很久以前,我写了一个web-spider,我用多线程使并发请求同时发生。那是在我年轻时使用Python的时候,那时我还不知道GIL以及它给多线程代码带来的麻烦(IE,大多数时候这些东西最终都被序列化了!)……
我想重做这段代码,使其更健壮,性能更好。我基本上有两种方法可以做到这一点:我可以使用2.6+中新的多处理模块,或者我可以使用某种基于反应堆/事件的模型。我宁愿选择后者,因为它更简单,更不容易出错。
所以这个问题涉及到什么样的框架最适合我的需求。以下是我目前所知道的一些选择:
Twisted: The granddaddy of Python reactor frameworks: seems complex and a bit bloated however. Steep learning curve for a small task. Eventlet: From the guys at lindenlab. Greenlet based framework that's geared towards these kinds of tasks. I had a look at the code though and it's not too pretty: non-pep8 compliant, scattered with prints (why do people do this in a framework!?), API seems a little inconsistent. PyEv: Immature, doesn't seem to be anyone using it right now though it is based on libevent so it's got a solid backend. asyncore: From the stdlib: über low-level, seems like a lot of legwork involved just to get something off the ground. tornado: Though this is a server oriented product designed to server dynamic websites it does feature an async HTTP client and a simple ioloop. Looks like it could get the job done but not what it was intended for. [edit: doesn't run on Windows unfortunately, which counts it out for me - its a requirement for me to support this lame platform]
我还遗漏了什么吗?当然,一定有一个库在那里,适合一个简化异步网络库的甜蜜点!
[edit: big thanks to intgr for his pointer to this page. If you scroll to the bottom you will see there is a really nice list of projects that aim to tackle this task in one way or another. It seems actually that things have indeed moved on since the inception of Twisted: people now seem to favour a co-routine based solution rather than a traditional reactor / callback oriented one. The benefits of this approach are clearer more direct code: I've certainly found in the past, especially when working with boost.asio in C++ that callback based code can lead to designs that can be hard-to-follow and are relatively obscure to the untrained eye. Using co-routines allows you to write code that looks a little more synchronous at least. I guess now my task is to work out which one of these many libraries I like the look of and give it a go! Glad I asked now...]
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