Std::thread::join (3) Linux Manual Page

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]

std::thread::join (3) Linux Manual Page