std::thread::join

1	`void` `join();`

(since C++11)

Blocks the current thread until the thread identified by *this finishes its execution.

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

#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]

Links:

http://en.cppreference.com/w/cpp/thread/thread/join

doc_CPP

2025-01-10 15:47:30

Comments

detach	permits the thread to execute independently from the thread handle (public member function)
joinable	checks whether the thread is joinable, i.e. potentially running in parallel context (public member function)