Does the C++ standard support processes?

Question

I know C++11 added support for threads. For example:

#include <iostream> #include <thread>  void bar() {     std::cout << "bar()\n"; }  int main() {     std::thread thread(bar);     thread.join();      return 0; } 

However, is there a way to execute the bar function in a separate process? If not, is there any discussion on whether such a feature should be added?

Note: I'm aware of the possibility of using platform independent libraries and I'm just curious if C++ supports this directly or will in the future.

Answer 1

No, the c++ standard (particularly C++11) doesn't have any notion of a process (hence I can't give you a more reasonable reference here as a search result from the most popular and currently most up to date c++ documentation site).

I'm also not aware that process support is planned for the next standard version C++-17 (aka C++-1z). At least the Wikipedia Site doesn't mention it.

There is a popular implementation that was proposed for boost, but that never was drawn for a C++ standard proposal.

You usually can't write portable code to run on bare metal systems, where only one process exists.

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However, is there a way to execute the bar() function in a separate process?

The simplest option to do that is to fallback to fork() and wait() as specified by the POSIX Open Group:

#include <iostream> #include <unistd.h> #include <sys/wait.h>  void bar() {     std::cout << "bar()\n"; }      int main(int argc, char **argv) {     pid_t pid = fork();      if (pid == 0)     {         // child process         bar();     }     else if (pid > 0)     {         // parent process         wait(NULL);         }     else     {         // fork failed         std::cerr << "fork() failed!" << std::endl;         return 1;     }       return 0; } 

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Though I don't see much of a point to create an extra process to execute a simple function. Creating a process creates a lot of overhead you don't want in such case.

Well, if you want to start another program using functions from the exec() function family that's a different use case.

I'd recommend sticking to std::threads for your example.