Gevent学习

Monkey patching

from gevent import monkey monkey.patch_all()

在开头的地方用了patch_all，会把标准库中的thread/socket等给替换掉，变成非阻塞的了.

#!/usr/bin/env python # -*- coding: utf-8 -*- """ # @file py_concurrent_download.py # @brief --------------------------------------------------------- 功能简介 Spawn multiple workers and wait for them to complete --------------------------------------------------------- # @version 1.0.0 # @author LindenTao(lindentao@qq.com) # @date 2017/5/7 16:57 """ from __future__ import print_function import gevent from gevent import monkey # patches stdlib (including socket and ssl modules) to cooperate with other greenlets monkey.patch_all() import sys urls = ['http://www.baidu.com', 'http://www.yandex.ru', 'http://www.qq.com', 'http://www.github.com'] if sys.version_info[0] == 3: from urllib.request import urlopen # pylint:disable=import-error,no-name-in-module else: from urllib2 import urlopen # pylint: disable=import-error def print_head(url): print('Starting %s' % url) data = urlopen(url).read() print('%s: %s bytes: %r' % (url, len(data), data[:50])) jobs = [gevent.spawn(print_head, _url) for _url in urls] gevent.wait(jobs)

用patch_all的结果（异步）： 不用patch_all结果（同步）：

数据结构

事件

import gevent from gevent.event import Event ''' Illustrates the use of events ''' evt = Event() def setter(): '''After 3 seconds, wake all threads waiting on the value of evt''' print('A: Hey wait for me, I have to do something') gevent.sleep(3) print("Ok, I'm done") evt.set() def waiter(): '''After 3 seconds the get call will unblock''' print("I'll wait for you") evt.wait() # blocking print("It's about time") gevent.joinall([ gevent.spawn(setter), gevent.spawn(waiter), gevent.spawn(waiter), gevent.spawn(waiter), gevent.spawn(waiter), gevent.spawn(waiter) ])

应用

简单server

#!/usr/bin/env python2.7 # -*- coding: utf-8 -*- ''' Created on 2016/08/16 File Name:py_gevent.py author: LindenTao Description : python gevent demo ''' # On Unix: Access with ``$ nc 127.0.0.1 5000`` # On Window: Access with ``$ telnet 127.0.0.1 5000`` from gevent.server import StreamServer def handle(socket, address): socket.send("Hello from a telnet!\n") for i in range(5): socket.send(str(i) + '\n') socket.close() server = StreamServer(('127.0.0.1', 5000), handle) server.serve_forever()

WSGI Servers

gevent.wsgi.WSGIServer

from gevent.wsgi import WSGIServer def application(environ, start_response): status = '200 OK' body = '<p>Hello World</p>' headers = [ ('Content-Type', 'text/html') ] start_response(status, headers) return [body] WSGIServer(('', 8000), application).serve_forever()

gevent.pywsgi.WSGIServer

from gevent.pywsgi import WSGIServer def application(environ, start_response): status = '200 OK' headers = [ ('Content-Type', 'text/html') ] start_response(status, headers) yield "<p>Hello" yield "World</p>" WSGIServer(('', 8000), application).serve_forever()

Long Polling

import gevent from gevent.queue import Queue, Empty from gevent.pywsgi import WSGIServer import simplejson as json data_source = Queue() def producer(): while True: data_source.put_nowait('Hello World') gevent.sleep(1) def ajax_endpoint(environ, start_response): status = '200 OK' headers = [ ('Content-Type', 'application/json') ] start_response(status, headers) while True: try: datum = data_source.get(timeout=5) yield json.dumps(datum) + '\n' except Empty: pass gevent.spawn(producer) WSGIServer(('', 8000), ajax_endpoint).serve_forever()

Gevent ZeroMQ

#!/usr/bin/env python2.7 # -*- coding: utf-8 -*- ''' Created on 2016/08/16 File Name:py_gevent.py author: LindenTao Description : python gevent demo ''' # Note: Remember to ``pip install pyzmq gevent_zeromq`` import gevent import zmq.green as zmq # Global Context context = zmq.Context() def server(): server_socket = context.socket(zmq.REQ) server_socket.bind("tcp://127.0.0.1:5000") for request in range(1, 10): server_socket.send("Hello") print('Switched to Server for %s' % request) # Implicit context switch occurs here server_socket.recv() def client(): client_socket = context.socket(zmq.REP) client_socket.connect("tcp://127.0.0.1:5000") for request in range(1, 10): client_socket.recv() print('Switched to Client for %s' % request) # Implicit context switch occurs here client_socket.send("World") publisher = gevent.spawn(server) client = gevent.spawn(client) gevent.joinall([publisher, client])

参考链接

http://xlambda.com/gevent-tutorial/http://www.gevent.org/index.html

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