Memory Leak with an XMLHttpRequest and setInterval

Question

Here\'s some code that I run on Google Chrome 19.0.1061.1 (Official Build 125213) dev:

Answer 1

In the first one, you're instantiating a new XMLHttpRequest object on each call to the iterator function. The request objects will stick around at least until the HTTP requests complete. Initiating 200 HTTP requests per second is going to clog the browser up something fierce, since it won't actually perform all the requests; there's a limit to how many concurrent connections it'll open.

Answer 2

In your first example, you are calling a new instance of XMLHttpRequest() with each interval. In the second one, you instantiate a copy one time and use it throughout the life of the code. That's why in the first example you run out of memory.

Answer 3

How long does this http call take? if this takes longer then 50ms (which is a very shot amount of time) then the first case will be creating more and more pending requests while then second case you are reusing the same XMLHttpRequest which may have the effect of canceling the previous call.