From: Alexander Terekhov (terekhov_at_[hidden])
Date: 2003-10-20 17:46:53
"E. Gladyshev" wrote:
[...]
> If you are interested, we can discuss this condition
> in more details. It is not as straight forward as it might seem.
Real mutexes are designed for memory sharing, not isolation.
"Some have complained that POSIX mutexes don't allow a locking thread
to detect that the previous owner terminated "abnormally"... that's
because it wouldn't do any good to know without isolation between
the entities involved. With IPC mechanisms it makes sense to know,
because you can do something about it."
"Counting semaphores are well matched to dealing with
producer/consumer problems, including those that might exist
between threads of different processes, or between a signal handler
and a thread. In the former case, there may be LITTLE OR NO MEMORY
shared by the processes; in the latter case, one is not
communicating between co-equal threads, but between a thread and an
interrupt-like entity. It is for these reasons that IEEE Std
1003.1-2001 allows semaphores to be used by threads."
regards,
alexander.