并发模型 - python将进程池放在装饰器里为什么不生效也没报错

问题描述

我想把进程池封装在装饰器里，但是它既没生效也没报错

# coding:utf-8import multiprocessingimport tornadofrom tornado.httpclient import AsyncHTTPClientprocess_num = 20 # 进程数url = 'https://www.baidu.com'def handle_request(response): print str(response)def run_in_process(process_num): def _run_in_process(f):def __run_in_process(*args, **kwargs): pool = multiprocessing.Pool(processes=process_num) for i in range(process_num):pool.apply_async(f, args=args, kwds=kwargs, callback=kwargs.get('callback')) pool.close() pool.join()return __run_in_process return _run_in_process@run_in_process(process_num)def main(): http_client = AsyncHTTPClient() http_client.fetch(url, callback=handle_request) global loop loop = tornado.ioloop.IOLoop.instance() if loop._running is False:loop.start()if __name__ == ’__main__’: main()

结果如下

/usr/bin/python2.7 /home/xxx/workspace/py_project/crawler/center/sample.pyProcess finished with exit code 0

但是奇怪的是，我用多进程的方式重写一次，发现是可以生效的

# coding:utf-8import multiprocessingimport tornadofrom tornado.httpclient import AsyncHTTPClientprocess_num = 20 # 进程数url = 'https://www.baidu.com'def handle_request(response): print str(response)def run_in_process(process_num): def _run_in_process(f):def __run_in_process(*args, **kwargs): _processes = [] for i in xrange(process_num):p = multiprocessing.Process(target=f, args=args, kwargs=kwargs)p.start()_processes.append(p) for p in _processes:p.join()return __run_in_process return _run_in_process@run_in_process(process_num)def main(): http_client = AsyncHTTPClient() http_client.fetch(url, callback=handle_request) global loop loop = tornado.ioloop.IOLoop.instance() if loop._running is False:loop.start()if __name__ == ’__main__’: main()

日志如下

/usr/bin/python2.7 /home/shufeng/workspace/private_project/jobscrawler/center/sample.pyHTTPResponse(_body=None,buffer=<_io.BytesIO object at 0x7f2fdaa21ef0>,code=200,effective_url=’http://www.baidu.com’,error=None,headers=<tornado.httputil.HTTPHeaders object at 0x7f2fdaa425d0>,reason=’OK’,request=<tornado.httpclient.HTTPRequest object at 0x7f2fdaa42250>,request_time=0.014312028884887695,time_info={})HTTPResponse(_body=None,buffer=<_io.BytesIO object at 0x7f2fdaa21ef0>,code=200,effective_url=’http://www.baidu.com’,error=None,headers=<tornado.httputil.HTTPHeaders object at 0x7f2fdaa43450>,reason=’OK’,request=<tornado.httpclient.HTTPRequest object at 0x7f2fdaa430d0>,request_time=0.02327895164489746,time_info={})HTTPResponse(_body=None,buffer=<_io.BytesIO object at 0x7f2fdaa21ef0>,code=200,effective_url=’http://www.baidu.com’,error=None,headers=<tornado.httputil.HTTPHeaders object at 0x7f2fdaa43510>,reason=’OK’,request=<tornado.httpclient.HTTPRequest object at 0x7f2fdaa43190>,request_time=0.026951074600219727,time_info={})HTTPResponse(_body=None,buffer=<_io.BytesIO object at 0x7f2fdaa21ef0>,code=200,effective_url=’http://www.baidu.com’,error=None,headers=<tornado.httputil.HTTPHeaders object at 0x7f2fdaa42690>,reason=’OK’,request=<tornado.httpclient.HTTPRequest object at 0x7f2fdaa42310>,request_time=0.0552978515625,time_info={})HTTPResponse(_body=None,buffer=<_io.BytesIO object at 0x7f2fdaa24ef0>,code=200,effective_url=’http://www.baidu.com’,error=None,headers=<tornado.httputil.HTTPHeaders object at 0x7f2fdaa39e10>,reason=’OK’,request=<tornado.httpclient.HTTPRequest object at 0x7f2fdaa39a90>,request_time=0.05612993240356445,time_info={})

同样的情况也会出现在线程池跟协程的使用上，有谁知道这是怎么回事吗？

问题解答

知乎灵剑大神已回答此问题：https://www.zhihu.com/questio...

在linux下运行, 会得到下面的报错:

PicklingError: Can’t pickle <type ’function’>: attribute lookup __builtin__.function failed

而这个报错是因为, 传入不可序列化的对象进进程池时, 报错导致的, 而这个对象就是实例方法, 可以试下用py3运行下, 因为3的实例方法已经可以支持序列化

参考资料: https://virusdefender.net/ind...