Hi,

I have a tool that depending on input may need huge amounts of memory. The problem is that the system may run out of memory. The default configuration of Windows starts swapping at this point, and when that's not enough, the default configuration causes a dynamic resize of the swap file, which effectively freezes the entire system. On 32 bit Windows, the address space eventually runs out and allocations fail, causing my app to receive a System.OutOfMemoryException, but that may not happen on 64-bit Windows. At least not in acceptable time. The result is that my app can cause the system to freeze for an unknown amount of time where the only out is a hard reset. I personally think this is a bad and dangerous behavior of Windows, at least for a default, but it is what it is so I need a workaround. It's not realistic to reduce memory usage or switch to some file based solution, manual or memory mapped files.

What I want to do at this point is to warn the user when the app is about to use large amounts of memory and ask for confirmation before continuing. To do this, I need to figure out how much memory is "safe" to use at the moment. If the user has 4GB is his system, then perhaps I should only use 1.5GB before warning. If the user has 32GB, I could likely use 20+ without issues. I should probably have some level of respect for other applications running.

How would you do this? What system and application properties should I be looking at? Working set, virtual memory usage, commit size, etc?

You could write parts of the memory you are using to a file, I doubt you need 2 gb of memory all the time. This is slower tho. Guess you could also write some kind of compresser for memory.

File based operation is not realistic at all right now. Splitting the input into smaller chunks will be possible at some point in the future, but not soon enough, and doing that mat degrade the usefulness of the tool. Imagine having a giant map and the tool was meant to show pathfinding data, but had to load only parts of the navmesh at a time. There are lots of paths you could find/see, but there are also some paths that couldn't be found/displayed. The results would still be useful but incomplete, and sometimes those missing pieces are what matters.

What we need is a quick and hopefully temporary way to not crash the users system when that system can't handle the input, without limiting operation on systems that can handle it.