Sub Process in its own Thread

Question

I'm wondering if the following class is sound. I'm using it to launch a bunch of simulators for each test in my test environment.

    class SubProcessInOwnThread(threading.Thread):
        def __init__(self, arguments, currentWorkingDirectory):
            self.arguments = arguments
            self.currentWorkingDirectory = currentWorkingDirectory
            threading.Thread.__init__(self)
            self.isTerminated = False

        def run(self):
            try:
                self.subProcess = subprocess.Popen(self.arguments, cwd=self.currentWorkingDirectory)
                self.subProcess.wait()
            finally:
                self.isTerminated = True

        def kill(self):
            while not self.isTerminated:
                try:
                    self.subProcess.kill()
                except:
                    time.sleep(0.1)

Some senarios:

    # Normal
    subProcessThreadArguments = ["cmd.exe"]
    subProcessThread = SubProcessInOwnThread(subProcessThreadArguments,r"C:\\")
    subProcessThread.start()
    time.sleep(5)
    subProcessThread.kill()

    # Process killed very quickly
    subProcessThreadArguments = ["cmd.exe"]
    subProcessThread = SubProcessInOwnThread(subProcessThreadArguments,r"C:\\")
    subProcessThread.start()
    subProcessThread.kill()

    # Incorrect configuration
    subProcessThreadArguments = ["cmdsfgfg.exe"]
    subProcessThread = SubProcessInOwnThread(subProcessThreadArguments,r"C:\\")
    subProcessThread.start()
    time.sleep(5)
    subProcessThread.kill()

So I can create simulators like this:

    subProcessThreadArguments1 = ["sim1.exe"]
    subProcessThread1 = SubProcessInOwnThread(subProcessThreadArguments1,r"C:\\")
    subProcessThread1.start()

    subProcessThreadArguments2 = ["sim2.exe"]
    subProcessThread2 = SubProcessInOwnThread(subProcessThreadArguments2,r"C:\\")
    subProcessThread2.start()

    # do test...

    subProcessThread1.kill()
    subProcessThread2.kill()

I'd be interested in any improvents. Should I consider the use of the with keyword? If so, what would the benifits be?

Thanks!

glglgl glglgl · Accepted Answer · 2011-09-28T13:42:38

I don't see the point of having a separate thread being stuck in wait() here. Working directly on the subprocess would work like

class SubProcessWithoutThread(object):
    def __init__(self, arguments, currentWorkingDirectory):
        self.arguments = arguments
        self.currentWorkingDirectory = currentWorkingDirectory
        self.isTerminated = False

    def start(self):
        self.subProcess = subprocess.Popen(self.arguments, cwd=self.currentWorkingDirectory)

    def kill(self):
        while self.subProcess.poll() is None:
            try:
                self.subProcess.kill()
            except:
                time.sleep(0.1)

    __enter__ = start
    def __exit__(self, *x):
        self.kill()

(untested)

I have added the methods for a context manager, but I cannot see how that would help you as it would be quite a bunch of with statements which you would have to create, including the necessary indentation.

But maybe I have got your intention wrong...

Sub Process in its own Thread

1 Answers