Description Often you need to communicate between different threads. In general it's safer not to do this by shared memory, but by explicit message passing. These messages only make sense asynchronously for multi-threaded applications though, as a synchronous operation could as well be done in the same thread. Asynchronous queues are an exception from most other GLib data structures, as they can be used simultaneously from multiple threads without explicit locking and they bring their own builtin reference counting. This is because the nature of an asynchronous queue is that it will always be used by at least 2 concurrent threads. For using an asynchronous queue you first have to create one with g_async_queue_new(). A newly-created queue will get the reference count 1. Whenever another thread is creating a new reference of (that is, pointer to) the queue, it has to increase the reference count (using g_async_queue_ref()). Also, before removing this reference, the reference count has to be decreased (using g_async_queue_unref()). After that the queue might no longer exist so you must not access it after that point. A thread, which wants to send a message to that queue simply calls g_async_queue_push() to push the message to the queue. A thread, which is expecting messages from an asynchronous queue simply calls g_async_queue_pop() for that queue. If no message is available in the queue at that point, the thread is now put to sleep until a message arrives. The message will be removed from the queue and returned. The functions g_async_queue_try_pop() and g_async_queue_timed_pop() can be used to only check for the presence of messages or to only wait a certain time for messages respectively. For almost every function there exist two variants, one that locks the queue and one that doesn't. That way you can hold the queue lock (acquire it with g_async_queue_lock() and release it with g_async_queue_unlock()) over multiple queue accessing instructions. This can be necessary to ensure the integrity of the queue, but should only be used when really necessary, as it can make your life harder if used unwisely. Normally you should only use the locking function variants (those without the suffix _unlocked)