Added configurable property to put a cap to task threads (see #2964)

conf/janus.jcfg.sample.in

@@ -117,6 +117,19 @@ general: {
 									# only if allow_loop_indication is set to true;
 									# it's set to false by default to avoid abuses.
 									# Don't change if you don't know what you're doing!
+	#task_pool_size = 100			# By default, while the Janus core is single thread
+									# when it comes to processing incoming messages, it
+									# also uses a task pool with an indefinite amount
+									# of helper threads spawned on demand to handle
+									# messages addressed to plugins. If you want to
+									# limit this task pool size with a maximum number
+									# of concurrent threads, set the 'task_pool_size'
+									# property accordingly: a value of '0' means
+									# 'indefinite' and is the default. Notice that
+									# threads are automatically destroyed when unused
+									# for a while, so whatever value you choose simply
+									# puts a cap on the maximum concurrency.
+									# Don't change if you don't know what you're doing!
 	#opaqueid_in_api = true			# Opaque IDs set by applications are typically
 									# only passed to event handlers for correlation
 									# purposes, but not sent back to the user or

src/janus.c

@@ -4982,6 +4982,14 @@ gint main(int argc, char *argv[]) {
 			loops_api = janus_is_true(item->value);
 		janus_ice_set_static_event_loops(loops, loops_api);
 	}
+	/* Also check if we need a cap on the size of the task pool (default is no limit) */
+	int task_pool_size = -1;
+	item = janus_config_get(config, config_general, janus_config_type_item, "task_pool_size");
+	if(item && item->value) {
+		task_pool_size = atoi(item->value);
+		if(task_pool_size <= 0)
+			task_pool_size = -1;
+	}
 	/* Initialize the ICE stack now */
 	janus_ice_init(ice_lite, ice_tcp, full_trickle, ignore_mdns, ipv6, ipv6_linklocal, rtp_min_port, rtp_max_port);
 	if(janus_ice_set_stun_server(stun_server, stun_port) < 0) {
@@ -5226,7 +5234,7 @@ gint main(int argc, char *argv[]) {
 	}
 	/* Create a thread pool to handle asynchronous requests, no matter what the transport */
 	error = NULL;
-	tasks = g_thread_pool_new(janus_transport_task, NULL, -1, FALSE, &error);
+	tasks = g_thread_pool_new(janus_transport_task, NULL, task_pool_size, FALSE, &error);
 	if(error != NULL) {
 		/* Something went wrong... */
 		JANUS_LOG(LOG_FATAL, "Got error %d (%s) trying to launch the request pool task thread...\n",