使用Twisted Python和Treq进行 HTTP 压力测试_python教程_开发教程

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。

(责任编辑：好模板)