Availability:built-in
message_queue_property(?Queue, 
?Property)True if Property is a property of Queue. Defined 
properties are:
- alias(Alias)
- Queue has the given alias name.
- max_size(Size)
- Maximum number of terms that can be in the queue. See
message_queue_create/2. 
This property is not present if there is no limit (default).
- size(Size)
- Queue currently contains Size terms. Note that due to 
concurrent access the returned value may be outdated before it is 
returned. It can be used for debugging purposes as well as work 
distribution purposes.
- waiting(-Count)
- Number of threads waiting for this queue. This property is not present 
if no threads waits for this queue.
The size(Size) property is always present and may be 
used to enumerate the created message queues. Note that this predicate 
does
not enumerate threads, but can be used to query the properties 
of the default queue of a thread.