This is a reply to Alan Morgan, Paul McGuire and Duncan Booth. I need mutex M because I have other fields in my class that need to be thread-safe.
The reason I want to use a Queue and not a list is that a Queue has additional synchronization besides the mutex. For instance, Queue.get() will block the caller until the queue is non-empty. Of course I could build this behavior on top of a list, but then I'm reinventing the wheel: Queue.Queue is the perfect thing, except for the problem I describe. I can't release my mutex M and then call Queue.get(). That could be a race condition: between the time M is released and Queue's mutex is acquired, another thread could get into my object and mess things up. (We'd need a specific example to see this, and there may be many cases where I could safely release M before calling Queue.get(), but in general it won't work.) -- http://mail.python.org/mailman/listinfo/python-list
