NullPointerException

Computercraft doesn't seem to like it when i try to use infinite while loops in parallel functions.

Simplified code:

running = true
function threadOne()
	while running do
		--Logic here
	end
end
function threadTwo()
	while running
		--logic here
	end
end
parallel.waitForAny(threadOne, threadTwo)

it runs for a few seconds, then it crashes with a JVM NullPointerException error

There should be no problem with doing that, maybe it's another part of the code wich cause it. I use coroutines (like parallel) a lot all of them running in an infinite loop (I had almost 30 running) and never crashed.

Turns out that not having a sleep/processing made one of the functions hog all the emulator time, causing in NullPointer from the other threads.

Parallel is just a wrapper around coprocess. You need to call a function that internally does a yield, such as a pull, sleep, queue, or just an interface command, in order to not freeze the processor.