Question

我有一个python script.py，它启动子进程并在循环中完成一些工作。这个程序大部分时间在发送SIGUSR2时正确退出，在一些罕见的情况下，我不明白它不会。这是最小的工作示例

import os, subprocess,signal,sys,time

sub = None
shutDown = False

def handler(signum,frame):
    global shutDown, sub

    print("script.py: cached sig: %i " % signum)
    sys.stdout.flush()

    if shutDown:
      print("ignoring signal: %i " % signum)
      return
    else:
      shutDown = True

    if sub is not None and not sub.poll():
        print("script.py: sent signal to doStuff.sh pid: ", sub.pid)
        sys.stdout.flush()
        os.kill(sub.pid, signal.SIGTERM)
        os.waitpid(sub.pid,0)

    sys.exit(128+signum)

signal.signal(signal.SIGINT, handler)
signal.signal(signal.SIGUSR2, handler)
signal.signal(signal.SIGTERM, handler)

for i in range(0,5):
  print("launching %i" % i)
  sub = subprocess.Popen(["./doStuff.sh"], stderr = subprocess.STDOUT)
  sub.wait()

print("finished script.py")

使用doStuff存根

function signalHandler() {
    trap '' SIGINT 
    trap '' SIGTERM
    sleep 10s
    # kill ourself to signal calling process we exited on SIGINT
    trap - SIGINT
    kill -s SIGINT $$
}

trap_with_arg "signalHandler" SIGINT SIGTERM
trap '' SIGUSR2 

echo "doStuff.sh : pid:  $$"
for i in {1..100}; do
    sleep 1s
done

现在启动python script.py并发送两次SIGINT（kill -INT -thePID或按两次Ctrl+C，其中一秒钟：

launching 0
doStuff.sh : pid:  7720
^Cscript.py: cached sig: 2 /** < first time CTRL + C
script.py: sent signal to doStuff.sh pid:  7720 /** < doStuff is waiting now
^Cscript.py: cached sig: 2  /** < second time CTRL + C
ignoring signal: 2          
launching 1                 /** < why continuing loop??? so python 
...

我真的想知道为什么循环继续，因为在处理程序的末尾有一个sys.exit我希望第一次调用shutDownHandler最终应该调用sys.exit。有人看到这个程序有什么缺陷吗？真的很难让它发挥作用。

为什么python没有退出这个信号

0 个答案: