python子进程: find out in the signal handler which child terminated

Question

我有一个 python 脚本，它使用 subprocess.Popen 启动多个命令。我添加了一个信号处理程序，如果 child 退出则调用该信号处理程序。我想检查哪个 child 终止了。我可以通过迭代所有子项来做到这一点:

#!/usr/bin/env python
import subprocess
import signal

procs = []

def signal_handler(signum, frame):
    for proc in procs:
        proc.poll()
        if proc.returncode is not None:
            print "%s returned %s" % (proc.pid, proc.returncode)
            procs.remove(proc)

def main():
    signal.signal(signal.SIGCHLD, signal_handler)
    procs.append(subprocess.Popen(["/bin/sleep", "2"]))
    procs.append(subprocess.Popen(["/bin/sleep","5"]))
    # wait so the main process does not terminate immediately
    procs[1].wait()

if __name__ == "__main__":
    main()

我想避免查询所有子流程。有没有办法在信号处理程序中确定哪个子进程终止？

Answer 1

您可以使用 multiprocessing 获得类似的结果。您可以使用 threading如果您不想生成额外的进程，请改为打包。它具有几乎完全相同的界面。基本上，每个子进程调用都发生在一个新进程中，然后启动您的 sleep 进程。

import subprocess
import multiprocessing

def callback(result):
    # do something with result
    pid, returncode = result
    print pid, returncode


def call_process(cmd):
    p = subprocess.Popen(cmd)
    p.wait()
    return p.pid, p.returncode


def main():
    pool = multiprocessing.Pool()
    pool.apply_async(call_process, [["/bin/sleep", "2"]], callback=callback)
    pool.apply_async(call_process, [["/bin/sleep", "5"]], callback=callback)
    pool.close()
    pool.join()


main()