By older versions of the POSIX standard the first method with an initializer is only guaranteed to work with statically allocated variables, not when the variable is an auto variable that is defined in a function body. Although I have never seen a platform where this would not be allowed, even for auto variables, and … Read more
Atomic operations leverage processor support (compare and swap instructions) and don’t use locks at all, whereas locks are more OS-dependent and perform differently on, for example, Win and Linux. Locks actually suspend thread execution, freeing up cpu resources for other tasks, but incurring in obvious context-switching overhead when stopping/restarting the thread. On the contrary, threads … Read more
If you want to run code on many platforms, go for Posix Threads. They are available almost everywhere and are quite mature. On the other hand if you only use Linux/gcc std::thread is perfectly fine – it has a higher abstraction level, a really good interface and plays nicely with other C++11 classes. The C++11 … Read more
The .dll can go in any directory listed in your PATH environment variable. The .lib file can go in any directory listed in your LIB environment variable. The .h files can go in any directory listed in your INCLUDE environment variable. Also see the FAQs page of the link you shared . Read Q6, Q7, … Read more
As highlighted by @R.. in the comments, this appears to be a bug in the implementation of glibc (assuming you are using Linux — I can reproduce this on Linux 2.17 compiled with GCC 4.9.1), in that exit() doesn’t ensure, while flushing and closing streams, there’s no race when it’s called by one thread when … Read more
Pthreads has 3 different kinds of mutexes: Fast mutex, recursive mutex, and error checking mutex. You used a fast mutex which, for performance reasons, will not check for this error. If you use the error checking mutex on Linux you will find you get the results you expect. Below is a small hack of your … Read more
If you send a signal to a process, which thread in the process will handle this signal is undetermined. According to pthread(7): POSIX.1 also requires that threads share a range of other attributes (i.e., these attributes are process-wide rather than per-thread): … – signal dispositions … POSIX.1 distinguishes the notions of signals that are directed … Read more
You need to tell the mutex to be process-shared when it’s inited: http://www.opengroup.org/onlinepubs/007908775/xsh/pthread_mutexattr_setpshared.html Note in particular, “The default value of the attribute is PTHREAD_PROCESS_PRIVATE”, meaning that accessing it from different processes is undefined behaviour.
@paulsm4 I am doubtful about your comment that kernel knows every thing. In this particular context of user level threads, the kernel is unaware of the fact that such a thing is happening. A user level thread’s scheduling is maintained by the user himself (via the interface provided by a library) and the kernel ends … Read more
The POSIX equivalent for what you described is POSIX condition variables. Note that condition variable must always be used in pair with a POSIX mutex, but quite frequently several condition variables use the same mutex, so if you aren’t going to use the mutex exclusively for the condition variable, you shouldn’t place it in the … Read more