python下multiprocessing和gevent的组合使用

python下multiprocessing和gevent的组合使用

对于有些人来说Gevent和multiprocessing组合在一起使用算是个又高大上又奇葩的工作模式.

Python的多线程受制于GIL全局锁的特性，Gevent身为协程也是线程的一种，只是io调度上自己说了算而已。

那么如何使用多个cpu核心？ 可以利用多进程mutliprocessing来进行多核并行工作，在多进程里面使用gevent协程框架可以更好的做io调度,相比线程来说减少了无谓的上下文切换.

废话少说，直接上个例子.  下面是多进程下生产者消费者的工作模式，代码本身很简单，自己跑一下就知道怎么一回事了.

# blog: xiaorui.cc
 
from multiprocessing import Process, cpu_count, Queue, JoinableQueue
from gevent import monkey;
 
monkey.patch_all();
import gevent
import datetime
from Queue import Empty
 
class Consumer(object):
    def __init__(self, q, no_tasks, name):
        self._no_tasks = no_tasks
        self._queue = q
        self.name = name
        self._rungevent(self._queue, self._no_tasks)
 
    def _rungevent(self, q, no_tasks):
        jobs = [gevent.spawn(self._printq) for x in xrange(no_tasks)]
        gevent.joinall(jobs)
 
    def _printq(self):
        while 1:
            value = self._queue.get()
            if value is None:
                self._queue.task_done()
                break
            else:
                print("{0} time: {1}, value: {2}".format(self.name, \
                                                         datetime.datetime.now(), value))
        return
 
class Producer(object):
    def __init__(self, q, no_tasks, name, consumers_tasks):
        print(name)
        self._q = q
        self._no_tasks = no_tasks
        self.name = name
        self.consumer_tasks = consumers_tasks
        self._rungevent()
 
    def _rungevent(self):
        jobs = [gevent.spawn(self.produce) for x in xrange(self._no_tasks)]
        gevent.joinall(jobs)
        for x in xrange(self.consumer_tasks):
            self._q.put_nowait(None)
        self._q.close()
 
    def produce(self):
        for no in xrange(100):
            print no
            self._q.put(no, block=False)
        return
 
def main():
    total_cores = cpu_count()
    total_processes = total_cores * 2
    q = JoinableQueue()
    print("Gevent on top multiprocessing with 17 gevent coroutines 10 producers gevent and 7 consumers gevent")
    producer_gevents = 10
    consumer_gevents = 7
    jobs = []
    start = datetime.datetime.now()
    for x in xrange(total_processes):
        if not x % 2:
            p = Process(target=Producer, args=(q, producer_gevents, "producer %d" % x, consumer_gevents))
            p.start()
            jobs.append(p)
        else:
            p = Process(target=Consumer, args=(q, consumer_gevents, "consumer %d" % x))
            p.start()
            jobs.append(p)
 
    for job in jobs:
        job.join()
 
    print("{0} process with {1} producer gevents and {2} consumer gevents took{3}\
           seconds to produce {4} numbers and consume".format(total_processes, \
                                                              producer_gevents * total_cores,
                                                              consumer_gevents * total_cores, \
                                                              datetime.datetime.now() - start,
                                                              producer_gevents * total_cores * 100))
 
if __name__ == '__main__':
    main()

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