How to write a program to find the fastest working proxy server?

My college has 5-6 proxy servers and occasionally some of them are down or slow. I would like to write a program that would help me determine the fastest available proxy server.开发者_如何学JAVA Does there exist any application for this already?

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First of all, a quick Google reveals that this kind of software already exists. I haven't tried it though, so I can't say anything about the quality of those.

If you decide to make one yourself, here is a rough sketch on how you could do it with .NET:

1. Maintain a list of proxy server candidates
2. Issue requests (to the same resources for all servers) through these proxies using HttpWebRequest and setting the Proxy property.
3. Measure average request time.
4. Set the browser proxy setting to the server that turned out to be fastest.