std::thread، std::jthread وإدارة المواضيع

#include <iostream>
#include <thread>

void greet(const std::string& name, int times) {
    for (int i = 0; i < times; ++i) {
        std::cout << "Hello, " << name << "! (" << i + 1 << ")\n";
    }
}

int main() {
    // Launch a thread running greet("Alice", 3)
    std::thread t1(greet, "Alice", 3);

    // Lambda-based thread
    std::thread t2([]() {
        std::cout << "Running in a lambda thread\n";
    });

    // MUST join or detach before t1/t2 are destroyed
    t1.join();  // block until t1 finishes
    t2.join();

    std::cout << "All threads finished\n";
    return 0;
}

#include <iostream>
#include <thread>
#include <chrono>

void worker(std::stop_token stoken, int id) {
    while (!stoken.stop_requested()) {
        std::cout << "Worker " << id << " running...\n";
        std::this_thread::sleep_for(std::chrono::milliseconds(200));
    }
    std::cout << "Worker " << id << " stopping gracefully\n";
}

int main() {
    std::jthread jt1(worker, 1);  // stop_token is auto-passed as first arg
    std::jthread jt2(worker, 2);

    std::this_thread::sleep_for(std::chrono::seconds(1));

    // Request both threads to stop
    jt1.request_stop();
    jt2.request_stop();

    // No need to call join() — jthread's destructor does it
    std::cout << "Main thread exiting\n";
    return 0;
}

#include <iostream>
#include <thread>
#include <vector>

thread_local int tls_counter = 0;  // each thread gets its own copy

void count_work(int id) {
    for (int i = 0; i < 1000; ++i) {
        ++tls_counter;  // no data race — each thread has its own
    }
    std::cout << "Thread " << id << ": tls_counter = " << tls_counter << "\n";
}

int main() {
    unsigned int n = std::thread::hardware_concurrency();
    std::cout << "Hardware concurrency: " << n << " threads\n";

    std::vector<std::thread> threads;
    for (unsigned int i = 0; i < n; ++i) {
        threads.emplace_back(count_work, i);
    }
    for (auto& t : threads) {
        t.join();
    }
    // Each thread printed 1000 — they don't share tls_counter
    return 0;
}