std::jthread::join
From cppreference.com
void join(); | (since C++20) | |
Blocks the current thread until the thread identified by *this finishes its execution.
The completion of the thread identified by *thissynchronizes 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.
Contents |
[edit]Parameters
(none)
[edit]Return value
(none)
[edit]Postconditions
joinable() is false.
[edit]Exceptions
std::system_error if an error occurs.
[edit]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.
[edit]Example
Run this code
#include <chrono>#include <iostream>#include <thread> void foo(){// simulate expensive operationstd::this_thread::sleep_for(std::chrono::seconds(1));} void bar(){// simulate expensive operationstd::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";}
Output:
starting first helper... starting second helper... waiting for helpers to finish... done!
[edit]References
- C++23 standard (ISO/IEC 14882:2024):
- 33.4.4.3 Members [thread.jthread.mem]
- C++20 standard (ISO/IEC 14882:2020):
- 32.4.3.2 Members [thread.jthread.mem]
[edit]See also
| permits the thread to execute independently from the thread handle (public member function) | |
| checks whether the thread is joinable, i.e. potentially running in parallel context (public member function) | |
C documentation for thrd_join | |
