The reload operation takes up a lot of memory until the computer freezes

[xpeng2333]

Summary

Opening a file with a size of 500M, executing the reload operation will take up much more memory than the file size and keep increasing until all the memory is used up

Reproduction Steps

I tried this:

1. hx 1.txt
2. reload
   I expected this to happen:
   reload 1.txt
   Instead, this happened:
   hx used up all memory

Helix log

~/.cache/helix/helix.log

please provide a copy of `~/.cache/helix/helix.log` here if possible, you may need to redact some of the lines

Platform

macOS

Terminal Emulator

zsh 5.8.1

Helix Version

helix 22.08.1

[the-mikedavis]

It isn't an infinite amount of memory but it is quite a lot: for a text file with ~503MB, I see around 21GB of memory usage during the reload and 1GB after.

It looks like helix_core::diff::compare_ropes is the culprit for the increased CPU usage at least, and probably the increased memory usage too:

[kirawi]

I'm assuming that this is because of the timeout. After 1 second, all diff operations turn into insertions and deletions as a fast path. And since this is per char, it can get pretty big.

Alternatively, these lines may be the culprit:

helix/helix-core/src/transaction.rs

Lines 476 to 478 in e16c632

	let (lower, upper) = changes.size_hint();
	let size = upper.unwrap_or(lower);
	let mut changeset = ChangeSet::with_capacity(2 * size + 1); // rough estimate

[xpeng2333]

Thanks for your reply. It seems that I misunderstood the reload operation. I thought it was just reopening the file.

[kirawi]

The rsync algorithm is an option for more efficient reloading as well.