First and foremost, don't re-invent the wheel. Unless you have a specific reason for not doing so, you should be using LWP::UserAgent for this.

The short answer to the "why?" part of your question is this: HTTP/1.0 works on a single request/response model. With HTTP/1.1, you could use Keep-Alive to work around this. But generally, for simple HTTP requests you go one at a time.

A great advantage to the LWP set of classes is that the user-agent can be configured to try and use keep-alive, falling back to single-transaction model if needed. Really, you are much better off using this.

--rjray