[xterm-addon-web-links] Typing with link highlighted causes serious performance impact

[raiden-dev]

Details

• Browser and browser version: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/118.0.0.0 Safari/537.36
• OS version: Windows 11 Pro / 22H2
• xterm.js version: Any version with loaded xterm-addon-web-links. Tested on version bundled with ttyd: "xterm": "^5.3.0, "xterm-addon-web-links": "^0.9.0".

Steps to reproduce

0. Make a terminal with loaded WebLinksAddon from xterm-addon-web-links package.
1. Move mouse pointer to any link in xterm.js canvas to highlight it.
2. Try to type anything. Overall performance will degrade with every new keypress and may result to tab crash.

Here's the traced performance profile: Trace-20231014T084401.json

[jerch]

@raiden-dev Thx for finding this one, can repro it as long as the typed content adds the the link while the link is hovered. This really feels like some exp runtime issue, the perf degrades really fast. Interesting sidenote - the perf resets if I re-hover the link and continue typing.

From a first glance at devtools it seems the time gets eaten in this method:

xterm.js/src/browser/Linkifier2.ts

Lines 257 to 268 in a5646a5

	private _clearCurrentLink(startRow?: number, endRow?: number): void {
	if (!this._element || !this._currentLink || !this._lastMouseEvent) {
	return;
	}
	// If we have a start and end row, check that the link is within it
	if (!startRow || !endRow || (this._currentLink.link.range.start.y >= startRow && this._currentLink.link.range.end.y <= endRow)) {
	this._linkLeave(this._element, this._currentLink.link, this._lastMouseEvent);
	this._currentLink = undefined;
	disposeArray(this._linkCacheDisposables);
	}
	}

but that code looks rather innocent to me. Maybe there is something off with this._linkCacheDisposables, not sure yet.

[jerch]

I cannot repro it on our demo, works with all renderers as expected not showing any quadratic/exp runtime growth. This is somewhat weird, as there were no substantial code changes to the linkifier or the web-links addon almost in a year.

@Tyriar My best guess here is, that this was also solved with #4814. Gonna close the issue, as master does not exhibit the toxic growth anymore.

[Tyriar]

Yep #4814 was a pretty bad bug.