Timeout for thread.join()

Question

Is it possible to set a timeout for a call to std::thread::join()? I want to handle the case in which the thread is taking too long to run, or terminate the th

Answer 1

Yes, it is possible. The solution that has been suggested by Galik looks like this:

#include 
#include 
...
// Launch the thread.
std::thread thread(ThreadFnc, ...);
...
// Terminate the thread.
auto future = std::async(std::launch::async, &std::thread::join, &thread);
if (future.wait_for(std::chrono::seconds(5)) 
    == std::future_status::timeout) {

  /* --- Do something, if thread has not terminated within 5 s. --- */

}

However, this essentially launches a third thread that performs the thread.join().

(Note: The destructor of future will block until thread has joined and the auxiliary thread has terminated.)

---

Maybe launching a thread just to bring another thread down is not what you want. There is another, portable solution without an auxiliary thread:

#include 
#include 
...
// Launch the thread.
std::future*  hThread 
  = new std::future(std::async(std::launch::async, ThreadFnc, ...));
...
// Terminate the thread.
if (hThread->wait_for(std::chrono::seconds(5)) 
    == std::future_status::timeout) {

  /* --- Do something, if thread has not terminated within 5 s. --- */

} else
  delete hThread;

where T_return is the return type of your thread procedure. This scenario uses an std::future / std::async combination instead of an std::thread.

Note that hThread is a pointer. When you call the delete operator on it, it will invoke the destructor of *hThread and block until the thread has terminated.

I have tested both versions with gcc 4.9.3 on Cygwin.