php - 如何使用 pcntl_waitpid() 返回的 $status？

Question

我正在进行 parent / worker 安排。 parent 将 worker PID 保存在一个数组中，通过以下循环不断检查它们是否仍然存在:

// $workers is an array of PIDs
foreach ($workers as $workerID => $pid) {
    // Check if this worker still exists as a process
    pcntl_waitpid($pid, $status, WNOHANG|WUNTRACED);

    // If the worker exited normally, stop tracking it
    if (pcntl_wifexited($status)) {
        $logger->info("Worker $workerID exited normally");
        array_splice($workers, $workerID, 1); 
    }

    // If it has a session ID, then it's still living
    if (posix_getsid($pid))⋅
        $living[] = $pid;
}

// $dead is the difference between workers we've started
// and those that are still running
$dead = array_diff($workers, $living);

问题是 pcntl_waitpid() 总是将 $status 设置为 0，所以这个循环第一次运行时，父级认为它的所有子级已正常退出，即使它们仍在运行。我是否错误地使用了 pcntl_waitpid()，或者期望它做一些它没有做的事情？

Answer 1

很简单， child 没有退出或停止。您添加了 WNOHANG标志，所以它总是立即返回(它告诉函数不要等待事件)。你应该做的是检查 pcntl_waitpid 的返回值，看看是否返回了任何有值(value)的东西(假设你只想在状态发生变化时运行循环的内容):

foreach ($workers as $workerID => $pid) {
    // Check if this worker still exists as a process
    if (pcntl_waitpid($pid, $status, WNOHANG|WUNTRACED)) {
        // If the worker exited normally, stop tracking it
        if (pcntl_wifexited($status)) {
            $logger->info("Worker $workerID exited normally");
            array_splice($workers, $workerID, 1); 
        }
        // If it has a session ID, then it's still living
        if (posix_getsid($pid))⋅
            $living[] = $pid;
    }
}