无法终止Python Popen启动的adb logcat及Logger进程，求解决方法

问题背景 #

以下Python代码可正常拉取安卓设备日志并传入Logger生成目标文本文件，但无法终止两个进程。尝试过terminate()、os.kill(process.pid, signal.SIGKILL)、preexec_fn、os.killpg()等方法后，Logger仍在后台运行。

代码示例 #

def startLogger(logger_dir):
    command0 = 'adb logcat -c'
    command1 = 'adb logcat'
    command2 = 'python3 '+logger_dir+'main.py'

    clear_logcat = subprocess.run(command0.split())
    logcatHandle = subprocess.Popen(command1.split(),stdout=subprocess.PIPE, stderr=subprocess.PIPE, shell=False)
    loggerHandle = subprocess.Popen(command2.split(),stdin=logcatHandle.stdout,shell=False)
    return logcatHandle, loggerHandle

def closeLogger(logcatInstance, loggerInstance):
    loggerInstance.kill() #Killing it first so that it doesn't break the input PIPE
    logcatInstance.kill()
    return logcatInstance, loggerInstance

def main():
    logger_dir = '/Users/Desktop/logger/'
    print("Starting Logger")
    logcatHandle, loggerHandle = startLogger(logger_dir)
    time.sleep(10)
    logcat, logger = closeLogger(logcatHandle, loggerHandle)

main()

排查与解决思路 #

• 子进程脱离父进程控制：你启动的python3 main.py可能创建了独立子进程，仅杀死父进程的话，子进程会被系统进程接管继续运行。可以用ps aux | grep main.py查看进程树，确认是否存在这类情况。
• 管道未正确关闭导致阻塞：杀死loggerHandle后，logcatHandle的stdout管道可能未被关闭，导致adb logcat无法正常退出。创建子进程时添加close_fds=True，确保父进程操作时关闭未使用的文件描述符：

  logcatHandle = subprocess.Popen(
      command1.split(),
      stdout=subprocess.PIPE,
      stderr=subprocess.PIPE,
      shell=False,
      close_fds=True
  )
  loggerHandle = subprocess.Popen(
      command2.split(),
      stdin=logcatHandle.stdout,
      shell=False,
      close_fds=True
  )
  

• 进程组未整体销毁：如果目标进程启动了进程组，单独杀死单个进程无效。创建子进程时设置start_new_session=True，让进程成为新会话领头进程，再用os.killpg杀死整个进程组：
  修改进程创建代码：

  logcatHandle = subprocess.Popen(
      command1.split(),
      stdout=subprocess.PIPE,
      stderr=subprocess.PIPE,
      shell=False,
      start_new_session=True
  )
  loggerHandle = subprocess.Popen(
      command2.split(),
      stdin=logcatHandle.stdout,
      shell=False,
      start_new_session=True
  )
  

  修改关闭逻辑：

  import os
  import signal
  
  def closeLogger(logcatInstance, loggerInstance):
      try:
          os.killpg(os.getpgid(loggerInstance.pid), signal.SIGKILL)
      except ProcessLookupError:
          pass
      try:
          os.killpg(os.getpgid(logcatInstance.pid), signal.SIGKILL)
      except ProcessLookupError:
          pass
      return logcatInstance, loggerInstance
  

• 检查main.py自身退出逻辑：有可能main.py内部存在忽略SIGKILL信号的逻辑，或者处理输入时陷入无限循环（未正确处理EOF）。可以单独运行python3 /Users/Desktop/logger/main.py，手动输入EOF（Ctrl+D）测试是否能正常退出，排查main.py自身问题。

内容的提问来源于stack exchange，提问作者Priyansh Gupta