UPDATE: I've updated some of the numbers below to reflect corrections for a testing error. Let's just say to be sure not to benchmark with any external links in your test pages (because if you do use external links you'll obviously be benchmarking the external server too, which is not what we want in this case). To summarize the effect of these corrections - having lighttpd in front of Apache and pipelining actually provide a substantially larger boost in performance than I had indicated before. Other than that the results are the same.

So things with my first attempt at benchmarking HTTP pipelining did not go exactly as planned. It turns out that if two different domains/subdomains you are using for content on your site are pointing to the same IP, based on previous testing, it looks like browsers (at least FireFox) will not pipeline requests (e.g., create more concurrent requests to your site) because it considers the requests as being from the same origin. In order for a browser to pipelining requests at all, they seem to require two domains/subdomains which are using two separate/unique IPs. If you read the Wikipedia entry for hostnames this all makes sense, as it indicates domains are associated with IP's, and browserscope's testing of browsers checks for "Connections per Hostname", not "Connections per Domain".

After figuring out how to get requests to pipeline correctly, I re-benchmarked all the configurations from the first article . Everything from that article regarding lighttpd is still holds true, so without covering those aspects again, here's the updated benchmarks and notes for browser request pipelining:

• Once the conditions for request pipelining was setup correctly there were discernable performance implications. Some of them I definitely wasn't expecting. On the one end of the spectrum, with browser pipelining working (via string replacement of domains within the rendered HTML) and lighttpd serving the static files there was an 11% increase in throughput vs not using the pipelining methods. So static file serving ='s good, and static file serving + HTTP pipelining ='s a little better.

  This is not where the story ends with pipelining however, as there was a net performance decrease by enabling pipelining with all configurations which did not use a separate static file server! (in my case lighttpd on the same machine)

Categories: Drupalperformanceoptimizationlighttpd