High VIRT memory used by file manager

Question

I'm using elementary OS and it's default file manager Files.

I've noticed that after a while of usage, htop shows that pantheon-files (how the app is named) consumes over 10Gb of VIRT memory.

This value increases every time I open an image and never seems to stop.

I'm not familiar with VIRT memory management so my question is: is this behaviour expected and/or somewhat normal for a file manager? Or is this a memory leak?

Answer 1

It's neither expected nor normal. But there is absolutely no reason you should care. You should not have particular expectations about how a a file manager uses virtual memory. And I don't think there are usage patterns that are particularly normal or abnormal.

It's all going to come down to tiny design decisions. Do you memory map files? When do you unmap that?

There is no reason anyone should care absent evidence there's some kind of problem. Virtual memory on a 64-bit OS is so ridiculously cheap that there's absolutely no reason you should try to treat it as a scarce resource. You can make tradeoffs entirely in the other direction, and programmers do.

Answer 2

I'm not familiar with Elementary and Files, but this is normal for processes in general. The VIRT refers not (necessarily) to physical RAM used, but what the size of the mapped address space is for that process. This address space will include physical RAM, shared objects and files open on disk, etc. For example, dropbox-3.6.7 on my PC VIRT = 3GB, but RES = 100M, i.e. 100MB physical memory is in use, and ~3GB files have been accessed. If there was a memory leak you'd likely see RES increasing slowly. If you like take a look at this document on TLDP, it explains everything rather well.

VIRT = Virtual process size. RAM, files, everything.

RES = Resident size in physical memory

SHR = Amount of VIRT which is shared, i.e. can be used by other processes.

HTH!