Processing 1.0 - Processing Discourse - What happens to millis() after 49 days?

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Index › Programming Questions & Help › Syntax Questions › What happens to millis() after 49 days

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What happens to millis() after 49 days? (Read 351 times)

RickiG Junior Member Offline Posts: 81	What happens to millis() after 49 days? Mar 2^nd, 2009, 3:34pm Hi I was just wondering what happens when a sketch has been running for 49 days and the int that stores it is theoretically filled up? 4294967295/1000/60/60/24 = 49 days I guess the same goes for frameCount(), well and a also in other languages. Nothing important, just a thought
	Regards Ricki

PhiLho

Re: What happens to millis() after 49 days?
Reply #1 - Mar 2^nd, 2009, 4:48pm

There was a bug in Windows NT which has troubles after 49 days... Of course, Microsoft corrected that a long time ago.

Java actually uses a long, so do Processing in its internal variable millisOffset (time stamp when the sketch starts).
But indeed, millis() return an int, so we will have an overflow. After 25 days, since int is signed. So value will become negative, probably.
Consequences depend on program, of course.
frameCount should take longer to have a problem...

Now, except perhaps for servers, computers rarely run more than a month without being restarted. At least with Windows, some critical updates restart forcefully the compter!
Even so, you even more rarely run graphical applets that long.

But hey, that's a problem to take in account in some (rare) cases, you are right to rise it.

RickiG

Re: What happens to millis() after 49 days?
Reply #2 - Mar 2^nd, 2009, 5:51pm

Thank you for the answer PhiLho:)

I actually never gave it much thought, before today, depending on the language you will get different exceptions when running into to an overflow, I just assumed that the core classes took these things into account.

I guess you are right that the OS will need a restart before the sketch will, but still, in a perfect world the app Im doing should sit in the background and do it's little thing forever.

Hmm maybe I'll make it throw an exception and make a bit of "noise" so it will be restarted by someone.

Regards Ricki

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