I just recently wrote an answer to a similar question SO: Eigen library with C++11 multithreading. As I’m interested in this topic too and already had working code at hand, I adapted that sample to OP’s task of matrix multiplication: test-multi-threading-matrix.cc: #include <cassert> #include <cstdint> #include <cstdlib> #include <algorithm> #include <chrono> #include <iomanip> #include <iostream> … Read more
As long as you are using locks to control access to the variable, you do not need volatile on it. In fact, if you’re putting volatile on any variable you’re probably already wrong. https://software.intel.com/en-us/blogs/2007/11/30/volatile-almost-useless-for-multi-threaded-programming/
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
Create a detached thread when you know you won’t want to wait for it with pthread_join(). The only performance benefit is that when a detached thread terminates, its resources can be released immediately instead of having to wait for the thread to be joined before the resources can be released. It is ‘legal’ not to … Read more
pthread.h is a header for the Unix/Linux (POSIX) API for threads. A POSIX layer such as Cygwin would probably compile an app with #include <pthreads.h>. The native Windows threading API is exposed via #include <windows.h> and it works slightly differently to Linux’s threading. Still, there’s a replacement “glue” library maintained at http://sourceware.org/pthreads-win32/ ; note that … Read more
If you are using C++11, here is a right way to do this: Foo& getInst() { static Foo inst(…); return inst; } According to new standard there is no need to care about this problem any more. Object initialization will be made only by one thread, other threads will wait till it complete. Or you … Read more
Well its definately legal in the linux implementation of pthreads, see the notes section in pthreads_exit. It states To allow other threads to continue execution, the main thread should terminate by calling pthread_exit() rather than exit(3). Further, a look at the source code here (torwads the end) shows that it roughly translates to _endthread or … Read more
Initially I come from a posix threads background, and was wondering how does one setup the stack size of the std::thread prior to construction, as I can’t seem to find any references to performing such a task. You can’t. std::thread doesn’t support this because std::thread is standardized, and C++ does not require that a machine … Read more
It sounds like you have two questions here: How can I wait until my thread completes? Answer: This is directly supported by pthreads — make your thread-to-be-stopped JOINABLE (when it is first started), and use pthread_join() to block your current thread until the thread-to-be-stopped is no longer running. How can I tell if my thread … Read more
Building on szx’s answer (so give him the credit), here’s how it would work in your for loop: void *foo(void *i) { int a = *((int *) i); free(i); } int main() { pthread_t thread; for ( int i = 0; i < 10; ++1 ) { int *arg = malloc(sizeof(*arg)); if ( arg == … Read more