improve thread pool logic

src/include/private/switch_core_pvt.h

@@ -290,10 +290,14 @@ struct switch_session_manager {
 	switch_queue_t *thread_queue;
 	switch_thread_t *manager_thread;
 	switch_mutex_t *mutex;
+	switch_thread_cond_t *cond;
+	switch_mutex_t *cond_mutex;
+	switch_mutex_t *cond2_mutex;
 	int ready;
 	int running;
 	int busy;
 	int popping;
+	int starting;
 };
 
 extern struct switch_session_manager session_manager;

src/switch_core.c

@@ -1792,6 +1792,12 @@ static void switch_load_core_config(const char *file)
 	switch_core_hash_insert(runtime.ptimes, "isac", &d_30);
 	switch_core_hash_insert(runtime.ptimes, "G723", &d_30);
 
+	if (runtime.cpu_count == 1) {
+		switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_WARNING,
+						  "Implicitly setting events-use-dispatch based on a single CPU\n");
+		runtime.events_use_dispatch = 1;
+	}
+
 	if ((xml = switch_xml_open_cfg(file, &cfg, NULL))) {
 		switch_xml_t settings, param;
 

src/switch_core_session.c

@@ -1588,6 +1588,7 @@ static void *SWITCH_THREAD_FUNC switch_core_session_thread_pool_worker(switch_th
 	int check = 0;
 
 	switch_mutex_lock(session_manager.mutex);
+	session_manager.starting--;
 	session_manager.running++;
 	switch_mutex_unlock(session_manager.mutex);
 #ifdef DEBUG_THREAD_POOL
@@ -1682,6 +1683,33 @@ static void thread_launch_failure(void)
 	switch_mutex_unlock(session_manager.mutex);
 }
 
+static int wake_queue(void)
+{
+	switch_status_t status;
+	int tries = 0;
+
+ top:
+	
+	status = switch_mutex_trylock(session_manager.cond_mutex);
+
+	if (status == SWITCH_STATUS_SUCCESS) {
+		switch_thread_cond_signal(session_manager.cond);
+		switch_mutex_unlock(session_manager.cond_mutex);
+		return 1;
+	} else {
+		if (switch_mutex_trylock(session_manager.cond2_mutex) == SWITCH_STATUS_SUCCESS) {
+			switch_mutex_unlock(session_manager.cond2_mutex);
+		} else {
+			if (++tries < 10) {
+				switch_cond_next();
+				goto top;
+			}
+		}
+	}
+
+	return 0;
+}
+
 static switch_status_t check_queue(void) 
 {
 	switch_status_t status = SWITCH_STATUS_FALSE;
@@ -1690,7 +1718,7 @@ static switch_status_t check_queue(void)
 
 	switch_mutex_lock(session_manager.mutex);
 	ttl = switch_queue_size(session_manager.thread_queue);
-	x = (session_manager.running - session_manager.busy);
+	x = ((session_manager.running + session_manager.starting) - session_manager.busy);
 	switch_mutex_unlock(session_manager.mutex);
 
 
@@ -1717,6 +1745,10 @@ static switch_status_t check_queue(void)
 		} else {
 			status = SWITCH_STATUS_SUCCESS;
 		}
+
+		switch_mutex_lock(session_manager.mutex);
+		session_manager.starting++;
+		switch_mutex_unlock(session_manager.mutex);
 		x++;
 	}
 
@@ -1726,12 +1758,20 @@ static switch_status_t check_queue(void)
 
 static void *SWITCH_THREAD_FUNC switch_core_session_thread_pool_manager(switch_thread_t *thread, void *obj)
 {
-	int x = 0;
+
+	uint32_t sleep = 10000000;
+	switch_time_t next = switch_micro_time_now() + sleep;
+
+	switch_mutex_lock(session_manager.cond_mutex);
 
 	while(session_manager.ready) {
-		switch_yield(100000);
+		int check = 1;
 
-		if (++x == 300) {
+		switch_mutex_lock(session_manager.cond2_mutex);
+		switch_thread_cond_timedwait(session_manager.cond, session_manager.cond_mutex, sleep);
+		switch_mutex_unlock(session_manager.cond2_mutex);
+
+		if (switch_micro_time_now() >= next) {
 			if (session_manager.popping) {
 #ifdef DEBUG_THREAD_POOL
 				switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_DEBUG10, 
@@ -1739,17 +1779,20 @@ static void *SWITCH_THREAD_FUNC switch_core_session_thread_pool_manager(switch_t
 #endif
 				switch_queue_interrupt_all(session_manager.thread_queue);
 
-				x--;
-
-				continue;
+				sleep = 100000;
+				check = 0;
 			} else {
-				x = 0;
+				sleep = 10000000;
 			}
 		}
 
-		check_queue();
+		if (check) check_queue();
+
+		next = switch_micro_time_now() + sleep;
 	}
 
+	switch_mutex_unlock(session_manager.cond_mutex);
+
 	while(session_manager.running) {
 		switch_queue_interrupt_all(session_manager.thread_queue);
 		switch_yield(20000);
@@ -1770,7 +1813,7 @@ SWITCH_DECLARE(switch_status_t) switch_thread_pool_launch_thread(switch_thread_d
 	*tdp = NULL;
 
 	switch_queue_push(session_manager.thread_queue, td);
-	check_queue();
+	wake_queue();
 
 	return status;	
 }
@@ -1793,7 +1836,7 @@ SWITCH_DECLARE(switch_status_t) switch_core_session_thread_pool_launch(switch_co
 		td->obj = session;
 		td->func = switch_core_session_thread;
 		switch_queue_push(session_manager.thread_queue, td);
-		check_queue();
+		wake_queue();
 	}
 	switch_mutex_unlock(session->mutex);
 
@@ -2438,6 +2481,9 @@ void switch_core_session_init(switch_memory_pool_t *pool)
 		switch_threadattr_t *thd_attr;
 
 		switch_mutex_init(&session_manager.mutex, SWITCH_MUTEX_NESTED, session_manager.memory_pool);
+		switch_thread_cond_create(&session_manager.cond, session_manager.memory_pool);
+		switch_mutex_init(&session_manager.cond_mutex, SWITCH_MUTEX_NESTED, session_manager.memory_pool);
+		switch_mutex_init(&session_manager.cond2_mutex, SWITCH_MUTEX_NESTED, session_manager.memory_pool);
 		switch_queue_create(&session_manager.thread_queue, 100000, session_manager.memory_pool);
 		switch_threadattr_create(&thd_attr, session_manager.memory_pool);
 		switch_threadattr_stacksize_set(thd_attr, SWITCH_THREAD_STACKSIZE);