Gearman的Worker的多进程实现

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原创最新推荐文章于 2026-04-23 11:35:48 发布 2.1k 阅读 AI 写同款· GEO 优化 ›

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前言

因为项目原因选择了gearman作为任务委派的中间件，但原生的python拓展包只支持单进程，

期间为了将gearman改造成自适应多进程的方式在实现方式上走进了些误区，

故在此记录这些误区的坑以及目前的最优解决方案。

实现思路

实现方式

主进程接收任务，子进程处理任务。以一个主进程作为任务委派的接收进程，接收到任务后将任务分派给子进程进行处理，处理完成后由该子进程直接返回任务结果给gearman。
多进程接收并处理任务。批量fork多个子进程注册任务，子进程间互不影响，各自完成接收、处理任务的过程。

先说说第一种实现方式的优缺点

优点：

由于worker较多的时间是消耗在等待接收请求上，因此主进程只单一的进行轮训任务接收可以提高单条gearman请求通道的利用率。
由子进程直接返回任务结果可分离主进程与子进程的作业，主进程无需关心任务的结果而只专注于接收任务。

缺点：

主进程接收到任务请求后将请求转发给子进程处理任务，由于子进程处理任务完成后需要将任务结果返回给gearman，因此子进程需要将该任务请求对应的gearman socket传递给子进程，而该过程实现起来过于复杂。（通常具有socket的实例无法通过pickle传递给子进程，虽然Unix的sendmsg可以用来传递socket，但将传递的socket构造成一个GearmanWorker又是另外一件痛苦的事情）
子进程通过传递的socket构造出GearmanWorker后，由于原socket的句柄仍被父进程持有，所以在等待结果的任务请求方无法收到子进程所返回的处理结果。

再来说说第二种实现方式的优缺点

优点：

等价于fork多个原进程，逻辑、作业方式均无改变。
可在fork子进程之前完成公有资源的加载而无需每个GearmanWorker匀加载一次。

缺点：

子进程异常退出后主进程无法正确感知，虽然主进程会维持相同的子进程数，但是异常退出所重启的子进程没有正确注册到gearman接收任务。
主进程异常退出后子进程无法感知，将导致出现僵尸进程。

选择第二种方案，针对缺点的解决办法

利用PID文件记录每个子进程的pid，确保主进程退出后仍能通过PID文件退出子进程。
利用Redis的发布订阅模式实现GearmanWorker的正常退出。

client 端代码： test_multi_gearman_worker.py

#!/usr/bin/env
 python

from gearman import GearmanClient 

gearman_client = GearmanClient(['10.10.13.5:4730']) 

new_jobs = [

    dict(task='test_multi_gearman_worker', data='job-0.mp4'),

    dict(task='test_multi_gearman_worker', data='job-1.mp4'),

    dict(task='test_multi_gearman_worker', data='job-2.mp4'),

    dict(task='test_multi_gearman_worker', data='job-3.mp4'),

    dict(task='test_multi_gearman_worker', data='job-4.mp4'),

    dict(task='test_multi_gearman_worker', data='job-5.mp4'),

    dict(task='test_multi_gearman_worker', data='job-6.mp4'),

    dict(task='test_multi_gearman_worker', data='job-7.mp4'),

    dict(task='test_multi_gearman_worker', data='job-8.mp4'),

    dict(task='test_multi_gearman_worker', data='job-9.mp4'),

    dict(task='test_multi_gearman_worker', data='job-10.mp4'),

]

completed_requests = gearman_client.submit_multiple_jobs(new_jobs)

for current_request in completed_requests:

    print (current_request.result)

print ("Game
 over!")

worker端代码： multi-gearman-worker.py

#!/usr/bin/env
 python

import os

import string

import signal

import threading

import subprocess

import multiprocessing

import redis

from gearman.worker import GearmanWorker, POLL_TIMEOUT_IN_SECONDS

WORKER_PROCESS_PID = '/tmp/multi_gearman_worker.pid'

class MultiGearmanWorker(GearmanWorker):

    """ multi-process gearman worker """

    def __init__(self, host_list=None, redis_host=None, redis_port=None, pid=WORKER_PROCESS_PID):

        super(MultiGearmanWorker, self).__init__(host_list=host_list)

        self.redis_host = redis_host

        self.redis_port = redis_port

        self.pid = pid

    def work(self, poll_timeout=POLL_TIMEOUT_IN_SECONDS, process=multiprocessing.cpu_count()):

        """

        start working, blocking process first

        :param poll_timeout: int , the connection time of gearman

        :param process: int , the number of process for working , the default is the number of cpu-core

        :return:

        """

        print('Clear last
 process.')

        self.gearman_worker_exit()

        print('Ready to
 start %d process for work.' % process)

        gm_poll = multiprocessing.Pool(process)

        for x in range(0, process):

            print('start
 %d child process', x)

            gm_poll.apply_async(gearman_work, (self, poll_timeout, self.pid))

        gm_poll.close()

        gm_poll.join()

        # Delete the PID file if all sub-process exit normally

        if os.path.isfile(self.pid):

            os.remove(self.pid)

        print('Multi gearman
 worker exit.')

    def gearman_worker_exit(self):

        """ Terminate sub-process """

        if not os.path.isfile(self.pid):

            return True

        with open(self.pid, 'r+') as
 f:

            for pid in f.readlines():

                pid = int(pid)

                try:

                    os.kill(pid, signal.SIGKILL)

                    print('Kill
 process %d.' % pid)

                except OSError:

                    print('Process
 %d not exists' % pid)

                    continue

        os.remove(self.pid)

        print('Remove process
 pid file.')

        return True

#The gearman job switch identifier used by the child process

GEARMAN_CONTINUE_WORK = True

def gearman_work(gm_worker, poll_timeout=POLL_TIMEOUT_IN_SECONDS, pid=WORKER_PROCESS_PID):

    """ Open gearman;s worker in multiple processes """

    try:

        """ Record the child process pid, 

             so that the main process is cleared by the supervisor 

        to clear the child process did not exit the last time 

        """

        with open(pid, 'a+') as
 f:

            f.write("%d%s" % (os.getpid(), os.linesep))

        print('Child process
 start for work.')

        continue_working = True

        worker_connections = []

        d = threading.Thread(name='monitor', target=gearman_monitor,

                             args=(gm_worker.redis_host, gm_worker.redis_port))

        d.start()

        def continue_while_connections_alive(any_activity):

            return gm_worker.after_poll(any_activity)

        # Shuffle our connections after the poll timeout

        while continue_working and GEARMAN_CONTINUE_WORK:

            worker_connections = gm_worker.establish_worker_connections()

            continue_working = gm_worker.poll_connections_until_stopped(

                worker_connections, continue_while_connections_alive, timeout=poll_timeout)

        # If we were kicked out of the worker loop, we should shutdown all our connections

        for current_connection in worker_connections:

            current_connection.close()

        print('Gearman worker
 closed')

        return None

    except Exception as e:

        print(e)

def gearman_monitor(redis_host, redis_port):

    """ Listen to dynamic update instructions """

    global GEARMAN_CONTINUE_WORK

    print('Start gearman
 monitor.')

    while GEARMAN_CONTINUE_WORK:

        """To prevent abnormal operation caused by the thread is not monitoring the
 redis response after hanging up, 

       exception handling on here, after an exception re-listen

        """

        try:

            sub = redis.StrictRedis(redis_host, redis_port).pubsub()

            sub.subscribe('hot')

            for i in sub.listen():

                if isinstance(i.get('data'), str):

                    if i.get('data') == 'exit':

                        # worker???????????????????

                        print('Gearman
 monitor receive restart signal.')

                        GEARMAN_CONTINUE_WORK = False

                        sub.unsubscribe('hot')

                        break

                # ????????,?????????gearman
 worker????????

        except Exception as e:

            print(e)

            try:

                sub.unsubscribe('hot')

            except Exception:

                pass

    print('Gearman monitor
 closed')

if __name__ == '__main__':

    def test_multi_gearman_worker(worker, job):

        print('who ', worker) 

        print('do what ', job.data)
        print('Game over!
 ', job.data)

        return job.data

    gearman_worker = MultiGearmanWorker(('10.10.13.5:4730', ), '10.10.13.8', 6379)

    gearman_worker.register_task('test_multi_gearman_worker', test_multi_gearman_worker)

    gearman_worker.work(POLL_TIMEOUT_IN_SECONDS, 5)