下面是运行任意命令返回其标准输出数据的Python代码,或在非零退出码上引发异常:

proc = subprocess.Popen(
    cmd,
    stderr=subprocess.STDOUT,  # Merge stdout and stderr
    stdout=subprocess.PIPE,
    shell=True)

communication用于等待进程退出:

stdoutdata, stderrdata = proc.communicate()

子进程模块不支持超时——杀死运行超过X秒的进程的能力——因此,通信可能需要很长时间才能运行。

在Windows和Linux上运行的Python程序中实现超时的最简单方法是什么?


当前回答

我对底层细节了解不多;但是,考虑到这一点 python 2.6的API提供了等待线程和的能力 终止进程,那么在一个单独的进程中运行该进程呢 的线程吗?

import subprocess, threading

class Command(object):
    def __init__(self, cmd):
        self.cmd = cmd
        self.process = None

    def run(self, timeout):
        def target():
            print 'Thread started'
            self.process = subprocess.Popen(self.cmd, shell=True)
            self.process.communicate()
            print 'Thread finished'

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

        thread.join(timeout)
        if thread.is_alive():
            print 'Terminating process'
            self.process.terminate()
            thread.join()
        print self.process.returncode

command = Command("echo 'Process started'; sleep 2; echo 'Process finished'")
command.run(timeout=3)
command.run(timeout=1)

这段代码在我的机器中的输出是:

Thread started
Process started
Process finished
Thread finished
0
Thread started
Process started
Terminating process
Thread finished
-15

在哪里可以看到,在第一次执行的过程 正确完成(返回代码0),而在第二个 进程被终止(返回代码-15)。

我没有在windows中测试;但是,除了更新示例之外 命令,我想它应该工作,因为我还没有找到 记录任何说明该线程的内容。Join或process.terminate 不支持。

其他回答

下面是Alex Martelli的解决方案,它是一个具有适当进程终止的模块。其他方法不起作用,因为它们没有使用proc. communication()。所以如果你有一个产生大量输出的进程,它会填满它的输出缓冲区,然后阻塞,直到你从中读取一些东西。

from os import kill
from signal import alarm, signal, SIGALRM, SIGKILL
from subprocess import PIPE, Popen

def run(args, cwd = None, shell = False, kill_tree = True, timeout = -1, env = None):
    '''
    Run a command with a timeout after which it will be forcibly
    killed.
    '''
    class Alarm(Exception):
        pass
    def alarm_handler(signum, frame):
        raise Alarm
    p = Popen(args, shell = shell, cwd = cwd, stdout = PIPE, stderr = PIPE, env = env)
    if timeout != -1:
        signal(SIGALRM, alarm_handler)
        alarm(timeout)
    try:
        stdout, stderr = p.communicate()
        if timeout != -1:
            alarm(0)
    except Alarm:
        pids = [p.pid]
        if kill_tree:
            pids.extend(get_process_children(p.pid))
        for pid in pids:
            # process might have died before getting to this line
            # so wrap to avoid OSError: no such process
            try: 
                kill(pid, SIGKILL)
            except OSError:
                pass
        return -9, '', ''
    return p.returncode, stdout, stderr

def get_process_children(pid):
    p = Popen('ps --no-headers -o pid --ppid %d' % pid, shell = True,
              stdout = PIPE, stderr = PIPE)
    stdout, stderr = p.communicate()
    return [int(p) for p in stdout.split()]

if __name__ == '__main__':
    print run('find /', shell = True, timeout = 3)
    print run('find', shell = True)

我已经在Windows, Linux和Mac上成功地使用了killableprocess。如果你使用Cygwin Python,你将需要OSAF的killableprocess版本,否则本机Windows进程将不会被杀死。

有时需要处理(ffmpeg)而不使用communication(),在这种情况下需要异步超时,这是使用ttldict实现的一种实用方法

PIP安装ttldict

from ttldict import  TTLOrderedDict   
sp_timeout = TTLOrderedDict(default_ttl=10)

def kill_on_timeout(done, proc):
    while True:
        now = time.time()
        if sp_timeout.get('exp_time') == None:
                proc.kill()
                break
    
process = subprocess.Popen(cmd, stdout=subprocess.PIPE, text=True, stderr=subprocess.STDOUT)
            
sp_timeout['exp_time'] = time.time()
            
done = Event()
watcher = Thread(target=kill_on_timeout, args=(done, process))
watcher.daemon = True
watcher.start()
done.set()

for line in process.stdout:
.......

This solution kills the process tree in case of shell=True, passes parameters to the process (or not), has a timeout and gets the stdout, stderr and process output of the call back (it uses psutil for the kill_proc_tree). This was based on several solutions posted in SO including jcollado's. Posting in response to comments by Anson and jradice in jcollado's answer. Tested in Windows Srvr 2012 and Ubuntu 14.04. Please note that for Ubuntu you need to change the parent.children(...) call to parent.get_children(...).

def kill_proc_tree(pid, including_parent=True):
  parent = psutil.Process(pid)
  children = parent.children(recursive=True)
  for child in children:
    child.kill()
  psutil.wait_procs(children, timeout=5)
  if including_parent:
    parent.kill()
    parent.wait(5)

def run_with_timeout(cmd, current_dir, cmd_parms, timeout):
  def target():
    process = subprocess.Popen(cmd, cwd=current_dir, shell=True, stdout=subprocess.PIPE, stdin=subprocess.PIPE, stderr=subprocess.PIPE)

    # wait for the process to terminate
    if (cmd_parms == ""):
      out, err = process.communicate()
    else:
      out, err = process.communicate(cmd_parms)
    errcode = process.returncode

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

  thread.join(timeout)
  if thread.is_alive():
    me = os.getpid()
    kill_proc_tree(me, including_parent=False)
    thread.join()

我已经修改了sussudio的答案。现在函数返回:(returncode, stdout, stderr, timeout) - stdout和stderr被解码为utf-8字符串

def kill_proc(proc, timeout):
  timeout["value"] = True
  proc.kill()

def run(cmd, timeout_sec):
  proc = subprocess.Popen(shlex.split(cmd), stdout=subprocess.PIPE, stderr=subprocess.PIPE)
  timeout = {"value": False}
  timer = Timer(timeout_sec, kill_proc, [proc, timeout])
  timer.start()
  stdout, stderr = proc.communicate()
  timer.cancel()
  return proc.returncode, stdout.decode("utf-8"), stderr.decode("utf-8"), timeout["value"]