846979 - Collect telemetry for js_ReportOverRecursed count

Status: RESOLVED INCOMPLETE

(Core :: JavaScript Engine, defect)

Description

[Gregory Szorc [:gps]]

In bug 845842 we are dealing with stack blowout issues. Conversing with jimb on IRC it is apparent we don't know how often this occurs in the real world. He suggested I file this bug to report how often js_ReportOverRecursed is called. A similar telemetry probe would be reports on max stack sizes.

Comment 1

[Luke Wagner [:luke]]

We would get a number, but it won't be a particularly useful number, nor will its trends.  I've seen many real sites that contain bugs that cause infinite recursion terminated only by the over-recursed exception.  A pattern I've seen while debugging more than once wraps the infinite recursion in a try catch and ignores the exception, causing it to be hit quite frequently.

Comment 2

[Gregory Szorc [:gps]]

Can we capture just chrome JS? That's what I really care about.

Comment 3

[Jim Blandy :jimb]

How about 'pages that ever blow out the stack', then? That is, only count it once, no matter how many times the exception is thrown on an individual page.

Counting distinct URLs seems like way more work than necessary; counting it per global object - such that reloading the page causes the exception to be counted again - would probably be fine.