752861 - Consider a separate pref for enabling the GC/CC API

Status: RESOLVED DUPLICATE of bug 773734

(Core :: JavaScript Engine, defect)

Description

[Henrik Skupin [:whimboo][⌚️UTC+2] (away July 24th - August 16th)]

Right now you have to set the pref 'javascript.options.mem.log' to enable logging of GC/CC data. This is still bad even with the API in-place now, because whenever you want to observe the Error Console for other stuff, it is swamped with a lot of messages you do not want to receive.

As requested in an issue for memchaser would it be possible to introduce a separate pref to be used for enabling/disabling the GC/CC API?

Comment 1

[Sean Newman]

It was me, who requested this for memchaser, but you've said your extension won't work if GC/CC output data won't be accessible. And here you suggest a separate pref for enabling GC/CC API.
What does it mean? That the pref will be created to enable/disable GC/CC? As far as I understand - this will stop GC/CC output completely and that's not what I requested.

I requested to change the source for the GC/CC output data from Error Console to somewhere else, so it would still work (and your memchaser will work too), but the Error Console would remain clean.

If that is exactly what you meant by this bug - sorry, but the summary says another thing.

Comment 2

[Henrik Skupin [:whimboo][⌚️UTC+2] (away July 24th - August 16th)]

(In reply to Sean Newman from comment #1)
> It was me, who requested this for memchaser, but you've said your extension
> won't work if GC/CC output data won't be accessible. And here you suggest a
> separate pref for enabling GC/CC API.

That's correct. Since Firefox 14 we do not necessarily have to use the console messages to parse the GC/CC data. With bug 531396 we now even have observer notifications. But sadly those notifications only get send if the memory logging pref is enabled. 

> What does it mean? That the pref will be created to enable/disable GC/CC? As
> far as I understand - this will stop GC/CC output completely and that's not
> what I requested.

I request a separate pref for GC/CC observer notifications. In that case we do not have to enable 'javascript.options.mem.log' and as result the Error Console will not be cluttered by all those GC/CC messages.

> I requested to change the source for the GC/CC output data from Error
> Console to somewhere else, so it would still work (and your memchaser will
> work too), but the Error Console would remain clean.

That's exactly what we already have since Firefox 14, but both methods are still tied to each other and need to be decoupled if possible.


One more thing, do we have an idea about the overhead for GC/CC observer notifications? Could we let them be enabled all the time?

Comment 3

[Andrew McCreight [:mccr8]]

I think MemChaser is more of a Snappy thing than a MemShrink thing at this point.