txpool

Summary

A persistent process pool in Python for use with Twisted. Provides the ability to run Python callables asynchronously within a pool of persistent processes, as long as the callables, their arguments, and their return values are all picklable.

Installing

pip install txpool

Examples

Here are some simple examples to give you the idea:

    import glob
    from twisted.internet import reactor
    from twisted.internet.defer import inlineCallbacks
    import txpool

    pool = txpool.Pool()

    @inlineCallbacks
    def main():
        result = yield pool.apply_async(glob.glob, ('*.pdf',))
        print result
        reactor.stop()

    reactor.callWhenRunning(main)
    reactor.run()

The callable can instead be specified as a string, using dotted notation to specify the full path to the callable.

    from twisted.internet import reactor
    from twisted.internet.defer import inlineCallbacks
    import txpool

    pool = txpool.Pool()

    @inlineCallbacks
    def main():
        # You can provide an optional timeout (in seconds) for the call
        # (the default is None).
        try:
            result = yield pool.apply_async('glob.glob', ('*.pdf',), timeout=5)
        except txpool.PoolTimeout as e:
            result = e
        print result
        reactor.stop()

    reactor.callWhenRunning(main)
    reactor.run()

The txpool.Pool class can be explicitly sized, asked to log its actions, and/or given a custom name.

    import logging
    from twisted.internet import reactor
    from twisted.internet.defer import inlineCallbacks, gatherResults
    import txpool

    logger = logging.getLogger('example')
    logger.addHandler(logging.StreamHandler())
    logger.setLevel(logging.DEBUG)

    pool = txpool.Pool(size=5, log=logger, name='twisting-by-the-pool')

    @inlineCallbacks
    def main():
        calls = ('math.factorial',) * 5
        args = [(n,) for n in range(150780, 150785)]

        # You can wait until the pool is at full-strength (providing an
        # optional timeout if desired), but it's not required before
        # calling the "apply_async" method.  Jobs are queued until a
        # worker process is available.
        try:
            yield pool.on_ready(timeout=10)
        except txpool.PoolTimeout as e:
            results = e
        else:
            results = yield gatherResults(map(pool.apply_async, calls, args))

        print results

        try:
            # You can gracefully close the pool, which ensures all jobs
            # already queued are completed before shutting down...
            yield pool.close(timeout=10)
        except txpool.PoolTimeout as e:
            print e
            # ...or you can use force and immediately send SIGKILL to each
            # process in the pool.
            yield pool.terminate(timeout=10)

        reactor.stop()

    reactor.callWhenRunning(main)
    reactor.run()