Since pthreads do not need to be implemented with Linux threads (or kernel threads at all, for that matter), and some implementations are entirely user-level or mixed, the pthreads interface does not provide functions to access these implementation details, as those would not be portable (even across pthreads implementations on Linux). Thread libraries that use … Read more
In C there are some differences however: fork() Purpose is to create a new process, which becomes the child process of the caller Both processes will execute the next instruction following the fork() system call Two identical copies of the computer’s address space,code, and stack are created one for parent and child. Thinking of the … Read more
The process received a SIGPIPE. The default behaviour for this signal is to end the process. A SIGPIPE is sent to a process if it tried to write to a socket that had been shutdown for writing or isn’t connected (anymore). To avoid that the program ends in this case, you could either make the … Read more
The problem was happening when running cmake. Though, in this case cmake was not the problem the error was silent and the -lpthreads related error/warning was the only thing being written to the cmake error log file, although that was not causing any issue. I’ve done a minimal version of the cmakelists.txt and started testing … Read more
There are many text on the subject of condition variables and their usage, so I’ll not bore you with a ton of ugly details. The reason they exist at all is to allow you to notify change in a predicate state. The following are critical in understanding proper use of condition variables and their mutex … Read more
The real reason you should put pthread_cond_wait in a while loop is not because of spurious wakeup. Even if your condition variable did not have spurious wakeup, you would still need the loop to catch a common type of error. Why? Consider what can happen if multiple threads wait on the same condition: Thread 1 … Read more
It is both complicated and differs from Unix to Unix variant. In Linux, for example, a system called Futex (Short for Fast Userspace Mutex) is used. In this system an atomic increment and test operation is performed on the mutex variable in user space. If the result of the operation indicates that there was no … Read more
Will main() catch exceptions thrown from threads? No When a thread throws an exception, it is not caught by main. Is this the standard behavior? Yes, this is standard behaviour. To catch an exception originating in thread X, you have to have the try–catch clause in thread X (for example, around everything in the thread … Read more
The code from Michael Foukarakis is almost good but he initializes the mutex twice which leads to undefined behavior. It should just be: pthread_mutex_t Mutex; pthread_mutexattr_t Attr; pthread_mutexattr_init(&Attr); pthread_mutexattr_settype(&Attr, PTHREAD_MUTEX_RECURSIVE); pthread_mutex_init(&Mutex, &Attr); I actually use this code in production, and I know it works correctly on Linux, Solaris, HP-UX, AIX, Mac OSX and FreeBSD. You … Read more
You can think of greenlets more like cooperative threads. What this means is that there is no scheduler pre-emptively switching between your threads at any given moment – instead your greenlets voluntarily/explicitly give up control to one another at specified points in your code. Does the GIL affect them? Can there be more than one … Read more