std::jthread::joinable
From cppreference.com
bool joinable()constnoexcept; | (since C++20) | |
Checks if the std::jthread object identifies an active thread of execution. Specifically, returns true if get_id()!= std::jthread::id(). So a default constructed jthread is not joinable.
A thread that has finished executing code, but has not yet been joined is still considered an active thread of execution and is therefore joinable.
Contents |
[edit]Parameters
(none)
[edit]Return value
true if the std::jthread object identifies an active thread of execution, false otherwise.
[edit]Example
Run this code
#include <chrono>#include <iostream>#include <thread>usingnamespace std::chrono_literals; void foo(){std::this_thread::sleep_for(500ms);} int main(){std::cout<<std::boolalpha; std::jthread t;std::cout<<"before starting, joinable: "<< t.joinable()<<'\n'; t =std::jthread{foo};std::cout<<"after starting, joinable: "<< t.joinable()<<'\n'; t.join();std::cout<<"after joining, joinable: "<< t.joinable()<<'\n'; t =std::jthread{foo}; t.detach();std::cout<<"after detaching, joinable: "<< t.joinable()<<'\n'; }
Output:
before starting, joinable: false after starting, joinable: true after joining, joinable: false after detaching, joinable: false
[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
| returns the id of the thread (public member function) | |
| waits for the thread to finish its execution (public member function) | |
| permits the thread to execute independently from the thread handle (public member function) |
