Code sample two threads updating
Another possibility is that thread two would first increment When a mutex lock is attempted against a mutex which is held by another thread, the thread is blocked until the mutex is unlocked.
When a thread terminates, the mutex does not unless explicitly unlocked. Man Pages: A join is performed when one wants to wait for a thread to finish.
Normal UNIX processes consist of a single thread of execution that starts in main().
In other words, each line of your code is executed in turn, exactly one line at a time.
Before threads, the normal way to achieve multiple instruction sequences (ie, doing several things at once, in parallel) was to use the fork() and exec() system calls to create several processes -- each being a single thread of execution.
A thread is spawned by defining a function and its arguments which will be processed in the thread.One nice side effect of using these standard mechanisms is that PVM code is fairly portable between UNIX platforms.There are advantages and disadvantages to this method of achieving parallelism.A thread calling routine may launch multiple threads then wait for them to finish to get the results.One waits for the completion of the threads with a join.
Any mutex can be used, there is no explicit link between the mutex and the condition variable. Covers ACE (ADAPTIVE Communication Environment) open-source framework view of threads and other topics.