Hi -

From: Daniel Egger <degger@fhm.edu>

Threads are useful if you can find blocking tasks which are parallelisable and thus prevent maximum cpu utilisation. Threads have several drawbacks, one of them are locking issues another one would be overhead for the thread management, another one would be harder debugability, another one would be the against-nature of threads versus processes on Unixsystems.

To that list I would add portability issues. Unless done carefully threading a program causes a program to become less portable. One of the key problems is that of the default 'mutex attribute'. Other systems (Solaris for example, *BSD* systems for another) use 'error checking' mutexes. This difference can make a program almost completely unportable unless care is taken. One method I have seen used to enhance portability is to this logic when initializing mutexes: #ifdef __linux__ pthread_mutexattr_t mu_attr; pthread_mutexattr_t *p_attr = &mu_attr; pthread_mutexattr_settype( &mu_attr, PTHREAD_MUTEX_ERRORCHECK ); #else pthread_mutexattr_t *p_attr = NULL; #endif pthread_mutex_init( &frame_buffer_lock, p_attr );

Please use threads only iff there's some real value in that.

Yes indeed. The paradigm of multiple processes communicating thru a shared memory segment provides many of the advantages of threads and is often easier to debug. Cheers, Steven Schultz sms@2bsd.com