python - 多进程无法正常退出

Question

我在尝试使用python的多进程时遇到了进程无法正常退出的问题。具体代码如下，环境为python2.7, debian。

# -*-coding:UTF-8 -*-

import multiprocessing as mp
from multiprocessing import Queue
import BeautifulSoup as bs4
from Queue import Empty
import urllib
import json

'''
   getPageData 类似于生产者，获取工作列表。 getDetail 类似消费者，去获取工作的详细信息。queue 中存放工作详情页面的ID
'''

interface = 'http://www.lagou.com/jobs/positionAjax.json?px=default&yx=10k-15k&needAddtionalResult=false'
detailUrl = 'http://www.lagou.com/jobs/{0}.html'


def getPageData(task, queue, keyword='python'):
    while True:
        try:
            page = task.get(timeout=1)
        except Empty:
            break
        post_data = {'kd': keyword, 'pn': page, 'first': 'false'}
        opener = urllib.urlopen(interface, urllib.urlencode(post_data))
        jsonData = json.loads(opener.read())
        results = jsonData['content']['positionResult']['result']
        for result in results:
            queue.put(result['positionId'])


def getDetail(queue, result):
    while True:
        try:
            positionId = queue.get(timeout=1)
        except Empty:
            print mp.current_process().name + 'exit'
            break
        url = detailUrl.format(positionId)
        print url, mp.current_process().name
        opener = urllib.urlopen(url)
        html = opener.read()
        soup = bs4.BeautifulSoup(html)
        content = soup.findAll(attrs={"class": "job_bt"})[0]
        result.put('{0}\n{1}'.format(detailUrl.format(positionId), content))


def start(keyword='python'):
    task = Queue()
    queue = Queue()
    result = Queue()

    post_data = {'kd': keyword, 'pn': 1, 'first': 'true'}
    opener = urllib.urlopen(interface, urllib.urlencode(post_data))
    jsonData = json.loads(opener.read())

    # 页数
    totalCount = jsonData['content']['positionResult']['totalCount']
    resultSize = jsonData['content']['positionResult']['resultSize']
    pageNums = totalCount / resultSize
    if totalCount % resultSize:
        pageNums += 1
    results = jsonData['content']['positionResult']['result']
    for r in results:
        queue.put(r['positionId'])

    # 调试前三页
    pageNums = 3
    for i in range(2, pageNums + 1):
        task.put(i)

    num_consumers = mp.cpu_count()
    processes = [mp.Process(target=getDetail, args=(queue, result))
                 for _ in range(num_consumers)]
    processes.append(mp.Process(target=getPageData, args=(task, queue)))
    for p in processes:
        p.start()
    for p in processes:
        p.join()
    print 'processes over'

    with open('jobs', 'w+') as f:
        while not result.empty():
            a = result.get()
            f.write(a)

if __name__ == '__main__':
    start()

运行结果如下：

# 省略n行...
http://www.lagou.com/jobs/2233028.html Process-3
http://www.lagou.com/jobs/512126.html Process-1
http://www.lagou.com/jobs/2221983.html Process-2
Process-4exit
Process-3exit
Process-1exit
Process-2exit

脚本在此处卡住,无法退出
同样的这个模型我在多线程下运行正常，可以正常退出。
应该不存在死锁....不太清楚多进程下为什么无法正常退出。

尝试使用了线程池的Queue 发现居然好了

# 将result = Queue() 替换
manager = mp.Manager()
result = manager.Queue()

更不明白了

Answer 1

試試

import sys
#退出语句
sys.exit()