Bash: how to simply parallelize tasks?

Question

I'm writing a tiny script that calls the "PNGOUT" util on a few hundred PNG files. I simply did this:

find $BASEDIR -iname "*png" -exec pngout {} \;

And then I looked at my CPU monitor and noticed only one of the core was used, which is quite sad.

In this day and age of dual, quad, octo and hexa (?) cores desktop, how do I simply parallelize this task with Bash? (it's not the first time I've had such a need, for quite a lot of these utils are mono-threaded... I already had the case with mp3 encoders).

Would simply running all the pngout in the background do? How would my find command look like then? (I'm not too sure how to mix find and the '&' character)

I if have three hundreds pictures, this would mean swapping between three hundreds processes, which doesn't seem great anyway!?

Or should I copy my three hundreds files or so in "nb dirs", where "nb dirs" would be the number of cores, then run concurrently "nb finds"? (which would be close enough)

But how would I do this?

Answer 1

Answering my own question... It turns out there's a relatively unknown feature of the xargs command that can be used to accomplish that:

find . -iname "*png" -print0 | xargs -0 --max-procs=4 -n 1 pngout

Bingo, instant 4x speedup on a quad-cores machine :)