"TS parser failed" when opening large files

[larsks]

I am using helix to open a large (22MB) JSON file. The open file does not receive any syntax highlighting, and helix reports (in helix.log):

2024-12-15T12:28:35.974 helix_core::syntax [ERROR] TS parser failed, disabling
TS for the current buffer: Err(Cancelled)

Opening smaller files works without a problem. The file is valid JSON (as confirmed with e.g. jq, json_verify from yajl, python -m json.tool).

[kirawi]

This is intentional to avoid Helix being unusable when syntax highlighting takes too long.

[larsks]

What determines the threshold for whether or not syntax highlighting is disabled? Is that adjustable? Is there a way to get some sort of notification when this happens?

Looking at other editors...

• neovim takes a couple of seconds to open the file, but does successfully open and highlight the file. It displays the message "Big file detected. Some neovim features have been disabled."
• vis opens the file with no noticeable delay and highlights it correctly.
• kakoune opens the file with no noticeable delay and highlights it correctly.

It looks like helix is the only editor that actually refused to highlight the file.

[TornaxO7]

What determines the threshold for whether or not syntax highlighting is disabled?

A simple timeout.

Is that adjustable?

Looks like not, but I'm not really familiar with the codebase.

Is there a way to get some sort of notification when this happens?

AFAIK:

[kirawi]

Tree-sitter has much higher time and space complexity compared to regex AFAIK