2542 seems like an arbitrary number:
I shut all programs down except the one terminal window I was running my test from and I got to 2545
, that told me it was an arbitrary limit.
To get the number of threads for OSX 10.6.3 you do:
> sysctl kern.num_threads
kern.num_threads: 2560
and
> sysctl kern.num_taskthreads
kern.num_taskthreads: 2560
The 2560
number matches up with the 2542
and 2545
because there are obviously other threads running in the background.
According to the official documentation kern.num_taskthreads
can not be adjusted in the desktop version of OSX.