Limit RAM usage with a config option?

[Wizek]

Hello,

I really quite like the many of the concepts in acid-state. But I am reluctant to use it (e.g. for server applications) because I know it needs to keep all data in RAM all the time. And while the server might not have many users -- if it happens that it does have later on, RAM might become an issue, I am concerned.

Would it be possible to configure acid-state in such a way to tell it "Use at most 2 GB of RAM and not a bit more!"? And what I would expect acid-state to do when it reaches 2GB is to drop the least accessed bits from memory at once, and re-read them from disk iff/when they are accessed from other parts of the code, on demand.

Would this be possible? And if so, could this be implemented easily?

[lemmih]

This is the same as swapping, isn't it? I don't think it can be done without killing the performance.

[stepcut]

We have casually discussed the idea of using something like mmap to allow developers to control what is currently in memory and what is currently on disk. Or perhaps something like pipes to stream records from disk.

However, making that work is almost certainly a pretty significant project. We need a masters student looking for a thesis I think :)