std::thread::join (3) - Linux Manuals

std::thread::join: std::thread::join

NAME

std::thread::join - std::thread::join

Synopsis

void join(); (since C++11)

Blocks the current thread until the thread identified by *this finishes its execution.
The completion of the thread identified by *this synchronizes with the corresponding successful return from join().
No synchronization is performed on *this itself. Concurrently calling join() on the same std::thread object from multiple threads constitutes a data race that results in undefined behavior.

Parameters

(none)

Return value

(none)

Postconditions

joinable() is false

Exceptions

std::system_error if an error occurs.

Error Conditions

* resource_deadlock_would_occur if this->get_id() == std::this_thread::get_id() (deadlock detected)
* no_such_process if the thread is not valid
* invalid_argument if joinable() is false

Example

// Run this code

  #include <iostream>
  #include <thread>
  #include <chrono>

  void foo()
  {
      // simulate expensive operation
      std::this_thread::sleep_for(std::chrono::seconds(1));
  }

  void bar()
  {
      // simulate expensive operation
      std::this_thread::sleep_for(std::chrono::seconds(1));
  }

  int main()
  {
      std::cout << "starting first helper...\n";
      std::thread helper1(foo);

      std::cout << "starting second helper...\n";
      std::thread helper2(bar);

      std::cout << "waiting for helpers to finish..." << std::endl;
      helper1.join();
      helper2.join();

      std::cout << "done!\n";
  }

Output:

  starting first helper...
  starting second helper...
  waiting for helpers to finish...
  done!

References

* C++11 standard (ISO/IEC 14882:2011):

      * 30.3.1.5 thread members [thread.thread.member]