Why pipelining in firefox does not seem to work?

Question

To verify that using http pipelining can optimize the speed of loading resources, I made a test as follows:

Open Firefox on Mac, in config change max connection per server to 1, then I open a test page which loads 12 images. I got the following figure:

The browser load each image one by one and 12 images cost about 12 seconds to load(i add 1 sec delay for each image).

Next, I turn on pipelining in Firefox, and refresh the page. I got the following figure:

I can see there is no blocking at all. All requests are pipelined. I suppose the total time of loading will be shortened but unfortunately it's the same with that of no pipelining. So I doubt the pipelining doesn't seem to work.

I want to know why and how can I fix it. I use apache server. Are there any configs need to be made in Apache?

Answer 1

As wiki said,

The pipelining of requests results in a dramatic improvement in the loading times of HTML pages, especially over high latency connections such as satellite Internet connections. The speedup is less apparent on broadband connections

Your test is based on a typical broadband connection. It is so short (a moment can be ignored) for the server to receive each request and every time it sends such a big picture, whole bandwidth of the connection is occupied.

So, you can retry your test with:

1. High latency on each request.
2. Many tiny files as resources to response.