Why do game engines break when they are kept running for days?

[VirusDumb]

So a few months ago I found this video which is about some paranormal activity happening in NFSMW 2005

But here's the thing, that guy kept the game open for 7 days, that's equals to 168 hours, and I can't afford to pay the electric bills after keeping my PC on for such a long time, so I asked about this on discord servers related to NFS, well nobody wanted to keep their PC on for 168 hours, so all I got was theories of what might have caused it to happen, and the only believable one was from a mod developer saying "The game engine might have been freaking out as it was running for so long"

 

And today I found this video 

 

 So my question is, why do they happen? And are there any other discovered "game breakers" which occurred after somebody left on their game and went to a vacation maybe?

[tkitch]

memory leaks and poor cleanup, generally

[da na]

As the previous comment said it's usually due to memory leaks. With ECC memory I can't really test this for myself but it could also be because of the game engine being buggy.

[A51UK]

9 minutes ago, Mel0nMan said:

As the previous comment said it's usually due to memory leaks. With ECC memory I can't really test this for myself but it could also be because of the game engine being buggy.

EEC memory have nothing to do with memory leaks, so you can test this out.EEC memory old deal with error when data go to and from RAM (e.g. a bit is in the wrong flop). Aslo EEC memory cannot not stop a memory leaks,

 

What  memory leaks is when a program allocations an object in memory but forgot to released when no longer needed. A good example of this could be a game that keep make a new object in game then remove the object but forgot to release the memory that the object was allocations, so when a new object is made it take up new area of memory and not the old object  memory area as it was not released. When it keep happen e.g. maybe over a longer time the RAM that the program get allocations or available will get full up and the program will crash.

 

So it a bug in the game engines that make the memory leaks. 

 

[Spotty]

29 minutes ago, SeAsOn3 said:

 So my question is, why do they happen? And are there any other discovered "game breakers" which occurred after somebody left on their game and went to a vacation maybe?

There's a barrier skip in a zelda game where they take advantage of a glitch in an idle animation of the character that does not properly loop back to its starting position. It's missing a frame in the animation loop which means each time the idle animation loops the characters position changes very slightly. This can allow players to move through walls as the game isn't performing its normal wall collisions checks during the idle animation... But because it's only moving very very slightly it takes a very very long time for it to move the character any meaningful distance.

 

This video explains it in detail and was where I found out about it...

Skip ahead to 4:30 if you know how low% speedrun categories work.

[Zodiark1593]

Games are typically produced under extremely tight schedules. Time spent fixing an issue that 99.9% of players will never happen across takes away from resources, and has the very real potential of the fix introducing problems itself. 

[YoungBlade]

In a game, every single frame, a ton of things happen. In any game that has physics, like the examples you gave, there are hundreds or thousands of calculations taking place. It can be difficult to write the code in such a way that a mistake never happens.

 

Think about this: numbers in a computer are stored in a fixed amount of space. Often just 32 bits, sometimes 64 bits. When you only have a fixed number of bits to work with, rounding will have to happen. By default, a lot of coding languages use truncation for rounding - so it always rounds down.

 

If a scene is loaded for just 15 minutes, tiny mistakes like that won't make a difference. If a scene is loaded for 15 days, those tiny mistakes will build up over time.

 

Frankly, it wouldn't be worth the effort to make sure that those sorts of issue never crop up. We aren't dealing with scientific physics calculations that are meant to be run for months and that need an extreme level of precision in order to be valid.

[Amias]

The bigger question here is this line:

 

Quote

that's equals to 168 hours, and I can't afford to pay the electric bills after keeping my PC on for such a long time,

Are you living watt to watt? What is this?

[wasab]

Pretty sure memory leaks is purely a software issues. It generally means the software is not freeing up discarded memory which can occur if the game developers manually manages the memory allocation for a game/game engine.