为什么把subprocess放在thread里执行？

Question

完整代码在这里：https://github.com/kennethrei...

请看59行的run函数，为什么要在线程里运行subprocess，而不是直接运行？

---

附run函数定义：

def run(self, data, timeout, kill_timeout, env, cwd):
    self.data = data
    environ = dict(os.environ)
    environ.update(env or {})

    def target():

        try:
            self.process = subprocess.Popen(self.cmd,
                universal_newlines=True,
                shell=False,
                env=environ,
                stdin=subprocess.PIPE,
                stdout=subprocess.PIPE,
                stderr=subprocess.PIPE,
                bufsize=0,
                cwd=cwd,
            )

            if sys.version_info[0] >= 3:
                self.out, self.err = self.process.communicate(
                    input = bytes(self.data, "UTF-8") if self.data else None
                )
            else:
                self.out, self.err = self.process.communicate(self.data)
        except Exception as exc:
            self.exc = exc


    thread = threading.Thread(target=target)
    thread.start()

    thread.join(timeout)
    if self.exc:
        raise self.exc
    if _is_alive(thread) :
        _terminate_process(self.process)
        thread.join(kill_timeout)
        if _is_alive(thread):
            _kill_process(self.process)
            thread.join()
    self.returncode = self.process.returncode
    return self.out, self.err

Answer 1

自问自答：
貌似是为了设置timeout...subprocess本身不支持timeout