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;