diff --git a/auto/configure b/auto/configure
index e8929b8..617d992 100755
--- a/auto/configure
+++ b/auto/configure
@@ -58,6 +58,7 @@
     . auto/unix
 fi
 
+. auto/threads
 . auto/modules
 . auto/lib/conf
 
diff --git a/auto/modules b/auto/modules
index 7885967..5a56957 100644
--- a/auto/modules
+++ b/auto/modules
@@ -432,6 +432,12 @@
 modules="$CORE_MODULES $EVENT_MODULES"
 
 
+# thread pool module should be initialized after events
+if [ $USE_THREADS = YES ]; then
+    modules="$modules $THREAD_POOL_MODULE"
+fi
+
+
 if [ $USE_OPENSSL = YES ]; then
     modules="$modules $OPENSSL_MODULE"
     CORE_DEPS="$CORE_DEPS $OPENSSL_DEPS"
diff --git a/auto/options b/auto/options
index 02affbd..763871f 100644
--- a/auto/options
+++ b/auto/options
@@ -190,6 +190,8 @@
         --without-poll_module)           EVENT_POLL=NONE            ;;
         --with-aio_module)               EVENT_AIO=YES              ;;
 
+        --with-threads)                  USE_THREADS=YES            ;;
+
         --with-file-aio)                 NGX_FILE_AIO=YES           ;;
         --with-ipv6)                     NGX_IPV6=YES               ;;
 
@@ -351,6 +353,8 @@
   --with-poll_module                 enable poll module
   --without-poll_module              disable poll module
 
+  --with-threads                     enable thread pool support
+
   --with-file-aio                    enable file AIO support
   --with-ipv6                        enable IPv6 support
 
diff --git a/auto/sources b/auto/sources
index 1287782..e7f1058 100644
--- a/auto/sources
+++ b/auto/sources
@@ -193,6 +193,13 @@
 
 POSIX_DEPS=src/os/unix/ngx_posix_config.h
 
+THREAD_POOL_MODULE=ngx_thread_pool_module
+THREAD_POOL_DEPS=src/core/ngx_thread_pool.h
+THREAD_POOL_SRCS="src/core/ngx_thread_pool.c
+                  src/os/unix/ngx_thread_cond.c
+                  src/os/unix/ngx_thread_mutex.c
+                  src/os/unix/ngx_thread_id.c"
+
 FREEBSD_DEPS="src/os/unix/ngx_freebsd_config.h src/os/unix/ngx_freebsd.h"
 FREEBSD_SRCS=src/os/unix/ngx_freebsd_init.c
 FREEBSD_SENDFILE_SRCS=src/os/unix/ngx_freebsd_sendfile_chain.c
diff --git a/auto/summary b/auto/summary
index b200906..1be975d 100644
--- a/auto/summary
+++ b/auto/summary
@@ -7,6 +7,10 @@
 echo "Configuration summary"
 
 
+if [ $USE_THREADS = YES ]; then
+    echo "  + using threads"
+fi
+
 if [ $USE_PCRE = DISABLED ]; then
     echo "  + PCRE library is disabled"
 
diff --git a/auto/threads b/auto/threads
new file mode 100644
index 0000000..381f07a
--- /dev/null
+++ b/auto/threads
@@ -0,0 +1,20 @@
+
+# Copyright (C) Nginx, Inc.
+
+
+if [ $USE_THREADS = YES ]; then
+
+    if [ "$NGX_PLATFORM" = win32 ]; then
+        cat << END
+
+$0: --with-threads is not supported on Windows
+
+END
+        exit 1
+    fi
+
+    have=NGX_THREADS . auto/have
+    CORE_DEPS="$CORE_DEPS $THREAD_POOL_DEPS"
+    CORE_SRCS="$CORE_SRCS $THREAD_POOL_SRCS"
+    CORE_LIBS="$CORE_LIBS -lpthread"
+fi
diff --git a/src/core/ngx_core.h b/src/core/ngx_core.h
index aeea0c6..bc1d43f 100644
--- a/src/core/ngx_core.h
+++ b/src/core/ngx_core.h
@@ -22,6 +22,10 @@
 typedef struct ngx_event_aio_s   ngx_event_aio_t;
 typedef struct ngx_connection_s  ngx_connection_t;
 
+#if (NGX_THREADS)
+typedef struct ngx_thread_task_s  ngx_thread_task_t;
+#endif
+
 typedef void (*ngx_event_handler_pt)(ngx_event_t *ev);
 typedef void (*ngx_connection_handler_pt)(ngx_connection_t *c);
 
diff --git a/src/core/ngx_thread_pool.c b/src/core/ngx_thread_pool.c
new file mode 100644
index 0000000..409f86f
--- /dev/null
+++ b/src/core/ngx_thread_pool.c
@@ -0,0 +1,631 @@
+
+/*
+ * Copyright (C) Nginx, Inc.
+ * Copyright (C) Valentin V. Bartenev
+ * Copyright (C) Ruslan Ermilov
+ */
+
+
+#include <ngx_config.h>
+#include <ngx_core.h>
+#include <ngx_thread_pool.h>
+
+
+typedef struct {
+    ngx_array_t               pools;
+} ngx_thread_pool_conf_t;
+
+
+typedef struct {
+    ngx_thread_mutex_t        mtx;
+    ngx_uint_t                count;
+    ngx_thread_task_t        *first;
+    ngx_thread_task_t       **last;
+} ngx_thread_pool_queue_t;
+
+
+struct ngx_thread_pool_s {
+    ngx_thread_cond_t         cond;
+
+    ngx_thread_pool_queue_t   queue;
+
+    ngx_log_t                *log;
+    ngx_pool_t               *pool;
+
+    ngx_str_t                 name;
+    ngx_uint_t                threads;
+    ngx_uint_t                max_queue;
+
+    u_char                   *file;
+    ngx_uint_t                line;
+};
+
+
+static ngx_int_t ngx_thread_pool_init(ngx_thread_pool_t *tp, ngx_log_t *log,
+    ngx_pool_t *pool);
+static ngx_int_t ngx_thread_pool_queue_init(ngx_thread_pool_queue_t *queue,
+    ngx_log_t *log);
+static ngx_int_t ngx_thread_pool_queue_destroy(ngx_thread_pool_queue_t *queue,
+    ngx_log_t *log);
+static void ngx_thread_pool_destroy(ngx_thread_pool_t *tp);
+
+static void *ngx_thread_pool_cycle(void *data);
+static void ngx_thread_pool_handler(ngx_event_t *ev);
+
+static char *ngx_thread_pool(ngx_conf_t *cf, ngx_command_t *cmd, void *conf);
+
+static void *ngx_thread_pool_create_conf(ngx_cycle_t *cycle);
+static char *ngx_thread_pool_init_conf(ngx_cycle_t *cycle, void *conf);
+
+static ngx_int_t ngx_thread_pool_init_worker(ngx_cycle_t *cycle);
+static void ngx_thread_pool_exit_worker(ngx_cycle_t *cycle);
+
+
+static ngx_command_t  ngx_thread_pool_commands[] = {
+
+    { ngx_string("thread_pool"),
+      NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_TAKE23,
+      ngx_thread_pool,
+      0,
+      0,
+      NULL },
+
+      ngx_null_command
+};
+
+
+static ngx_core_module_t  ngx_thread_pool_module_ctx = {
+    ngx_string("thread_pool"),
+    ngx_thread_pool_create_conf,
+    ngx_thread_pool_init_conf
+};
+
+
+ngx_module_t  ngx_thread_pool_module = {
+    NGX_MODULE_V1,
+    &ngx_thread_pool_module_ctx,           /* module context */
+    ngx_thread_pool_commands,              /* module directives */
+    NGX_CORE_MODULE,                       /* module type */
+    NULL,                                  /* init master */
+    NULL,                                  /* init module */
+    ngx_thread_pool_init_worker,           /* init process */
+    NULL,                                  /* init thread */
+    NULL,                                  /* exit thread */
+    ngx_thread_pool_exit_worker,           /* exit process */
+    NULL,                                  /* exit master */
+    NGX_MODULE_V1_PADDING
+};
+
+
+static ngx_str_t  ngx_thread_pool_default = ngx_string("default");
+
+static ngx_uint_t               ngx_thread_pool_task_id;
+static ngx_thread_pool_queue_t  ngx_thread_pool_done;
+
+
+static ngx_int_t
+ngx_thread_pool_init(ngx_thread_pool_t *tp, ngx_log_t *log, ngx_pool_t *pool)
+{
+    int             err;
+    pthread_t       tid;
+    ngx_uint_t      n;
+    pthread_attr_t  attr;
+
+    if (ngx_notify == NULL) {
+        ngx_log_error(NGX_LOG_ALERT, log, 0,
+               "the configured event method cannot be used with thread pools");
+        return NGX_ERROR;
+    }
+
+    if (ngx_thread_pool_queue_init(&tp->queue, log) != NGX_OK) {
+        return NGX_ERROR;
+    }
+
+    if (ngx_thread_cond_create(&tp->cond, log) != NGX_OK) {
+        (void) ngx_thread_pool_queue_destroy(&tp->queue, log);
+        return NGX_ERROR;
+    }
+
+    tp->log = log;
+    tp->pool = pool;
+
+    err = pthread_attr_init(&attr);
+    if (err) {
+        ngx_log_error(NGX_LOG_ALERT, log, err,
+                      "pthread_attr_init() failed");
+        return NGX_ERROR;
+    }
+
+#if 0
+    err = pthread_attr_setstacksize(&attr, PTHREAD_STACK_MIN);
+    if (err) {
+        ngx_log_error(NGX_LOG_ALERT, log, err,
+                      "pthread_attr_setstacksize() failed");
+        return NGX_ERROR;
+    }
+#endif
+
+    for (n = 0; n < tp->threads; n++) {
+        err = pthread_create(&tid, &attr, ngx_thread_pool_cycle, tp);
+        if (err) {
+            ngx_log_error(NGX_LOG_ALERT, log, err,
+                          "pthread_create() failed");
+            return NGX_ERROR;
+        }
+    }
+
+    (void) pthread_attr_destroy(&attr);
+
+    return NGX_OK;
+}
+
+
+static ngx_int_t
+ngx_thread_pool_queue_init(ngx_thread_pool_queue_t *queue, ngx_log_t *log)
+{
+    queue->count = 0;
+    queue->first = NULL;
+    queue->last = &queue->first;
+
+    return ngx_thread_mutex_create(&queue->mtx, log);
+}
+
+
+static ngx_int_t
+ngx_thread_pool_queue_destroy(ngx_thread_pool_queue_t *queue, ngx_log_t *log)
+{
+    return ngx_thread_mutex_destroy(&queue->mtx, log);
+}
+
+
+static void
+ngx_thread_pool_destroy(ngx_thread_pool_t *tp)
+{
+    /* TODO: exit threads */
+
+    (void) ngx_thread_cond_destroy(&tp->cond, tp->log);
+    (void) ngx_thread_pool_queue_destroy(&tp->queue, tp->log);
+}
+
+
+ngx_thread_task_t *
+ngx_thread_task_alloc(ngx_pool_t *pool, size_t size)
+{
+    ngx_thread_task_t  *task;
+
+    task = ngx_pcalloc(pool, sizeof(ngx_thread_task_t) + size);
+    if (task == NULL) {
+        return NULL;
+    }
+
+    task->ctx = task + 1;
+
+    return task;
+}
+
+
+ngx_int_t
+ngx_thread_task_post(ngx_thread_pool_t *tp, ngx_thread_task_t *task)
+{
+    if (task->event.active) {
+        ngx_log_error(NGX_LOG_ALERT, tp->log, 0,
+                      "task #%ui already active", task->id);
+        return NGX_ERROR;
+    }
+
+    if (ngx_thread_mutex_lock(&tp->queue.mtx, tp->log) != NGX_OK) {
+        return NGX_ERROR;
+    }
+
+    if (tp->queue.count >= tp->max_queue) {
+        (void) ngx_thread_mutex_unlock(&tp->queue.mtx, tp->log);
+
+        ngx_log_error(NGX_LOG_ERR, tp->log, 0,
+                      "thread pool \"%V\" queue overflow: %ui tasks waiting",
+                      &tp->name, tp->queue.count);
+        return NGX_ERROR;
+    }
+
+    task->event.active = 1;
+
+    task->id = ngx_thread_pool_task_id++;
+    task->next = NULL;
+
+    if (ngx_thread_cond_signal(&tp->cond, tp->log) != NGX_OK) {
+        (void) ngx_thread_mutex_unlock(&tp->queue.mtx, tp->log);
+        return NGX_ERROR;
+    }
+
+    *tp->queue.last = task;
+    tp->queue.last = &task->next;
+
+    tp->queue.count++;
+
+    (void) ngx_thread_mutex_unlock(&tp->queue.mtx, tp->log);
+
+    ngx_log_debug2(NGX_LOG_DEBUG_CORE, tp->log, 0,
+                   "task #%ui added to thread pool \"%V\"",
+                   task->id, &tp->name);
+
+    return NGX_OK;
+}
+
+
+static void *
+ngx_thread_pool_cycle(void *data)
+{
+    ngx_thread_pool_t *tp = data;
+
+    int                 err;
+    sigset_t            set;
+    ngx_thread_task_t  *task;
+
+#if 0
+    ngx_time_update();
+#endif
+
+    ngx_log_debug1(NGX_LOG_DEBUG_CORE, tp->log, 0,
+                   "thread in pool \"%V\" started", &tp->name);
+
+    sigfillset(&set);
+
+    sigdelset(&set, SIGILL);
+    sigdelset(&set, SIGFPE);
+    sigdelset(&set, SIGSEGV);
+    sigdelset(&set, SIGBUS);
+
+    err = pthread_sigmask(SIG_BLOCK, &set, NULL);
+    if (err) {
+        ngx_log_error(NGX_LOG_ALERT, tp->log, err, "pthread_sigmask() failed");
+        return NULL;
+    }
+
+    for ( ;; ) {
+        if (ngx_thread_mutex_lock(&tp->queue.mtx, tp->log) != NGX_OK) {
+            return NULL;
+        }
+
+        while (tp->queue.count == 0) {
+            if (ngx_thread_cond_wait(&tp->cond, &tp->queue.mtx, tp->log)
+                != NGX_OK)
+            {
+                (void) ngx_thread_mutex_unlock(&tp->queue.mtx, tp->log);
+                return NULL;
+            }
+        }
+
+        tp->queue.count--;
+
+        task = tp->queue.first;
+        tp->queue.first = task->next;
+
+        if (tp->queue.first == NULL) {
+            tp->queue.last = &tp->queue.first;
+        }
+
+        if (ngx_thread_mutex_unlock(&tp->queue.mtx, tp->log) != NGX_OK) {
+            return NULL;
+        }
+
+#if 0
+        ngx_time_update();
+#endif
+
+        ngx_log_debug2(NGX_LOG_DEBUG_CORE, tp->log, 0,
+                       "run task #%ui in thread pool \"%V\"",
+                       task->id, &tp->name);
+
+        task->handler(task->ctx, tp->log);
+
+        ngx_log_debug2(NGX_LOG_DEBUG_CORE, tp->log, 0,
+                       "complete task #%ui in thread pool \"%V\"",
+                       task->id, &tp->name);
+
+        task->next = NULL;
+
+        if (ngx_thread_mutex_lock(&ngx_thread_pool_done.mtx, tp->log)
+            != NGX_OK)
+        {
+            return NULL;
+        }
+
+        *ngx_thread_pool_done.last = task;
+        ngx_thread_pool_done.last = &task->next;
+
+        if (ngx_thread_mutex_unlock(&ngx_thread_pool_done.mtx, tp->log)
+            != NGX_OK)
+        {
+            return NULL;
+        }
+
+        (void) ngx_notify(ngx_thread_pool_handler);
+    }
+}
+
+
+static void
+ngx_thread_pool_handler(ngx_event_t *ev)
+{
+    ngx_event_t        *event;
+    ngx_thread_task_t  *task;
+
+    ngx_log_debug0(NGX_LOG_DEBUG_CORE, ev->log, 0, "thread pool handler");
+
+    if (ngx_thread_mutex_lock(&ngx_thread_pool_done.mtx, ev->log) != NGX_OK) {
+        return;
+    }
+
+    task = ngx_thread_pool_done.first;
+    ngx_thread_pool_done.first = NULL;
+    ngx_thread_pool_done.last = &ngx_thread_pool_done.first;
+
+    if (ngx_thread_mutex_unlock(&ngx_thread_pool_done.mtx, ev->log) != NGX_OK) {
+        return;
+    }
+
+    while (task) {
+        ngx_log_debug1(NGX_LOG_DEBUG_CORE, ev->log, 0,
+                       "run completion handler for task #%ui", task->id);
+
+        event = &task->event;
+        task = task->next;
+
+        event->complete = 1;
+        event->active = 0;
+
+        event->handler(event);
+    }
+}
+
+
+static void *
+ngx_thread_pool_create_conf(ngx_cycle_t *cycle)
+{
+    ngx_thread_pool_conf_t  *tcf;
+
+    tcf = ngx_pcalloc(cycle->pool, sizeof(ngx_thread_pool_conf_t));
+    if (tcf == NULL) {
+        return NULL;
+    }
+
+    if (ngx_array_init(&tcf->pools, cycle->pool, 4,
+                       sizeof(ngx_thread_pool_t *))
+        != NGX_OK)
+    {
+        return NULL;
+    }
+
+    return tcf;
+}
+
+
+static char *
+ngx_thread_pool_init_conf(ngx_cycle_t *cycle, void *conf)
+{
+    ngx_thread_pool_conf_t *tcf = conf;
+
+    ngx_uint_t           i;
+    ngx_thread_pool_t  **tpp;
+
+    tpp = tcf->pools.elts;
+
+    for (i = 0; i < tcf->pools.nelts; i++) {
+
+        if (tpp[i]->threads) {
+            continue;
+        }
+
+        if (tpp[i]->name.len == ngx_thread_pool_default.len
+            && ngx_strncmp(tpp[i]->name.data, ngx_thread_pool_default.data,
+                           ngx_thread_pool_default.len)
+               == 0)
+        {
+            tpp[i]->threads = 32;
+            tpp[i]->max_queue = 65536;
+            continue;
+        }
+
+        ngx_log_error(NGX_LOG_EMERG, cycle->log, 0,
+                      "unknown thread pool \"%V\" in %s:%ui",
+                      &tpp[i]->name, tpp[i]->file, tpp[i]->line);
+
+        return NGX_CONF_ERROR;
+    }
+
+    return NGX_CONF_OK;
+}
+
+
+static char *
+ngx_thread_pool(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
+{
+    ngx_str_t          *value;
+    ngx_uint_t          i;
+    ngx_thread_pool_t  *tp;
+
+    value = cf->args->elts;
+
+    tp = ngx_thread_pool_add(cf, &value[1]);
+
+    if (tp == NULL) {
+        return NGX_CONF_ERROR;
+    }
+
+    if (tp->threads) {
+        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+                           "duplicate thread pool \"%V\"", &tp->name);
+        return NGX_CONF_ERROR;
+    }
+
+    tp->max_queue = 65536;
+
+    for (i = 2; i < cf->args->nelts; i++) {
+
+        if (ngx_strncmp(value[i].data, "threads=", 8) == 0) {
+
+            tp->threads = ngx_atoi(value[i].data + 8, value[i].len - 8);
+
+            if (tp->threads == (ngx_uint_t) NGX_ERROR || tp->threads == 0) {
+                ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+                                   "invalid threads value \"%V\"", &value[i]);
+                return NGX_CONF_ERROR;
+            }
+
+            continue;
+        }
+
+        if (ngx_strncmp(value[i].data, "max_queue=", 10) == 0) {
+
+            tp->max_queue = ngx_atoi(value[i].data + 10, value[i].len - 10);
+
+            if (tp->max_queue == (ngx_uint_t) NGX_ERROR) {
+                ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+                                   "invalid max_queue value \"%V\"", &value[i]);
+                return NGX_CONF_ERROR;
+            }
+
+            continue;
+        }
+    }
+
+    if (tp->threads == 0) {
+        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+                           "\"%V\" must have \"threads\" parameter",
+                           &cmd->name);
+        return NGX_CONF_ERROR;
+    }
+
+    return NGX_CONF_OK;
+}
+
+
+ngx_thread_pool_t *
+ngx_thread_pool_add(ngx_conf_t *cf, ngx_str_t *name)
+{
+    ngx_thread_pool_t       *tp, **tpp;
+    ngx_thread_pool_conf_t  *tcf;
+
+    if (name == NULL) {
+        name = &ngx_thread_pool_default;
+    }
+
+    tp = ngx_thread_pool_get(cf->cycle, name);
+
+    if (tp) {
+        return tp;
+    }
+
+    tp = ngx_pcalloc(cf->pool, sizeof(ngx_thread_pool_t));
+    if (tp == NULL) {
+        return NULL;
+    }
+
+    tp->name = *name;
+    tp->file = cf->conf_file->file.name.data;
+    tp->line = cf->conf_file->line;
+
+    tcf = (ngx_thread_pool_conf_t *) ngx_get_conf(cf->cycle->conf_ctx,
+                                                  ngx_thread_pool_module);
+
+    tpp = ngx_array_push(&tcf->pools);
+    if (tpp == NULL) {
+        return NULL;
+    }
+
+    *tpp = tp;
+
+    return tp;
+}
+
+
+ngx_thread_pool_t *
+ngx_thread_pool_get(ngx_cycle_t *cycle, ngx_str_t *name)
+{
+    ngx_uint_t                i;
+    ngx_thread_pool_t       **tpp;
+    ngx_thread_pool_conf_t   *tcf;
+
+    tcf = (ngx_thread_pool_conf_t *) ngx_get_conf(cycle->conf_ctx,
+                                                  ngx_thread_pool_module);
+
+    tpp = tcf->pools.elts;
+
+    for (i = 0; i < tcf->pools.nelts; i++) {
+
+        if (tpp[i]->name.len == name->len
+            && ngx_strncmp(tpp[i]->name.data, name->data, name->len) == 0)
+        {
+            return tpp[i];
+        }
+    }
+
+    return NULL;
+}
+
+
+static ngx_int_t
+ngx_thread_pool_init_worker(ngx_cycle_t *cycle)
+{
+    ngx_uint_t                i;
+    ngx_thread_pool_t       **tpp;
+    ngx_thread_pool_conf_t   *tcf;
+
+    if (ngx_process != NGX_PROCESS_WORKER
+        && ngx_process != NGX_PROCESS_SINGLE)
+    {
+        return NGX_OK;
+    }
+
+    tcf = (ngx_thread_pool_conf_t *) ngx_get_conf(cycle->conf_ctx,
+                                                  ngx_thread_pool_module);
+
+    if (tcf == NULL) {
+        return NGX_OK;
+    }
+
+    if (ngx_thread_pool_queue_init(&ngx_thread_pool_done, cycle->log)
+        != NGX_OK)
+    {
+        return NGX_ERROR;
+    }
+
+    tpp = tcf->pools.elts;
+
+    for (i = 0; i < tcf->pools.nelts; i++) {
+        if (ngx_thread_pool_init(tpp[i], cycle->log, cycle->pool) != NGX_OK) {
+            return NGX_ERROR;
+        }
+    }
+
+    return NGX_OK;
+}
+
+
+static void
+ngx_thread_pool_exit_worker(ngx_cycle_t *cycle)
+{
+    ngx_uint_t                i;
+    ngx_thread_pool_t       **tpp;
+    ngx_thread_pool_conf_t   *tcf;
+
+    if (ngx_process != NGX_PROCESS_WORKER
+        && ngx_process != NGX_PROCESS_SINGLE)
+    {
+        return;
+    }
+
+    tcf = (ngx_thread_pool_conf_t *) ngx_get_conf(cycle->conf_ctx,
+                                                  ngx_thread_pool_module);
+
+    if (tcf == NULL) {
+        return;
+    }
+
+    tpp = tcf->pools.elts;
+
+    for (i = 0; i < tcf->pools.nelts; i++) {
+        ngx_thread_pool_destroy(tpp[i]);
+    }
+
+    (void) ngx_thread_pool_queue_destroy(&ngx_thread_pool_done, cycle->log);
+}
diff --git a/src/core/ngx_thread_pool.h b/src/core/ngx_thread_pool.h
new file mode 100644
index 0000000..5e5adf6
--- /dev/null
+++ b/src/core/ngx_thread_pool.h
@@ -0,0 +1,36 @@
+
+/*
+ * Copyright (C) Nginx, Inc.
+ * Copyright (C) Valentin V. Bartenev
+ */
+
+
+#ifndef _NGX_THREAD_POOL_H_INCLUDED_
+#define _NGX_THREAD_POOL_H_INCLUDED_
+
+
+#include <ngx_config.h>
+#include <ngx_core.h>
+#include <ngx_event.h>
+
+
+struct ngx_thread_task_s {
+    ngx_thread_task_t   *next;
+    ngx_uint_t           id;
+    void                *ctx;
+    void               (*handler)(void *data, ngx_log_t *log);
+    ngx_event_t          event;
+};
+
+
+typedef struct ngx_thread_pool_s  ngx_thread_pool_t;
+
+
+ngx_thread_pool_t *ngx_thread_pool_add(ngx_conf_t *cf, ngx_str_t *name);
+ngx_thread_pool_t *ngx_thread_pool_get(ngx_cycle_t *cycle, ngx_str_t *name);
+
+ngx_thread_task_t *ngx_thread_task_alloc(ngx_pool_t *pool, size_t size);
+ngx_int_t ngx_thread_task_post(ngx_thread_pool_t *tp, ngx_thread_task_t *task);
+
+
+#endif /* _NGX_THREAD_POOL_H_INCLUDED_ */
diff --git a/src/event/modules/ngx_aio_module.c b/src/event/modules/ngx_aio_module.c
index c881319..5df58d2 100644
--- a/src/event/modules/ngx_aio_module.c
+++ b/src/event/modules/ngx_aio_module.c
@@ -48,6 +48,7 @@
         NULL,                              /* disable an event */
         NULL,                              /* add an connection */
         ngx_aio_del_connection,            /* delete an connection */
+        NULL,                              /* trigger a notify */
         NULL,                              /* process the changes */
         ngx_aio_process_events,            /* process the events */
         ngx_aio_init,                      /* init the events */
diff --git a/src/event/modules/ngx_devpoll_module.c b/src/event/modules/ngx_devpoll_module.c
index 5658e86..f651c9a 100644
--- a/src/event/modules/ngx_devpoll_module.c
+++ b/src/event/modules/ngx_devpoll_module.c
@@ -88,6 +88,7 @@
         ngx_devpoll_del_event,             /* disable an event */
         NULL,                              /* add an connection */
         NULL,                              /* delete an connection */
+        NULL,                              /* trigger a notify */
         NULL,                              /* process the changes */
         ngx_devpoll_process_events,        /* process the events */
         ngx_devpoll_init,                  /* init the events */
diff --git a/src/event/modules/ngx_epoll_module.c b/src/event/modules/ngx_epoll_module.c
index 2674d38..2de265a 100644
--- a/src/event/modules/ngx_epoll_module.c
+++ b/src/event/modules/ngx_epoll_module.c
@@ -164,6 +164,7 @@
         ngx_epoll_del_event,             /* disable an event */
         ngx_epoll_add_connection,        /* add an connection */
         ngx_epoll_del_connection,        /* delete an connection */
+        NULL,                            /* trigger a notify */
         NULL,                            /* process the changes */
         ngx_epoll_process_events,        /* process the events */
         ngx_epoll_init,                  /* init the events */
diff --git a/src/event/modules/ngx_eventport_module.c b/src/event/modules/ngx_eventport_module.c
index b23f3b2..c86c70e 100644
--- a/src/event/modules/ngx_eventport_module.c
+++ b/src/event/modules/ngx_eventport_module.c
@@ -172,6 +172,7 @@
         ngx_eventport_del_event,           /* disable an event */
         NULL,                              /* add an connection */
         NULL,                              /* delete an connection */
+        NULL,                              /* trigger a notify */
         NULL,                              /* process the changes */
         ngx_eventport_process_events,      /* process the events */
         ngx_eventport_init,                /* init the events */
diff --git a/src/event/modules/ngx_iocp_module.c b/src/event/modules/ngx_iocp_module.c
index 75c5a51..2ddf6ea 100644
--- a/src/event/modules/ngx_iocp_module.c
+++ b/src/event/modules/ngx_iocp_module.c
@@ -64,6 +64,7 @@
         NULL,                              /* disable an event */
         NULL,                              /* add an connection */
         ngx_iocp_del_connection,           /* delete an connection */
+        NULL,                              /* trigger a notify */
         NULL,                              /* process the changes */
         ngx_iocp_process_events,           /* process the events */
         ngx_iocp_init,                     /* init the events */
diff --git a/src/event/modules/ngx_kqueue_module.c b/src/event/modules/ngx_kqueue_module.c
index 17214c5..ddcbbad 100644
--- a/src/event/modules/ngx_kqueue_module.c
+++ b/src/event/modules/ngx_kqueue_module.c
@@ -89,6 +89,7 @@
         ngx_kqueue_del_event,              /* disable an event */
         NULL,                              /* add an connection */
         NULL,                              /* delete an connection */
+        NULL,                              /* trigger a notify */
         ngx_kqueue_process_changes,        /* process the changes */
         ngx_kqueue_process_events,         /* process the events */
         ngx_kqueue_init,                   /* init the events */
diff --git a/src/event/modules/ngx_poll_module.c b/src/event/modules/ngx_poll_module.c
index 3617afb..b96c908 100644
--- a/src/event/modules/ngx_poll_module.c
+++ b/src/event/modules/ngx_poll_module.c
@@ -39,6 +39,7 @@
         ngx_poll_del_event,                /* disable an event */
         NULL,                              /* add an connection */
         NULL,                              /* delete an connection */
+        NULL,                              /* trigger a notify */
         NULL,                              /* process the changes */
         ngx_poll_process_events,           /* process the events */
         ngx_poll_init,                     /* init the events */
diff --git a/src/event/modules/ngx_rtsig_module.c b/src/event/modules/ngx_rtsig_module.c
index 9e31afa..3777516 100644
--- a/src/event/modules/ngx_rtsig_module.c
+++ b/src/event/modules/ngx_rtsig_module.c
@@ -130,6 +130,7 @@
         NULL,                            /* disable an event */
         ngx_rtsig_add_connection,        /* add an connection */
         ngx_rtsig_del_connection,        /* delete an connection */
+        NULL,                            /* trigger a notify */
         NULL,                            /* process the changes */
         ngx_rtsig_process_events,        /* process the events */
         ngx_rtsig_init,                  /* init the events */
diff --git a/src/event/modules/ngx_select_module.c b/src/event/modules/ngx_select_module.c
index e837444..a8bf066 100644
--- a/src/event/modules/ngx_select_module.c
+++ b/src/event/modules/ngx_select_module.c
@@ -47,6 +47,7 @@
         ngx_select_del_event,              /* disable an event */
         NULL,                              /* add an connection */
         NULL,                              /* delete an connection */
+        NULL,                              /* trigger a notify */
         NULL,                              /* process the changes */
         ngx_select_process_events,         /* process the events */
         ngx_select_init,                   /* init the events */
diff --git a/src/event/modules/ngx_win32_select_module.c b/src/event/modules/ngx_win32_select_module.c
index be87ded..58b20db 100644
--- a/src/event/modules/ngx_win32_select_module.c
+++ b/src/event/modules/ngx_win32_select_module.c
@@ -48,6 +48,7 @@
         ngx_select_del_event,              /* disable an event */
         NULL,                              /* add an connection */
         NULL,                              /* delete an connection */
+        NULL,                              /* trigger a notify */
         NULL,                              /* process the changes */
         ngx_select_process_events,         /* process the events */
         ngx_select_init,                   /* init the events */
diff --git a/src/event/ngx_event.c b/src/event/ngx_event.c
index 885528a..2a23d50 100644
--- a/src/event/ngx_event.c
+++ b/src/event/ngx_event.c
@@ -178,7 +178,7 @@
     ngx_event_core_create_conf,            /* create configuration */
     ngx_event_core_init_conf,              /* init configuration */
 
-    { NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL }
+    { NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL }
 };
 
 
diff --git a/src/event/ngx_event.h b/src/event/ngx_event.h
index b403204..61ebcb0 100644
--- a/src/event/ngx_event.h
+++ b/src/event/ngx_event.h
@@ -200,6 +200,8 @@
     ngx_int_t  (*add_conn)(ngx_connection_t *c);
     ngx_int_t  (*del_conn)(ngx_connection_t *c, ngx_uint_t flags);
 
+    ngx_int_t  (*notify)(ngx_event_handler_pt handler);
+
     ngx_int_t  (*process_changes)(ngx_cycle_t *cycle, ngx_uint_t nowait);
     ngx_int_t  (*process_events)(ngx_cycle_t *cycle, ngx_msec_t timer,
                    ngx_uint_t flags);
@@ -422,6 +424,8 @@
 #define ngx_add_conn         ngx_event_actions.add_conn
 #define ngx_del_conn         ngx_event_actions.del_conn
 
+#define ngx_notify           ngx_event_actions.notify
+
 #define ngx_add_timer        ngx_event_add_timer
 #define ngx_del_timer        ngx_event_del_timer
 
diff --git a/src/os/unix/ngx_linux_config.h b/src/os/unix/ngx_linux_config.h
index c6c02c9..0c0b168 100644
--- a/src/os/unix/ngx_linux_config.h
+++ b/src/os/unix/ngx_linux_config.h
@@ -93,11 +93,11 @@
 #endif
 
 
-#if (NGX_HAVE_FILE_AIO)
 #if (NGX_HAVE_SYS_EVENTFD_H)
 #include <sys/eventfd.h>
 #endif
 #include <sys/syscall.h>
+#if (NGX_HAVE_FILE_AIO)
 #include <linux/aio_abi.h>
 typedef struct iocb  ngx_aiocb_t;
 #endif
diff --git a/src/os/unix/ngx_thread.h b/src/os/unix/ngx_thread.h
index 2077b3d..9d5f724 100644
--- a/src/os/unix/ngx_thread.h
+++ b/src/os/unix/ngx_thread.h
@@ -111,9 +111,61 @@
 
 #define ngx_thread_volatile
 
+#if (NGX_THREADS)
+
+#include <pthread.h>
+
+
+typedef pthread_mutex_t  ngx_thread_mutex_t;
+
+ngx_int_t ngx_thread_mutex_create(ngx_thread_mutex_t *mtx, ngx_log_t *log);
+ngx_int_t ngx_thread_mutex_destroy(ngx_thread_mutex_t *mtx, ngx_log_t *log);
+ngx_int_t ngx_thread_mutex_lock(ngx_thread_mutex_t *mtx, ngx_log_t *log);
+ngx_int_t ngx_thread_mutex_unlock(ngx_thread_mutex_t *mtx, ngx_log_t *log);
+
+
+typedef pthread_cond_t  ngx_thread_cond_t;
+
+ngx_int_t ngx_thread_cond_create(ngx_thread_cond_t *cond, ngx_log_t *log);
+ngx_int_t ngx_thread_cond_destroy(ngx_thread_cond_t *cond, ngx_log_t *log);
+ngx_int_t ngx_thread_cond_signal(ngx_thread_cond_t *cond, ngx_log_t *log);
+ngx_int_t ngx_thread_cond_wait(ngx_thread_cond_t *cond, ngx_thread_mutex_t *mtx,
+    ngx_log_t *log);
+
+
+#if (NGX_LINUX)
+
+typedef pid_t      ngx_tid_t;
+#define NGX_TID_T_FMT         "%P"
+
+#elif (NGX_FREEBSD)
+
+typedef uint32_t   ngx_tid_t;
+#define NGX_TID_T_FMT         "%uD"
+
+#elif (NGX_DARWIN)
+
+typedef uint64_t   ngx_tid_t;
+#define NGX_TID_T_FMT         "%uA"
+
+#else
+
+typedef uint64_t   ngx_tid_t;
+#define NGX_TID_T_FMT         "%uA"
+
+#endif
+
+ngx_tid_t ngx_thread_tid(void);
+
+#define ngx_log_tid           ngx_thread_tid()
+
+#else
+
 #define ngx_log_tid           0
 #define NGX_TID_T_FMT         "%d"
 
+#endif
+
 #define ngx_mutex_trylock(m)  NGX_OK
 #define ngx_mutex_lock(m)
 #define ngx_mutex_unlock(m)
diff --git a/src/os/unix/ngx_thread_cond.c b/src/os/unix/ngx_thread_cond.c
new file mode 100644
index 0000000..f524696
--- /dev/null
+++ b/src/os/unix/ngx_thread_cond.c
@@ -0,0 +1,87 @@
+
+/*
+ * Copyright (C) Igor Sysoev
+ * Copyright (C) Nginx, Inc.
+ */
+
+
+#include <ngx_config.h>
+#include <ngx_core.h>
+
+
+ngx_int_t
+ngx_thread_cond_create(ngx_thread_cond_t *cond, ngx_log_t *log)
+{
+    ngx_err_t  err;
+
+    err = pthread_cond_init(cond, NULL);
+    if (err == 0) {
+        ngx_log_debug1(NGX_LOG_DEBUG_CORE, log, 0,
+                       "pthread_cond_init(%p)", cond);
+        return NGX_OK;
+    }
+
+    ngx_log_error(NGX_LOG_EMERG, log, err, "pthread_cond_init() failed");
+    return NGX_ERROR;
+}
+
+
+ngx_int_t
+ngx_thread_cond_destroy(ngx_thread_cond_t *cond, ngx_log_t *log)
+{
+    ngx_err_t  err;
+
+    err = pthread_cond_destroy(cond);
+    if (err == 0) {
+        ngx_log_debug1(NGX_LOG_DEBUG_CORE, log, 0,
+                       "pthread_cond_destroy(%p)", cond);
+        return NGX_OK;
+    }
+
+    ngx_log_error(NGX_LOG_EMERG, log, err, "pthread_cond_destroy() failed");
+    return NGX_ERROR;
+}
+
+
+ngx_int_t
+ngx_thread_cond_signal(ngx_thread_cond_t *cond, ngx_log_t *log)
+{
+    ngx_err_t  err;
+
+    err = pthread_cond_signal(cond);
+    if (err == 0) {
+        ngx_log_debug1(NGX_LOG_DEBUG_CORE, log, 0,
+                       "pthread_cond_signal(%p)", cond);
+        return NGX_OK;
+    }
+
+    ngx_log_error(NGX_LOG_EMERG, log, err, "pthread_cond_signal() failed");
+    return NGX_ERROR;
+}
+
+
+ngx_int_t
+ngx_thread_cond_wait(ngx_thread_cond_t *cond, ngx_thread_mutex_t *mtx,
+    ngx_log_t *log)
+{
+    ngx_err_t  err;
+
+    ngx_log_debug1(NGX_LOG_DEBUG_CORE, log, 0,
+                   "pthread_cond_wait(%p) enter", cond);
+
+    err = pthread_cond_wait(cond, mtx);
+
+#if 0
+    ngx_time_update();
+#endif
+
+    if (err == 0) {
+        ngx_log_debug1(NGX_LOG_DEBUG_CORE, log, 0,
+                       "pthread_cond_wait(%p) exit", cond);
+        return NGX_OK;
+    }
+
+    ngx_log_error(NGX_LOG_ALERT, log, err, "pthread_cond_wait() failed");
+
+    return NGX_ERROR;
+}
diff --git a/src/os/unix/ngx_thread_id.c b/src/os/unix/ngx_thread_id.c
new file mode 100644
index 0000000..5174f1a
--- /dev/null
+++ b/src/os/unix/ngx_thread_id.c
@@ -0,0 +1,70 @@
+
+/*
+ * Copyright (C) Igor Sysoev
+ * Copyright (C) Nginx, Inc.
+ */
+
+
+#include <ngx_config.h>
+#include <ngx_core.h>
+#include <ngx_thread_pool.h>
+
+
+#if (NGX_LINUX)
+
+/*
+ * Linux thread id is a pid of thread created by clone(2),
+ * glibc does not provide a wrapper for gettid().
+ */
+
+ngx_tid_t
+ngx_thread_tid(void)
+{
+    return syscall(SYS_gettid);
+}
+
+#elif (NGX_FREEBSD) && (__FreeBSD_version >= 900031)
+
+#include <pthread_np.h>
+
+ngx_tid_t
+ngx_thread_tid(void)
+{
+    return pthread_getthreadid_np();
+}
+
+#elif (NGX_DARWIN)
+
+/*
+ * MacOSX thread has two thread ids:
+ *
+ * 1) MacOSX 10.6 (Snow Leoprad) has pthread_threadid_np() returning
+ *    an uint64_t value, which is obtained using the __thread_selfid()
+ *    syscall.  It is a number above 300,000.
+ */
+
+ngx_tid_t
+ngx_thread_tid(void)
+{
+    uint64_t  tid;
+
+    (void) pthread_threadid_np(NULL, &tid);
+    return tid;
+}
+
+/*
+ * 2) Kernel thread mach_port_t returned by pthread_mach_thread_np().
+ *    It is a number in range 100-100,000.
+ *
+ * return pthread_mach_thread_np(pthread_self());
+ */
+
+#else
+
+ngx_tid_t
+ngx_thread_tid(void)
+{
+    return (uint64_t) (uintptr_t) pthread_self();
+}
+
+#endif
diff --git a/src/os/unix/ngx_thread_mutex.c b/src/os/unix/ngx_thread_mutex.c
new file mode 100644
index 0000000..6e8385e
--- /dev/null
+++ b/src/os/unix/ngx_thread_mutex.c
@@ -0,0 +1,174 @@
+
+/*
+ * Copyright (C) Igor Sysoev
+ * Copyright (C) Nginx, Inc.
+ */
+
+#include <ngx_config.h>
+#include <ngx_core.h>
+
+
+/*
+ * All modern pthread mutex implementations try to acquire a lock
+ * atomically in userland before going to sleep in kernel.  Some
+ * spins before the sleeping.
+ *
+ * In Solaris since version 8 all mutex types spin before sleeping.
+ * The default spin count is 1000.  It can be overridden using
+ * _THREAD_ADAPTIVE_SPIN=100 environment variable.
+ *
+ * In MacOSX all mutex types spin to acquire a lock protecting a mutex's
+ * internals.  If the mutex is busy, thread calls Mach semaphore_wait().
+ *
+ *
+ * PTHREAD_MUTEX_NORMAL lacks deadlock detection and is the fastest
+ * mutex type.
+ *
+ *   Linux:    No spinning.  The internal name PTHREAD_MUTEX_TIMED_NP
+ *             remains from the times when pthread_mutex_timedlock() was
+ *             non-standard extension.  Alias name: PTHREAD_MUTEX_FAST_NP.
+ *   FreeBSD:  No spinning.
+ *
+ *
+ * PTHREAD_MUTEX_ERRORCHECK is usually as fast as PTHREAD_MUTEX_NORMAL
+ * yet has lightweight deadlock detection.
+ *
+ *   Linux:    No spinning.  The internal name: PTHREAD_MUTEX_ERRORCHECK_NP.
+ *   FreeBSD:  No spinning.
+ *
+ *
+ * PTHREAD_MUTEX_RECURSIVE allows recursive locking.
+ *
+ *   Linux:    No spinning.  The internal name: PTHREAD_MUTEX_RECURSIVE_NP.
+ *   FreeBSD:  No spinning.
+ *
+ *
+ * PTHREAD_MUTEX_ADAPTIVE_NP spins on SMP systems before sleeping.
+ *
+ *   Linux:    No deadlock detection.  Dynamically changes a spin count
+ *             for each mutex from 10 to 100 based on spin count taken
+ *             previously.
+ *   FreeBSD:  Deadlock detection.  The default spin count is 2000.
+ *             It can be overriden using LIBPTHREAD_SPINLOOPS environment
+ *             variable or by pthread_mutex_setspinloops_np().  If a lock
+ *             is still busy, sched_yield() can be called on both UP and
+ *             SMP systems.  The default yield loop count is zero, but
+ *             it can be set by LIBPTHREAD_YIELDLOOPS environment
+ *             variable or by pthread_mutex_setyieldloops_np().
+ *   Solaris:  No PTHREAD_MUTEX_ADAPTIVE_NP.
+ *   MacOSX:   No PTHREAD_MUTEX_ADAPTIVE_NP.
+ *
+ *
+ * PTHREAD_MUTEX_ELISION_NP is a Linux extension to elide locks using
+ * Intel Restricted Transactional Memory.  It is the most suitable for
+ * rwlock pattern access because it allows simultaneous reads without lock.
+ * Supported since glibc 2.18.
+ *
+ *
+ * PTHREAD_MUTEX_DEFAULT is default mutex type.
+ *
+ *   Linux:    PTHREAD_MUTEX_NORMAL.
+ *   FreeBSD:  PTHREAD_MUTEX_ERRORCHECK.
+ *   Solaris:  PTHREAD_MUTEX_NORMAL.
+ *   MacOSX:   PTHREAD_MUTEX_NORMAL.
+ */
+
+
+ngx_int_t
+ngx_thread_mutex_create(ngx_thread_mutex_t *mtx, ngx_log_t *log)
+{
+    ngx_err_t            err;
+    pthread_mutexattr_t  attr;
+
+    err = pthread_mutexattr_init(&attr);
+    if (err != 0) {
+        ngx_log_error(NGX_LOG_EMERG, log, err,
+                      "pthread_mutexattr_init() failed");
+        return NGX_ERROR;
+    }
+
+    err = pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_ERRORCHECK);
+    if (err != 0) {
+        ngx_log_error(NGX_LOG_EMERG, log, err,
+                      "pthread_mutexattr_settype"
+                      "(PTHREAD_MUTEX_ERRORCHECK) failed");
+        return NGX_ERROR;
+    }
+
+    err = pthread_mutex_init(mtx, &attr);
+    if (err != 0) {
+        ngx_log_error(NGX_LOG_EMERG, log, err,
+                      "pthread_mutex_init() failed");
+        return NGX_ERROR;
+    }
+
+    err = pthread_mutexattr_destroy(&attr);
+    if (err != 0) {
+        ngx_log_error(NGX_LOG_ALERT, log, err,
+                      "pthread_mutexattr_destroy() failed");
+    }
+
+    ngx_log_debug1(NGX_LOG_DEBUG_CORE, log, 0,
+                   "pthread_mutex_init(%p)", mtx);
+    return NGX_OK;
+}
+
+
+ngx_int_t
+ngx_thread_mutex_destroy(ngx_thread_mutex_t *mtx, ngx_log_t *log)
+{
+    ngx_err_t  err;
+
+    err = pthread_mutex_destroy(mtx);
+    if (err != 0) {
+        ngx_log_error(NGX_LOG_ALERT, log, err,
+                      "pthread_mutex_destroy() failed");
+        return NGX_ERROR;
+    }
+
+    ngx_log_debug1(NGX_LOG_DEBUG_CORE, log, 0,
+                   "pthread_mutex_destroy(%p)", mtx);
+    return NGX_OK;
+}
+
+
+ngx_int_t
+ngx_thread_mutex_lock(ngx_thread_mutex_t *mtx, ngx_log_t *log)
+{
+    ngx_err_t  err;
+
+    ngx_log_debug1(NGX_LOG_DEBUG_CORE, log, 0,
+                   "pthread_mutex_lock(%p) enter", mtx);
+
+    err = pthread_mutex_lock(mtx);
+    if (err == 0) {
+        return NGX_OK;
+    }
+
+    ngx_log_error(NGX_LOG_ALERT, log, err, "pthread_mutex_lock() failed");
+
+    return NGX_ERROR;
+}
+
+
+ngx_int_t
+ngx_thread_mutex_unlock(ngx_thread_mutex_t *mtx, ngx_log_t *log)
+{
+    ngx_err_t  err;
+
+    err = pthread_mutex_unlock(mtx);
+
+#if 0
+    ngx_time_update();
+#endif
+
+    if (err == 0) {
+        ngx_log_debug1(NGX_LOG_DEBUG_CORE, log, 0,
+                       "pthread_mutex_unlock(%p) exit", mtx);
+        return NGX_OK;
+    }
+
+    ngx_log_error(NGX_LOG_ALERT, log, err, "pthread_mutex_unlock() failed");
+
+    return NGX_ERROR;
+}