“Proxying” a lot of HTTP requests with Node.js + Express 2

Timeouts were caused by using http.globalAgent which by default can process up to 5 concurrent requests to one host:port (which isn't enough in my case).

Thouthands of requests (instead of tens) were sent by ab (Wireshark approved fact under OS X; I can not reproduce this under Ubuntu inside Parallels).

You can have a look at node-http-proxy module and how it handles the connections. Make sure you don't buffer any data and everything works by streaming. And you should try to see where is the time spent for those long requests. Try instrumenting parts of your code with conosle.time and console.timeEnd and see where is taking the most time. If the time is mostly spent in javascript you should try to profile it. Basically you can use v8 profiler, by adding --prof option to your node command. Which makes a v8.log and can be processed via a v8 tool found in node-source-dir/deps/v8/tools. It only works if you have installed d8 shell via scons(scons d8). You can have a look at this article to help you further to make this working.

You can also use node-webkit-agent which uses webkit developer tools to show the profiler result. You can also have a look at my fork with a bit of sugar.

If that didn't work, you can try profiling with dtrace(only works in illumos-based systems like SmartOS).