std::thread 在 头文件中声明，因此使用 std::thread 时需要包含 头文件。
std::thread 构造
thread() noexcept;
template explicit thread (Fn&& fn, Args&&... args);
thread (const thread&) = delete;
thread (thread&& x) noexcept;
| default (1) | initialization (2) | copy [deleted] (3) | move (4) |
|---|
(1). 默认构造函数，创建一个空的 thread 执行对象。(2). 初始化构造函数，创建一个 thread对象，该 thread对象可被 joinable，新产生的线程会调用 fn 函数，该函数的参数由 args 给出。(3). 拷贝构造函数(被禁用)，意味着 thread 不可被拷贝构造。(4). move 构造函数，move 构造函数，调用成功之后 x 不代表任何 thread 执行对象。
注意：可被 joinable 的 thread 对象必须在他们销毁之前被主线程 join 或者将其设置为 detached.
std::thread 各种构造函数例子如下（参考）：
#include #include #include #include #include #include void f1(int n){ for (int i = 0; i < 5; ++i) { std::cout << "Thread " << n << " executing\n"; std::this_thread::sleep_for(std::chrono::milliseconds(10)); }} void f2(int& n){ for (int i = 0; i < 5; ++i) { std::cout << "Thread 2 executing\n"; ++n; std::this_thread::sleep_for(std::chrono::milliseconds(10)); }} int main(){ int n = 0; std::thread t1; // t1 is not a thread std::thread t2(f1, n + 1); // pass by value std::thread t3(f2, std::ref(n)); // pass by reference std::thread t4(std::move(t3)); // t4 is now running f2(). t3 is no longer a thread t2.join(); t4.join(); std::cout << "Final value of n is " << n << '\n';}
move 赋值操作
thread& operator= (thread&& rhs) noexcept;
thread& operator= (const thread&) = delete;
| move (1) | copy [deleted] (2) |
|---|
(1). move 赋值操作，如果当前对象不可 joinable，需要传递一个右值引用(rhs)给 move 赋值操作；如果当前对象可被 joinable，则 terminate() 报错。(2). 拷贝赋值操作被禁用，thread 对象不可被拷贝。
请看下面的例子：
#include #include #include // std::chrono::seconds#include // std::cout#include // std::thread, std::this_thread::sleep_forvoid thread_task(int n) { std::this_thread::sleep_for(std::chrono::seconds(n)); std::cout << "hello thread " << std::this_thread::get_id() << " paused " << n << " seconds" << std::endl;}/* * === FUNCTION ========================================================= * Name: main * Description: program entry routine. * ======================================================================== */int main(int argc, const char *argv[]){ std::thread threads[5]; std::cout << "Spawning 5 threads...\n"; for (int i = 0; i < 5; i++) { threads[i] = std::thread(thread_task, i + 1); } std::cout << "Done spawning threads! Now wait for them to join\n"; for (auto& t: threads) { t.join(); } std::cout << "All threads joined.\n"; return EXIT_SUCCESS;} /* ---------- end of function main ---------- */
其他成员函数
get_id获取线程 ID。
joinable检查线程是否可被 join。
joinJoin 线程。
detachDetach 线程
swapSwap 线程 。
native_handle返回 native handle。
hardware_concurrency [static]检测硬件并发特性。
