751509 - Don't assert that about:memory percentage reporters are less than 100%

Status: RESOLVED FIXED

(Core :: XPConnect, defect)

Description

[Jesse Ruderman]

My fuzzer created a situation where gc-heap-committed-unused is temporarily larger than gc-heap-allocated. This caused an assertion failure:

###!!! ASSERTION: Invalid value for js-main-runtime-gc-heap-committed-unused-ratio: 'false', file aboutMemory.js, line 0

    7,711,104 B ── js-main-runtime-gc-heap-allocated
    1,083,008 B ── js-main-runtime-gc-heap-arena-unused
    2,097,152 B ── js-main-runtime-gc-heap-chunk-clean-unused
    4,837,376 B ── js-main-runtime-gc-heap-chunk-dirty-unused
   15,728,640 B ── js-main-runtime-gc-heap-committed
    8,017,536 B ── js-main-runtime-gc-heap-committed-unused
        103.97% ── js-main-runtime-gc-heap-committed-unused-ratio [?!]
            0 B ── js-main-runtime-gc-heap-decommitted

Presumably a regression from http://hg.mozilla.org/mozilla-central/rev/f5a301fe9ba5. Bug 748440 comment 1 even anticipated the issue. Why was this reporter changed from a percentage to a ratio?

Comment 1

[Justin Lebar (not reading bugmail)]

> Why was this reporter changed from a percentage to a ratio?

For the purposes of telemetry, I thought the ratio was a more interesting measurement.

We should just get rid of this assertion.  I looked for it and couldn't find it, but I clearly didn't look hard enough.

Comment 2

[Justin Lebar (not reading bugmail)]

Attachment: Patch v1

Comment 3

[Ed Morley [:emorley]]

Landed as:
https://hg.mozilla.org/integration/mozilla-inbound/rev/c1243d1fb401

However turned test_aboutmemory.xul permaorange on OS X, so backed out:
https://tbpl.mozilla.org/?tree=Mozilla-Inbound&rev=c1243d1fb401
https://tbpl.mozilla.org/php/getParsedLog.php?id=11472251&tree=Mozilla-Inbound

https://hg.mozilla.org/integration/mozilla-inbound/rev/05d1ae4caf36

Comment 4

[Justin Lebar (not reading bugmail)]

And landed again with a test fix.  https://hg.mozilla.org/integration/mozilla-inbound/rev/0528b55a2616

Comment 5

[:Ms2ger (he/him; ⌚ UTC+1/+2)]

https://hg.mozilla.org/mozilla-central/rev/c1243d1fb401
https://hg.mozilla.org/mozilla-central/rev/05d1ae4caf36
https://hg.mozilla.org/mozilla-central/rev/0528b55a2616