std::jthread:: join

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 jthread 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

#include <chrono>
#include <iostream>
#include <thread>
 
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::jthread helper1(foo);
 
    std::cout << "starting second helper...\n";
    std::jthread helper2(bar);
 
    std::cout << "waiting for helpers to finish..." << std::endl;
    helper1.join();
    helper2.join();
 
    std::cout << "done!\n";
}

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

References

See also