使用 Twisted Python 和 Treq 进行 HTTP 压力测试
jopen
8年前
从事API相关的工作很有挑战性，在高峰期保持系统的稳定及健壮性就是其中之一，这也是我们在Mailgun做很多压力测试的原因。
这么久以来，我们已经尝试了很多种方法，从简单的ApacheBench到复杂些的自定义测试套。但是本贴讲述的，是一种使用python进行“快速粗糙”却非常灵活的压力测试的方法。
使用python写HTTP客户端的时候，我们都很喜欢用
Requests library 。这也是我们向我们的API用户们推荐的。Requests 很强大，但有一个缺点，它是一个模块化的每线程一个调用的东西，很难或者说不可能用它来快速的产生成千上万级别的请求。
Treq on Twisted简介
为解决这个问题我们引入了Treq ( Github库 )。Treq是一个HTTP客户端库，受Requests影响，但是它运行在Twisted上，具有Twisted典型的强大能力：处理网络I/O时它是异步且高度并发的方式。
Treq并不仅仅限于压力测试：它是写高并发HTTP客户端的好工具，比如网页抓取。Treq很优雅、易于使用且强大。这是一个例子：
>>> from treq import get >>> def done(response): ... print response.code ... reactor.stop() >>> get("http://www.github.com").addCallback(done) >>> from twisted.internet import reactor >>> reactor.run() 200>>> fromtreqimportget >>> defdone(response): ... printresponse.code ... reactor.stop() >>> get("http://www.github.com").addCallback(done) >>> fromtwisted.internetimportreactor >>> reactor.run() 200简单的测试脚本
如下是一个使用Treq的简单脚本，用最大可能量的请求来对单一URL进行轰炸。
#!/usr/bin/env python from twisted.internet import epollreactor epollreactor.install() from twisted.internet import reactor, task from twisted.web.client import HTTPConnectionPool import treq import random from datetime import datetime req_generated = 0 req_made = 0 req_done = 0 cooperator = task.Cooperator() pool = HTTPConnectionPool(reactor) def counter(): '''This function gets called once a second and prints the progress at one second intervals. ''' print("Requests: {} generated; {} made; {} done".format( req_generated, req_made, req_done)) # reset the counters and reschedule ourselves req_generated = req_made = req_done = 0 reactor.callLater(1, counter) def body_received(body): global req_done req_done += 1 def request_done(response): global req_made deferred = treq.json_content(response) req_made += 1 deferred.addCallback(body_received) deferred.addErrback(lambda x: None) # ignore errors return deferred def request(): deferred = treq.post('http://api.host/v2/loadtest/messages', auth=('api', 'api-key'), data={'from': 'Loadtest <test@example.com>', 'to': 'to@example.org', 'subject': "test"}, pool=pool) deferred.addCallback(request_done) return deferred def requests_generator(): global req_generated while True: deferred = request() req_generated += 1 # do not yield deferred here so cooperator won't pause until # response is received yield None if __name__ == '__main__': # make cooperator work on spawning requests cooperator.cooperate(requests_generator()) # run the counter that will be reporting sending speed once a second reactor.callLater(1, counter) # run the reactor reactor.run()#!/usr/bin/env python fromtwisted.internetimportepollreactor epollreactor.install() fromtwisted.internetimportreactor, task fromtwisted.web.clientimportHTTPConnectionPool importtreq importrandom fromdatetimeimportdatetime req_generated = 0 req_made = 0 req_done = 0 cooperator = task.Cooperator() pool = HTTPConnectionPool(reactor) defcounter(): '''This function gets called once a second and prints the progress at one second intervals. ''' print("Requests: {} generated; {} made; {} done".format( req_generated, req_made, req_done)) # reset the counters and reschedule ourselves req_generated = req_made = req_done = 0 reactor.callLater(1, counter) defbody_received(body): global req_done req_done += 1 defrequest_done(response): global req_made deferred = treq.json_content(response) req_made += 1 deferred.addCallback(body_received) deferred.addErrback(lambda x: None) # ignore errors return deferred defrequest(): deferred = treq.post('http://api.host/v2/loadtest/messages', auth=('api', 'api-key'), data={'from': 'Loadtest <test@example.com>', 'to': 'to@example.org', 'subject': "test"}, pool=pool) deferred.addCallback(request_done) return deferred defrequests_generator(): global req_generated while True: deferred = request() req_generated += 1 # do not yield deferred here so cooperator won't pause until # response is received yieldNone if __name__ == '__main__': # make cooperator work on spawning requests cooperator.cooperate(requests_generator()) # run the counter that will be reporting sending speed once a second reactor.callLater(1, counter) # run the reactor reactor.run()输出结果：
2013-04-25 09:30 Requests: 327 generated; 153 sent; 153 received 2013-04-25 09:30 Requests: 306 generated; 156 sent; 156 received 2013-04-25 09:30 Requests: 318 generated; 184 sent; 154 received
2013-04-25 09:30 Requests: 327 generated; 153 sent; 153 received 2013-04-25 09:30 Requests: 306 generated; 156 sent; 156 received 2013-04-25 09:30 Requests: 318 generated; 184 sent; 154 received
“Generated”类的数字代表被Twisted反应器准备好但是还没有发送的请求。这个脚本为了简洁性忽略了所有错误处理。为它添加超时状态的信息就留给读者作为一个练习。
这个脚本可以当做是一个起始点，你可以通过拓展改进它来自定义特定应用下的处理逻辑。建议你在改进的时候用 collections.Counter 来替代丑陋的全局变量。这个脚本运行在单线程上，想通过一台机器压榨出最大量的请求的话，你可以用类似 mulitprocessing 的技术手段。
愿你乐在压力测试！
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