672694 - Add memory reporters to count compartments

Status: RESOLVED FIXED

(Core :: XPConnect, defect)

Description

[Nicholas Nethercote [inactive]]

I often count the number of compartments manually.  It'd be nice (and easy) to automate this.

Comment 1

[Kyle Huey (Exited; not receiving bugmail, old account, do not use)]

Should we telemeterize this?

Comment 2

[Nicholas Nethercote [inactive]]

Good idea, I'll do that.

Comment 3

[Nicholas Nethercote [inactive]]

Attachment: patch

This patch adds the js-compartment-count reporter.

It doesn't telemeterize the counter, however.  TelemetryPing.js has code that assumes that any UNITS_COUNT reporter reports a number that always increases, and so reports the change between pings.  This makes sense for the page-fault counters, but not for js-compartment-count.  I'll defer that to a follow-up bug (and assign it to jlebar, who implemented the current behaviour.)  We might need to distinguish between UNITS_COUNT and UNITS_COUNT_INCREASING.

Comment 4

[Nicholas Nethercote [inactive]]

Attachment: patch, v2

I split this into two reporters:  js-system-compartment-count and js-user-compartment-count, because knowing the split is useful, and summing them to get the overall count is trivial.

Comment 5

[Nicholas Nethercote [inactive]]

http://hg.mozilla.org/integration/mozilla-inbound/rev/9bb30262e230

Comment 6

[(no longer active)]

http://hg.mozilla.org/mozilla-central/rev/9bb30262e230

Comment 7

[Nickolay_Ponomarev]

The user vs system terminology (I realize it comes from the names in the code) is confusing.

Do I understand correctly that the 'system' compartment basically counts compartments for the chrome code (as in "System principal")?

Comment 8

[Nicholas Nethercote [inactive]]

(In reply to comment #7)
> 
> Do I understand correctly that the 'system' compartment basically counts
> compartments for the chrome code (as in "System principal")?

That's right.  It also includes the 'atoms' compartment.