Fork/Join task (jsr166y) and speed-up

Question

I tried to speed up some toy examples code using jsr166y. I have not been able to reach any success, whatever the class/methods I used. I even tried the code featured in the IBM developer works paper without any success.

Do you have some positive experience with this new framework ? Are there some better implementations ?

Edit: I runned it in a quad-core machine. I have very good speed-up with the classical ExecutorService + Callable jsr166 API.

Answer 1

Its largely processor dependent.. If you don't have a multi-core machine, you probably wouldn't see much improvement. Probably wouldn't expect a whole lot with just 2 cores, either.

However, even on old hardware, I think the framework might be useful for I/O bound tasks, where you could sequentially call remote services, or call them in parallel... Imagine implementing a browser where you first download the raw HTML and then you start retrieving all the resources (images, etc.) it references. The more you can retrieve in parallel, the faster the browser. Fork-Join might be a good choice for something like that.