If they did, we wouldn't be having this discussion to begin with!

This is a bit vague to really reply to very specifically, but yes, this is hard. Which is why quite some people work in this area. It's rather valuable to do so at Firefox-scale.

Even if the majority of time it generates the “same” failure mode, it can still sporadically generate a rare execution trace.

This doesn't matter that much because the "same" failure mode already allows you to see the bug and fix it.

Hint: No-one is claiming memory is to blame for 100% of the Firefox crashes. No-one is claiming it's 99% either.

Without knowing more about your configuration, it's hard to give advice, but definitely worth trying with a clean profile first.

If you don't report this problem upstream it will never get fixed, as obviously no-one else is seeing this. Firefox has a built-in profiler that you can use to report performance problems like this.

Any memory allocation failing within the browser forces an instant crash unless the callsite explicitly opts in to handling the allocation failure.

"Check malloc failure" is an opt-out feature in browsers, not opt-in. It's the same in Chromium. Failing to check would cause too many security issues. (One more reason new stuff tends to prefer Rust, etc)

Not sure if it's a coding issue in the Firefox version of Dark Reader, or it's hitting some slow path in Firefox itself.

Or missing out on new anti-fingerprinting and anti-tracking improvements. Note that adblockers don't generally do the former.

It's not an issue for these .deb packages because they enable the (experimental) forkserver.

Recent versions of Firefox allow you to block some stuff like that: https://support.mozilla.org/en-US/kb/identify-problems-third...

Though it's possible they use different code injection tricks to make blocking impossible. (You can't block Defender from listening to events for example)

Getting macOS to OOM is actually pretty difficult, we probably want to unload tabs before that point for performance (swap!) reasons, but that's also harder to measure very reliably.

The feature stops (or reduces the likelyhood) of that happening. It literally is made to trigger in a situation where the alternative is to crash.

>So, if I want to disable this, I should set a big number to the browser.low_commit_space_threshold_mb pref in about:config, right?

This will ensure that you crash and have to reload all of your tabs instead of the oldest ones, yes :-)

This one works well enough that we can default it on :-)

The previous one didn't reliably detect low memory situations and you could crash with OOM before it ever triggered. The article goes into detail about the various signals that have to be monitored on Windows. We had to do some work on gathering the metrics and correlating with crash data to determine when to trigger.

If it's not reliable, the browser unloads tabs when it's not needed, and that's way more annoying.

As the article explains, if you have enough swap you'll never trigger this. It activates right before you'd have crashed otherwise.