The Mac OS X Internals book states that the maximum process identifier is 30,000 and after that the kernel will start re-using pids. But checking on my own system, via:
ps a | grep ps | grep -v grep | awk '{print $1}'
I can see that I have pids that go higher. Does anyone know if there is a pid_max explicitly set somewhere, like in Linux?
Best Answer
Looking at sys/proc_internal.h in xnu-1699.24.23, I find that PID_MAX is 99999. The value is used in kern_fork.c in the function
forkproc. Looking at that function, process IDs are not assigned equal to PID_MAX, so the highest possible pid is 99998.