std::thread

In C++, multi-threading is supported via the <thread> header. Starting in C++20, std::jthread was introduced to fix lifetime pitfalls in the original std::thread.

The Joinable Destruction Trap

If a standard std::thread object is destroyed while it is still joinable (i.e. it has not been joined or detached, even if it has finished execution), the C++ runtime calls std::terminate immediately.

C++20's std::jthread prevents this by calling join() in its destructor automatically.

Code Walkthrough

Demonstrates the use of standard threads and cooperative stop tokens with C++20 jthreads.

#include <iostream>
#include <thread>
#include <chrono>
void workerTask(std::stop_token stopToken, int id) {
    while (!stopToken.stop_requested()) {
        std::cout << "Worker " << id << " is executing...\n";
        std::this_thread::sleep_for(std::chrono::milliseconds(200));
    }
    std::cout << "Worker " << id << " received stop request and exited.\n";
}
int main() {
    {
        // std::jthread automatically joins on scope exit
        std::jthread jt(workerTask, 1);
        std::this_thread::sleep_for(std::chrono::milliseconds(500));
// Destructor of jt will request stop and join automatically
    }
    std::cout << "jthread scope exited clean.\n";
    return 0;
}

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