打印时无法终止由 Popen 创建的子进程 process.stdout

Question

我创建了一个脚本，它应该运行一个命令并在 15 秒后终止它

import logging

import subprocess
import time
import os
import sys
import signal

#cmd = "ping 192.168.1.1 -t"
cmd = "C:\MyAPP\MyExe.exe -t 80 -I C:\MyApp\Temp -M Documents"

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

**for line in proc.stdout:
    print (line.decode("utf-8"), end='')**

time.sleep(15)
os.kill(proc.pid, signal.SIGTERM)
#proc.kill() #Tried this too but no luck

这不会终止我的子进程。但是，如果我注释掉日志记录到标准输出部分，即

for line in proc.stdout:
    print (line.decode("utf-8"), end='')

子进程已被终止。

我也试过 proc.kill() and CTRL_C_EVENT 但没有成功。任何帮助将不胜感激。请将我视为python

的新手

Answer 1

问题是从 stdout 读取被阻塞。您需要读取子进程的输出或运行单独线程上的计时器。

from subprocess import Popen, PIPE
from threading import Thread
from time import sleep

class ProcKiller(Thread):
    def __init__(self, proc, time_limit):
        super(ProcKiller, self).__init__()
        self.proc = proc
        self.time_limit = time_limit

    def run(self):
        sleep(self.time_limit)
        self.proc.kill()


p = Popen('while true; do echo hi; sleep 1; done', shell=True)
t = ProcKiller(p, 5)
t.start()
p.communicate()

已编辑以反映评论中建议的更改

from subprocess import Popen, PIPE
from threading import Thread
from time import sleep
from signal import SIGTERM
import os

class ProcKiller(Thread):
    def __init__(self, proc, time_limit):
        super(ProcKiller, self).__init__()
        self.proc = proc
        self.time_limit = time_limit

    def run(self):
        sleep(self.time_limit)
        os.kill(self.proc.pid, SIGTERM)

p = Popen('while true; do echo hi; sleep 1; done', shell=True)
t = ProcKiller(p, 5)
t.start()
p.communicate()

Answer 2

在逐行打印其输出的同时在 15 秒内终止子进程：

#!/usr/bin/env python
from __future__ import print_function
from threading import Timer
from subprocess import Popen, PIPE, STDOUT

# start process
cmd = r"C:\MyAPP\MyExe.exe -t 80 -I C:\MyApp\Temp -M Documents"
process = Popen(cmd, stdout=PIPE, stderr=STDOUT,
                bufsize=1, universal_newlines=True)

# terminate process in 15 seconds
timer = Timer(15, terminate, args=[process])
timer.start()

# print output
for line in iter(process.stdout.readline, ''):
    print(line, end='')
process.stdout.close()
process.wait() # wait for the child process to finish
timer.cancel()

注意，这里不需要 shell=True。您可以将 terminate() 定义为：

def terminate(process):
    if process.poll() is None:
        try:
            process.terminate()
        except EnvironmentError:
            pass # ignore

如果你想杀死整个进程树然后定义 terminate() 为：

from subprocess import call

def terminate(process):
    if process.poll() is None:
        call('taskkill /F /T /PID ' + str(process.pid))

对 Windows 路径使用原始字符串文字：r"" 否则你应该转义字符串文字中的所有反斜杠
放弃 shell=True。它在这里无缘无故地创建了一个额外的进程
universal_newlines=True 启用文本模式（在 Python 3 上自动使用区域设置首选编码将字节解码为 Unicode 文本）
iter(process.stdout.readline, '') 是与 Python 2 兼容所必需的（否则由于预读缓冲区错误，数据可能会延迟打印）
使用process.terminate()代替process.send_signal(signal.SIGTERM)或os.kill(proc.pid, signal.SIGTERM)
taskkill 允许在 Windows

打印时无法终止由 Popen 创建的子进程 process.stdout

cannot kill a Sub process created by Popen when printing process.stdout

python

windows

subprocess