On Thu, Jan 15, 2009 at 10:37 PM, James Mills
<prolo...@shortcircuit.net.au> wrote:
> After some work ... I've taken Laszlo's suggestion of using Value
> (shared memory) objects
> to share state between the -pseudo- Process (manager) object and it's
> underlying multiprocessing.Process
> instance (and subsequent process):
>
> Here is the code:
>
> ----------------------------------------
> #!/usr/bin/env python
>
> import os
> from time import sleep
>
> from threading import activeCount as threads
> from threading import Thread as _Thread
>
> from multiprocessing import Value
> from multiprocessing import Process as _Process
> from multiprocessing import active_children as processes
>
> class Process(object):
>
> def __init__(self, *args, **kwargs):
> super(Process, self).__init__(*args, **kwargs)
>
> self.running = Value("b", False)
> self.thread = _Thread(target=self.run)
> self.process = _Process(target=self._run, args=(self.running,))
>
> def _run(self, running):
> self.thread.start()
>
> try:
> while running.value:
> try:
> sleep(1)
> print "!"
> except SystemExit:
> running.acquire()
> running.value = False
> running.release()
> break
> except KeyboardInterrupt:
> running.acquire()
> running.value = False
> running.release()
> break
> finally:
> running.acquire()
> running.value = False
> running.release()
> self.thread.join()
>
> def start(self):
> self.running.acquire()
> self.running.value = True
> self.running.release()
> self.process.start()
>
> def run(self):
> pass
>
> def stop(self):
> print "%s: Stopping ..." % self
> self.running.acquire()
> self.running.value = False
> self.running.release()
>
> def isAlive(self):
> return self.running.value
>
> class A(Process):
>
> def run(self):
> while self.isAlive():
> sleep(5)
> self.stop()
>
> a = A()
> a.start()
>
> N = 0
>
> while a.isAlive():
> sleep(1)
> print "."
> print "threads: %d" % threads()
> print "processes: %d" % len(processes())
>
> print "DONE"
> ----------------------------------------
>
> Here is the result of running this:
>
> ----------------------------------------
> $ python test3.py
> !
> .
> threads: 1
> processes: 1
> .
> threads: 1
> processes: 1
> !
> !
> .
> threads: 1
> processes: 1
> .
> threads: 1
> processes: 1
> !
> .
> threads: 1
> processes: 1
> !
> <__main__.A object at 0x80de42c>: Stopping ...
> !
> .
> threads: 1
> processes: 0
> DONE
> ----------------------------------------
>
> This appears to work as I intended.
>
> Thoughts / Comments ?
>
> cheers
> James
Personally, rather then using a value to indicate whether to run or
not, I would tend to use an event to coordinate start/stop state.
-jesse
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