Recursion limits

[Rhyono]

My script checks some things every few seconds, and it can run for many hours. After about 4 hours, I got a recursion error from PixelGetColor. Is it just reaching a limit on the number of times it finds it acceptable to do it, or is it actually finding a memory leak? If it's the former: can I shut off recursion limits?

[BrewManNH]

You are reaching the recursion limit and there's no way to shut it off. Your script is written poorly and needs to be fixed because whatever you're doing is causing it to crash.

[Exit]

If you would show your code, we might help you.

[Mat]

I'm guessing somewhere you are doing something like:

Func CheckSomething()
    PixelGetColor(...)
    Sleep(A bit)

    CheckSomething()
EndFunc

That kind of code pattern is the most likely way you'd hit the recursion limit. It's very easy to replace with a single loop, which would be the correct way to do it.

Edit: You are actually pretty close when you say its a memory leak. Every time you call a function its added to the stack, and when you return it is popped off the stack. If you keep calling functions the stack just grows, never being unrolled (like a memory leak: allocating but not de-allocating).

Edited December 12, 2012 by Mat

[Rhyono]

@Mat It does quite a bit more than that, but that is the basic structure. Switching it to a While would be easy enough; I just figured I'd get the recursion error either way.

[Mat]

@Mat It does quite a bit more than that, but that is the basic structure. Switching it to a While would be easy enough; I just figured I'd get the recursion error either way.

A while loop is what we would call iteration. Generally iteration is preferred: There is only a finite stack (hence your recursion limit), and at a low level there is a lower overhead (though I wouldn't worry about this in AutoIt).

Recursion is generally the option you use when iteration doesn't work. When working with nested structures (binary trees, linked lists etc.) which aren't common in AutoIt. Sometimes recursion can be a lot prettier than iteration as well.

[Jos]

@Mat It does quite a bit more than that, but that is the basic structure. Switching it to a While would be easy enough; I just figured I'd get the recursion error either way.

This really means you still don't understand the basics of iterations and recursion and have a logic problem in your script.

[gruntydatsun]

Example using a while loop:

====================

There is a drip in the ceiling and you deploy clone 1 catch the drip

When the next drip falls, clone 1 catches it and so on.

After a thousand drips, you still only have one clone in the room.

Example using recursion:

====================

There is a drip in the ceiling and you deploy clone 1 to catch the drip

When the next drip calls, clone 1 deploys another clone called clone 2 to catch this drip.

Meanwhile clone 1 just stands around taking up room.

When the next drip falls, clone 2 calls another clone into the room to catch it (clone 3)

Meanwhile clone 2 just stands around taking up room.

This repeats until your room is stacked to the ceiling with clones and you can't fit anymore in.

Sweet example

[Rhyono]

@Jos "Still" refers to the present; prior to your lovely snide remark, Mat already did a good job of explaining, and after your remark gruntydatsun did as well.