto fail;
     }
@@ -401,15 +455,15 @@ nxt_python_create_environ(nxt_task_t *task)
     obj = Py_BuildValue("(ii)", 1, 0);
 
     if (nxt_slow_path(obj == NULL)) {
-        nxt_alert(task,
+        nxt_unit_alert(NULL,
                   "Python failed to build the \"wsgi.version\" environ value");
         goto fail;
     }
 
     if (nxt_slow_path(PyDict_SetItemString(environ, "wsgi.version", obj) != 0))
     {
-        nxt_alert(task,
-                  "Python failed to set the \"wsgi.version\" environ value");
+        nxt_unit_alert(NULL,
+                    "Python failed to set the \"wsgi.version\" environ value");
         goto fail;
     }
 
@@ -418,10 +472,10 @@ nxt_python_create_environ(nxt_task_t *task)
 
 
     if (nxt_slow_path(PyDict_SetItemString(environ, "wsgi.multithread",
-                                           Py_False)
+                                           c->threads > 1 ? Py_True : Py_False)
         != 0))
     {
-        nxt_alert(task,
+        nxt_unit_alert(NULL,
                 "Python failed to set the \"wsgi.multithread\" environ value");
         goto fail;
     }
@@ -430,7 +484,7 @@ nxt_python_create_environ(nxt_task_t *task)
                                            Py_True)
         != 0))
     {
-        nxt_alert(task,
+        nxt_unit_alert(NULL,
                "Python failed to set the \"wsgi.multiprocess\" environ value");
         goto fail;
     }
@@ -439,46 +493,30 @@ nxt_python_create_environ(nxt_task_t *task)
                                            Py_False)
         != 0))
     {
-        nxt_alert(task,
+        nxt_unit_alert(NULL,
                   "Python failed to set the \"wsgi.run_once\" environ value");
         goto fail;
     }
 
 
     if (nxt_slow_path(PyType_Ready(&nxt_py_input_type) != 0)) {
-        nxt_alert(task,
+        nxt_unit_alert(NULL,
                   "Python failed to initialize the \"wsgi.input\" type object");
         goto fail;
     }
 
-    obj = (PyObject *) PyObject_New(nxt_py_input_t, &nxt_py_input_type);
-
-    if (nxt_slow_path(obj == NULL)) {
-        nxt_alert(task, "Python failed to create the \"wsgi.input\" object");
-        goto fail;
-    }
-
-    if (nxt_slow_path(PyDict_SetItemString(environ, "wsgi.input", obj) != 0)) {
-        nxt_alert(task,
-                  "Python failed to set the \"wsgi.input\" environ value");
-        goto fail;
-    }
-
-    Py_DECREF(obj);
-    obj = NULL;
-
 
     err = PySys_GetObject((char *) "stderr");
 
     if (nxt_slow_path(err == NULL)) {
-        nxt_alert(task, "Python failed to get \"sys.stderr\" object");
+        nxt_unit_alert(NULL, "Python failed to get \"sys.stderr\" object");
         goto fail;
     }
 
     if (nxt_slow_path(PyDict_SetItemString(environ, "wsgi.errors", err) != 0))
     {
-        nxt_alert(task,
-                  "Python failed to set the \"wsgi.errors\" environ value");
+        nxt_unit_alert(NULL,
+                      "Python failed to set the \"wsgi.errors\" environ value");
         goto fail;
     }
 
@@ -494,7 +532,7 @@ fail:
 
 
 static PyObject *
-nxt_python_get_environ(nxt_python_run_ctx_t *ctx)
+nxt_python_get_environ(nxt_python_ctx_t *pctx)
 {
     int                 rc;
     uint32_t            i, j, vl;
@@ -504,15 +542,15 @@ nxt_python_get_environ(nxt_python_run_ctx_t *ctx)
 
     environ = PyDict_Copy(nxt_py_environ_ptyp);
     if (nxt_slow_path(environ == NULL)) {
-        nxt_unit_req_error(ctx->req,
+        nxt_unit_req_error(pctx->req,
                            "Python failed to copy the \"environ\" dictionary");
 
         return NULL;
     }
 
-    ctx->environ = environ;
+    pctx->environ = environ;
 
-    r = ctx->req->request;
+    r = pctx->req->request;
 
 #define RC(S)                                                                 \
     do {                                                                      \
@@ -522,36 +560,36 @@ nxt_python_get_environ(nxt_python_run_ctx_t *ctx)
         }                                                                     \
     } while(0)
 
-    RC(nxt_python_add_sptr(ctx, nxt_py_request_method_str, &r->method,
+    RC(nxt_python_add_sptr(pctx, nxt_py_request_method_str, &r->method,
                            r->method_length));
-    RC(nxt_python_add_sptr(ctx, nxt_py_request_uri_str, &r->target,
+    RC(nxt_python_add_sptr(pctx, nxt_py_request_uri_str, &r->target,
                            r->target_length));
-    RC(nxt_python_add_sptr(ctx, nxt_py_query_string_str, &r->query,
+    RC(nxt_python_add_sptr(pctx, nxt_py_query_string_str, &r->query,
                            r->query_length));
-    RC(nxt_python_add_sptr(ctx, nxt_py_path_info_str, &r->path,
+    RC(nxt_python_add_sptr(pctx, nxt_py_path_info_str, &r->path,
                            r->path_length));
 
-    RC(nxt_python_add_sptr(ctx, nxt_py_remote_addr_str, &r->remote,
+    RC(nxt_python_add_sptr(pctx, nxt_py_remote_addr_str, &r->remote,
                            r->remote_length));
-    RC(nxt_python_add_sptr(ctx, nxt_py_server_addr_str, &r->local,
+    RC(nxt_python_add_sptr(pctx, nxt_py_server_addr_str, &r->local,
                            r->local_length));
 
     if (r->tls) {
-        RC(nxt_python_add_obj(ctx, nxt_py_wsgi_uri_scheme_str,
+        RC(nxt_python_add_obj(pctx, nxt_py_wsgi_uri_scheme_str,
                               nxt_py_https_str));
     } else {
-        RC(nxt_python_add_obj(ctx, nxt_py_wsgi_uri_scheme_str,
+        RC(nxt_python_add_obj(pctx, nxt_py_wsgi_uri_scheme_str,
                               nxt_py_http_str));
     }
 
-    RC(nxt_python_add_sptr(ctx, nxt_py_server_protocol_str, &r->version,
+    RC(nxt_python_add_sptr(pctx, nxt_py_server_protocol_str, &r->version,
                            r->version_length));
 
-    RC(nxt_python_add_sptr(ctx, nxt_py_server_name_str, &r->server_name,
+    RC(nxt_python_add_sptr(pctx, nxt_py_server_name_str, &r->server_name,
                            r->server_name_length));
-    RC(nxt_python_add_obj(ctx, nxt_py_server_port_str, nxt_py_80_str));
+    RC(nxt_python_add_obj(pctx, nxt_py_server_port_str, nxt_py_80_str));
 
-    nxt_unit_request_group_dup_fields(ctx->req);
+    nxt_unit_request_group_dup_fields(pctx->req);
 
     for (i = 0; i < r->fields_count;) {
         f = r->fields + i;
@@ -569,7 +607,7 @@ nxt_python_get_environ(nxt_python_run_ctx_t *ctx)
             vl += 2 + f2->value_length;
         }
 
-        RC(nxt_python_add_field(ctx, f, j - i, vl));
+        RC(nxt_python_add_field(pctx, f, j - i, vl));
 
         i = j;
     }
@@ -577,19 +615,27 @@ nxt_python_get_environ(nxt_python_run_ctx_t *ctx)
     if (r->content_length_field != NXT_UNIT_NONE_FIELD) {
         f = r->fields + r->content_length_field;
 
-        RC(nxt_python_add_sptr(ctx, nxt_py_content_length_str, &f->value,
+        RC(nxt_python_add_sptr(pctx, nxt_py_content_length_str, &f->value,
                                f->value_length));
     }
 
     if (r->content_type_field != NXT_UNIT_NONE_FIELD) {
         f = r->fields + r->content_type_field;
 
-        RC(nxt_python_add_sptr(ctx, nxt_py_content_type_str, &f->value,
+        RC(nxt_python_add_sptr(pctx, nxt_py_content_type_str, &f->value,
                                f->value_length));
     }
 
 #undef RC
 
+    if (nxt_slow_path(PyDict_SetItem(environ, nxt_py_wsgi_input_str,
+                                     (PyObject *) pctx) != 0))
+    {
+        nxt_unit_req_error(pctx->req,
+                       "Python failed to set the \"wsgi.input\" environ value");
+        goto fail;
+    }
+
     return environ;
 
 fail:
@@ -601,7 +647,7 @@ fail:
 
 
 static int
-nxt_python_add_sptr(nxt_python_run_ctx_t *ctx, PyObject *name,
+nxt_python_add_sptr(nxt_python_ctx_t *pctx, PyObject *name,
     nxt_unit_sptr_t *sptr, uint32_t size)
 {
     char      *src;
@@ -611,7 +657,7 @@ nxt_python_add_sptr(nxt_python_run_ctx_t *ctx, PyObject *name,
 
     value = PyString_FromStringAndSize(src, size);
     if (nxt_slow_path(value == NULL)) {
-        nxt_unit_req_error(ctx->req,
+        nxt_unit_req_error(pctx->req,
                            "Python failed to create value string \"%.*s\"",
                            (int) size, src);
         nxt_python_print_exception();
@@ -619,8 +665,8 @@ nxt_python_add_sptr(nxt_python_run_ctx_t *ctx, PyObject *name,
         return NXT_UNIT_ERROR;
     }
 
-    if (nxt_slow_path(PyDict_SetItem(ctx->environ, name, value) != 0)) {
-        nxt_unit_req_error(ctx->req,
+    if (nxt_slow_path(PyDict_SetItem(pctx->environ, name, value) != 0)) {
+        nxt_unit_req_error(pctx->req,
                            "Python failed to set the \"%s\" environ value",
                            PyUnicode_AsUTF8(name));
         Py_DECREF(value);
@@ -635,7 +681,7 @@ nxt_python_add_sptr(nxt_python_run_ctx_t *ctx, PyObject *name,
 
 
 static int
-nxt_python_add_field(nxt_python_run_ctx_t *ctx, nxt_unit_field_t *field, int n,
+nxt_python_add_field(nxt_python_ctx_t *pctx, nxt_unit_field_t *field, int n,
     uint32_t vl)
 {
     char      *src;
@@ -645,7 +691,7 @@ nxt_python_add_field(nxt_python_run_ctx_t *ctx, nxt_unit_field_t *field, int n,
 
     name = nxt_python_field_name(src, field->name_length);
     if (nxt_slow_path(name == NULL)) {
-        nxt_unit_req_error(ctx->req,
+        nxt_unit_req_error(pctx->req,
                            "Python failed to create name string \"%.*s\"",
                            (int) field->name_length, src);
         nxt_python_print_exception();
@@ -656,7 +702,7 @@ nxt_python_add_field(nxt_python_run_ctx_t *ctx, nxt_unit_field_t *field, int n,
     value = nxt_python_field_value(field, n, vl);
 
     if (nxt_slow_path(value == NULL)) {
-        nxt_unit_req_error(ctx->req,
+        nxt_unit_req_error(pctx->req,
                            "Python failed to create value string \"%.*s\"",
                            (int) field->value_length,
                            (char *) nxt_unit_sptr_get(&field->value));
@@ -665,8 +711,8 @@ nxt_python_add_field(nxt_python_run_ctx_t *ctx, nxt_unit_field_t *field, int n,
         goto fail;
     }
 
-    if (nxt_slow_path(PyDict_SetItem(ctx->environ, name, value) != 0)) {
-        nxt_unit_req_error(ctx->req,
+    if (nxt_slow_path(PyDict_SetItem(pctx->environ, name, value) != 0)) {
+        nxt_unit_req_error(pctx->req,
                            "Python failed to set the \"%s\" environ value",
                            PyUnicode_AsUTF8(name));
         goto fail;
@@ -761,10 +807,10 @@ nxt_python_field_value(nxt_unit_field_t *f, int n, uint32_t vl)
 
 
 static int
-nxt_python_add_obj(nxt_python_run_ctx_t *ctx, PyObject *name, PyObject *value)
+nxt_python_add_obj(nxt_python_ctx_t *pctx, PyObject *name, PyObject *value)
 {
-    if (nxt_slow_path(PyDict_SetItem(ctx->environ, name, value) != 0)) {
-        nxt_unit_req_error(ctx->req,
+    if (nxt_slow_path(PyDict_SetItem(pctx->environ, name, value) != 0)) {
+        nxt_unit_req_error(pctx->req,
                            "Python failed to set the \"%s\" environ value",
                            PyUnicode_AsUTF8(name));
 
@@ -778,15 +824,15 @@ nxt_python_add_obj(nxt_python_run_ctx_t *ctx, PyObject *name, PyObject *value)
 static PyObject *
 nxt_py_start_resp(PyObject *self, PyObject *args)
 {
-    int                   rc, status;
-    char                  *status_str, *space_ptr;
-    uint32_t              status_len;
-    PyObject              *headers, *tuple, *string, *status_bytes;
-    Py_ssize_t            i, n, fields_size, fields_count;
-    nxt_python_run_ctx_t  *ctx;
-
-    ctx = nxt_python_run_ctx;
-    if (nxt_slow_path(ctx == NULL)) {
+    int               rc, status;
+    char              *status_str, *space_ptr;
+    uint32_t          status_len;
+    PyObject          *headers, *tuple, *string, *status_bytes;
+    Py_ssize_t        i, n, fields_size, fields_count;
+    nxt_python_ctx_t  *pctx;
+
+    pctx = (nxt_python_ctx_t *) self;
+    if (nxt_slow_path(pctx->req == NULL)) {
         return PyErr_Format(PyExc_RuntimeError,
                             "start_response() is called "
                             "outside of WSGI request processing");
@@ -851,7 +897,7 @@ nxt_py_start_resp(PyObject *self, PyObject *args)
         }
     }
 
-    ctx->content_length = -1;
+    pctx->content_length = -1;
 
     string = PyTuple_GET_ITEM(args, 0);
     rc = nxt_python_str_buf(string, &status_str, &status_len, &status_bytes);
@@ -877,7 +923,7 @@ nxt_py_start_resp(PyObject *self, PyObject *args)
      * ... applications can replace their originally intended output with error
      * output, up until the last possible moment.
      */
-    rc = nxt_unit_response_init(ctx->req, status, fields_count, fields_size);
+    rc = nxt_unit_response_init(pctx->req, status, fields_count, fields_size);
     if (nxt_slow_path(rc != NXT_UNIT_OK)) {
         return PyErr_Format(PyExc_RuntimeError,
                             "failed to allocate response object");
@@ -886,7 +932,7 @@ nxt_py_start_resp(PyObject *self, PyObject *args)
     for (i = 0; i < fields_count; i++) {
         tuple = PyList_GET_ITEM(headers, i);
 
-        rc = nxt_python_response_add_field(ctx, PyTuple_GET_ITEM(tuple, 0),
+        rc = nxt_python_response_add_field(pctx, PyTuple_GET_ITEM(tuple, 0),
                                            PyTuple_GET_ITEM(tuple, 1), i);
         if (nxt_slow_path(rc != NXT_UNIT_OK)) {
             return PyErr_Format(PyExc_RuntimeError,
@@ -907,21 +953,21 @@ nxt_py_start_resp(PyObject *self, PyObject *args)
      * possible exception to this rule is if the response headers explicitly
      * include a Content-Length of zero.)
      */
-    if (ctx->content_length == 0) {
-        rc = nxt_unit_response_send(ctx->req);
+    if (pctx->content_length == 0) {
+        rc = nxt_unit_response_send(pctx->req);
         if (nxt_slow_path(rc != NXT_UNIT_OK)) {
             return PyErr_Format(PyExc_RuntimeError,
                                 "failed to send response headers");
         }
     }
 
-    Py_INCREF(nxt_py_write_obj);
-    return nxt_py_write_obj;
+    Py_INCREF(pctx->write);
+    return pctx->write;
 }
 
 
 static int
-nxt_python_response_add_field(nxt_python_run_ctx_t *ctx, PyObject *name,
+nxt_python_response_add_field(nxt_python_ctx_t *pctx, PyObject *name,
     PyObject *value, int i)
 {
     int        rc;
@@ -943,20 +989,20 @@ nxt_python_response_add_field(nxt_python_run_ctx_t *ctx, PyObject *name,
         goto fail;
     }
 
-    rc = nxt_unit_response_add_field(ctx->req, name_str, name_length,
+    rc = nxt_unit_response_add_field(pctx->req, name_str, name_length,
                                      value_str, value_length);
     if (nxt_slow_path(rc != NXT_UNIT_OK)) {
         goto fail;
     }
 
-    if (ctx->req->response->fields[i].hash == NXT_UNIT_HASH_CONTENT_LENGTH) {
+    if (pctx->req->response->fields[i].hash == NXT_UNIT_HASH_CONTENT_LENGTH) {
         content_length = nxt_off_t_parse((u_char *) value_str, value_length);
         if (nxt_slow_path(content_length < 0)) {
-            nxt_unit_req_error(ctx->req, "failed to parse Content-Length "
+            nxt_unit_req_error(pctx->req, "failed to parse Content-Length "
                                "value %.*s", (int) value_length, value_str);
 
         } else {
-            ctx->content_length = content_length;
+            pctx->content_length = content_length;
         }
     }
 
@@ -1001,7 +1047,7 @@ nxt_py_write(PyObject *self, PyObject *str)
                             NXT_PYTHON_BYTES_TYPE);
     }
 
-    rc = nxt_python_write(nxt_python_run_ctx, str);
+    rc = nxt_python_write((nxt_python_ctx_t *) self, str);
     if (nxt_slow_path(rc != NXT_UNIT_OK)) {
         return PyErr_Format(PyExc_RuntimeError,
                             "failed to write response value");
@@ -1012,28 +1058,26 @@ nxt_py_write(PyObject *self, PyObject *str)
 
 
 static void
-nxt_py_input_dealloc(nxt_py_input_t *self)
+nxt_py_input_dealloc(nxt_python_ctx_t *self)
 {
     PyObject_Del(self);
 }
 
 
 static PyObject *
-nxt_py_input_read(nxt_py_input_t *self, PyObject *args)
+nxt_py_input_read(nxt_python_ctx_t *pctx, PyObject *args)
 {
-    char                  *buf;
-    PyObject              *content, *obj;
-    Py_ssize_t            size, n;
-    nxt_python_run_ctx_t  *ctx;
+    char        *buf;
+    PyObject    *content, *obj;
+    Py_ssize_t  size, n;
 
-    ctx = nxt_python_run_ctx;
-    if (nxt_slow_path(ctx == NULL)) {
+    if (nxt_slow_path(pctx->req == NULL)) {
         return PyErr_Format(PyExc_RuntimeError,
                             "wsgi.input.read() is called "
                             "outside of WSGI request processing");
     }
 
-    size = ctx->req->content_length;
+    size = pctx->req->content_length;
 
     n = PyTuple_GET_SIZE(args);
 
@@ -1057,8 +1101,8 @@ nxt_py_input_read(nxt_py_input_t *self, PyObject *args)
             }
         }
 
-        if (size == -1 || size > (Py_ssize_t) ctx->req->content_length) {
-            size = ctx->req->content_length;
+        if (size == -1 || size > (Py_ssize_t) pctx->req->content_length) {
+            size = pctx->req->content_length;
         }
     }
 
@@ -1069,22 +1113,20 @@ nxt_py_input_read(nxt_py_input_t *self, PyObject *args)
 
     buf = PyBytes_AS_STRING(content);
 
-    size = nxt_unit_request_read(ctx->req, buf, size);
+    size = nxt_unit_request_read(pctx->req, buf, size);
 
     return content;
 }
 
 
 static PyObject *
-nxt_py_input_readline(nxt_py_input_t *self, PyObject *args)
+nxt_py_input_readline(nxt_python_ctx_t *pctx, PyObject *args)
 {
-    ssize_t               ssize;
-    PyObject              *obj;
-    Py_ssize_t            n;
-    nxt_python_run_ctx_t  *ctx;
+    ssize_t     ssize;
+    PyObject    *obj;
+    Py_ssize_t  n;
 
-    ctx = nxt_python_run_ctx;
-    if (nxt_slow_path(ctx == NULL)) {
+    if (nxt_slow_path(pctx->req == NULL)) {
         return PyErr_Format(PyExc_RuntimeError,
                             "wsgi.input.readline() is called "
                             "outside of WSGI request processing");
@@ -1102,7 +1144,7 @@ nxt_py_input_readline(nxt_py_input_t *self, PyObject *args)
         ssize = PyNumber_AsSsize_t(obj, PyExc_OverflowError);
 
         if (nxt_fast_path(ssize > 0)) {
-            return nxt_py_input_getline(ctx, ssize);
+            return nxt_py_input_getline(pctx, ssize);
         }
 
         if (ssize == 0) {
@@ -1119,18 +1161,18 @@ nxt_py_input_readline(nxt_py_input_t *self, PyObject *args)
         }
     }
 
-    return nxt_py_input_getline(ctx, SSIZE_MAX);
+    return nxt_py_input_getline(pctx, SSIZE_MAX);
 }
 
 
 static PyObject *
-nxt_py_input_getline(nxt_python_run_ctx_t *ctx, size_t size)
+nxt_py_input_getline(nxt_python_ctx_t *pctx, size_t size)
 {
     void      *buf;
     ssize_t   res;
     PyObject  *content;
 
-    res = nxt_unit_request_readline_size(ctx->req, size);
+    res = nxt_unit_request_readline_size(pctx->req, size);
     if (nxt_slow_path(res < 0)) {
         return NULL;
     }
@@ -1146,20 +1188,18 @@ nxt_py_input_getline(nxt_python_run_ctx_t *ctx, size_t size)
 
     buf = PyBytes_AS_STRING(content);
 
-    res = nxt_unit_request_read(ctx->req, buf, res);
+    res = nxt_unit_request_read(pctx->req, buf, res);
 
     return content;
 }
 
 
 static PyObject *
-nxt_py_input_readlines(nxt_py_input_t *self, PyObject *args)
+nxt_py_input_readlines(nxt_python_ctx_t *pctx, PyObject *args)
 {
-    PyObject              *res;
-    nxt_python_run_ctx_t  *ctx;
+    PyObject  *res;
 
-    ctx = nxt_python_run_ctx;
-    if (nxt_slow_path(ctx == NULL)) {
+    if (nxt_slow_path(pctx->req == NULL)) {
         return PyErr_Format(PyExc_RuntimeError,
                             "wsgi.input.readlines() is called "
                             "outside of WSGI request processing");
@@ -1171,7 +1211,7 @@ nxt_py_input_readlines(nxt_py_input_t *self, PyObject *args)
     }
 
     for ( ;; ) {
-        PyObject *line = nxt_py_input_getline(ctx, SSIZE_MAX);
+        PyObject *line = nxt_py_input_getline(pctx, SSIZE_MAX);
         if (nxt_slow_path(line == NULL)) {
             Py_DECREF(res);
             return NULL;
@@ -1201,17 +1241,17 @@ nxt_py_input_iter(PyObject *self)
 static PyObject *
 nxt_py_input_next(PyObject *self)
 {
-    PyObject              *line;
-    nxt_python_run_ctx_t  *ctx;
+    PyObject          *line;
+    nxt_python_ctx_t  *pctx;
 
-    ctx = nxt_python_run_ctx;
-    if (nxt_slow_path(ctx == NULL)) {
+    pctx = (nxt_python_ctx_t *) self;
+    if (nxt_slow_path(pctx->req == NULL)) {
         return PyErr_Format(PyExc_RuntimeError,
                             "wsgi.input.next() is called "
                             "outside of WSGI request processing");
     }
 
-    line = nxt_py_input_getline(ctx, SSIZE_MAX);
+    line = nxt_py_input_getline(pctx, SSIZE_MAX);
     if (nxt_slow_path(line == NULL)) {
         return NULL;
     }
@@ -1227,7 +1267,7 @@ nxt_py_input_next(PyObject *self)
 
 
 static int
-nxt_python_write(nxt_python_run_ctx_t *ctx, PyObject *bytes)
+nxt_python_write(nxt_python_ctx_t *pctx, PyObject *bytes)
 {
     int       rc;
     char      *str_buf;
@@ -1248,16 +1288,16 @@ nxt_python_write(nxt_python_run_ctx_t *ctx, PyObject *bytes)
      * stop iterating over the response when enough data has been sent, or raise
      * an error if the application tries to write() past that point.
      */
-    if (nxt_slow_path(str_length > ctx->content_length - ctx->bytes_sent)) {
-        nxt_unit_req_error(ctx->req, "content length %"PRIu64" exceeded",
-                           ctx->content_length);
+    if (nxt_slow_path(str_length > pctx->content_length - pctx->bytes_sent)) {
+        nxt_unit_req_error(pctx->req, "content length %"PRIu64" exceeded",
+                           pctx->content_length);
 
         return NXT_UNIT_ERROR;
     }
 
-    rc = nxt_unit_response_write(ctx->req, str_buf, str_length);
+    rc = nxt_unit_response_write(pctx->req, str_buf, str_length);
     if (nxt_fast_path(rc == NXT_UNIT_OK)) {
-        ctx->bytes_sent += str_length;
+        pctx->bytes_sent += str_length;
     }
 
     return rc;