fix a few rare race conditions that could lead to a lockup

src/switch_core_sqldb.c

@@ -1250,6 +1250,7 @@ struct switch_sql_queue_manager {
 	int thread_running;
 	switch_thread_cond_t *cond;
 	switch_mutex_t *cond_mutex;
+	switch_mutex_t *cond2_mutex;
 	switch_mutex_t *mutex;
 	char *pre_trans_execute;
 	char *post_trans_execute;
@@ -1262,10 +1263,26 @@ struct switch_sql_queue_manager {
 
 static int qm_wake(switch_sql_queue_manager_t *qm)
 {
-	if (switch_mutex_trylock(qm->cond_mutex) == SWITCH_STATUS_SUCCESS) {
+	switch_status_t status;
+	int tries = 0;
+
+ top:
+	
+	status = switch_mutex_trylock(qm->cond_mutex);
+
+	if (status == SWITCH_STATUS_SUCCESS) {
 		switch_thread_cond_signal(qm->cond);
 		switch_mutex_unlock(qm->cond_mutex);
 		return 1;
+	} else {
+		if (switch_mutex_trylock(qm->cond2_mutex) == SWITCH_STATUS_SUCCESS) {
+			switch_mutex_unlock(qm->cond2_mutex);
+		} else {
+			if (++tries < 10) {
+				switch_cond_next();
+				goto top;
+			}
+		}
 	}
 
 	return 0;
@@ -1407,6 +1424,7 @@ SWITCH_DECLARE(switch_status_t) switch_sql_queue_manager_stop(switch_sql_queue_m
 
 	if (qm->thread) {
 		switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_INFO, "%s Stopping SQL thread.\n", qm->name);
+		qm_wake(qm);
 		switch_thread_join(&status, qm->thread);
 		qm->thread = NULL;
 		status = SWITCH_STATUS_SUCCESS;
@@ -1596,6 +1614,7 @@ SWITCH_DECLARE(switch_status_t) switch_sql_queue_manager_init_name(const char *n
 	qm->max_trans = max_trans;
 
 	switch_mutex_init(&qm->cond_mutex, SWITCH_MUTEX_NESTED, qm->pool);
+	switch_mutex_init(&qm->cond2_mutex, SWITCH_MUTEX_NESTED, qm->pool);
 	switch_mutex_init(&qm->mutex, SWITCH_MUTEX_NESTED, qm->pool);
 	switch_thread_cond_create(&qm->cond, qm->pool);
 	
@@ -1850,7 +1869,9 @@ static void *SWITCH_THREAD_FUNC switch_user_sql_thread(switch_thread_t *thread,
 	check:
 
 		if ((lc = qm_ttl(qm)) == 0) {
+			switch_mutex_lock(qm->cond2_mutex);
 			switch_thread_cond_wait(qm->cond, qm->cond_mutex);
+			switch_mutex_unlock(qm->cond2_mutex);
 		}
 
 		i = 40;

src/switch_scheduler.c

@@ -37,6 +37,7 @@ struct switch_scheduler_task_container {
 	int64_t executed;
 	int in_thread;
 	int destroyed;
+	int running;
 	switch_scheduler_func_t func;
 	switch_memory_pool_t *pool;
 	uint32_t flags;
@@ -124,7 +125,11 @@ static int task_thread_loop(int done)
 					tp->in_thread = 1;
 					switch_thread_create(&thread, thd_attr, task_own_thread, tp, tp->pool);
 				} else {
+					tp->running = 1;
+					switch_mutex_unlock(globals.task_mutex);
 					switch_scheduler_execute(tp);
+					switch_mutex_lock(globals.task_mutex);
+					tp->running = 0;
 				}
 			}
 		}
@@ -238,6 +243,13 @@ SWITCH_DECLARE(uint32_t) switch_scheduler_del_task_id(uint32_t task_id)
 								  tp->task.task_id, tp->task.group);
 				break;
 			}
+
+			if (tp->running) {
+				switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_WARNING, "Attempt made to delete running task #%u (group %s)\n",
+								  tp->task.task_id, tp->task.group);
+				break;
+			}
+
 			tp->destroyed++;
 			if (switch_event_create(&event, SWITCH_EVENT_DEL_SCHEDULE) == SWITCH_STATUS_SUCCESS) {
 				switch_event_add_header(event, SWITCH_STACK_BOTTOM, "Task-ID", "%u", tp->task.task_id);