698953 - Zero "heap-allocated" value leading to bogus values (including negative "heap-unclassified") in about:memory (MacOS 10.7 with --disable-jemalloc)

Status: RESOLVED WORKSFORME

(Toolkit :: about:memory, defect)

Description

[Nicholas Nethercote [inactive]]

In bug 683106, Trevor saw this:

  OSX 10.7.2 x86_64 rev/04b4ea333800

  21,939,504 B (100.0%) -- explicit
  ├──522,557,384 B (2381.81%) -- layout
  │  ├──520,972,208 B (2374.59%) -- shell(tables.php.html)

  ├──334,171,529 B (1523.15%) -- dom
  ├──24,031,584 B (109.54%) -- js

  └──-869,789,110 B (-3964.49%) -- heap-unclassified

In bug 696761, Limi saw this:

  690.16 MB (100.0%) -- explicit
  ├──832.62 MB (120.64%) -- js
  │  ├──238.87 MB (34.61%) -- gc-heap-chunk-dirty-unused
  │  ├──110.50 MB (16.01%) -- compartment([System Principal], 0x1009fe400)

and his heap-unclassified was negative.

In both cases, the "explicit" number is way too low.  Something's going wrong.  To have a chance to diagnose it we'll need (a) full output of about:memory?verbose in one of the bogus cases, and possibly also (b) steps to reproduce.

The common factor is that both Trevor and Limi are using MacOS 10.7.

Comment 1

[Justin Lebar (not reading bugmail)]

We're going to turn on jemalloc for 10.7 Real Soon Now, so this might just fix itself.

Comment 2

[Reuben Morais [:reuben]]

Attachment: about:memory?verbose output

On Mozilla/5.0 (Macintosh; Intel Mac OS X 10.7; rv:10.0a1) Gecko/20111101 Firefox/10.0a1.

Comment 3

[Nicholas Nethercote [inactive]]

Here's the problem:

  0 B -- heap-allocated

All the other bogus values are derived from that.

Sounds like the 10.7 jemalloc turn-on will fix this then.  In the meantime, if we change GetHeapAllocated() and GetHeapUnallocated() to return -1 (meaning "unknown") then about:memory should degrade gracefully.

Comment 4

[Nicholas Nethercote [inactive]]

Judging from bug 694896, the preferred way to detect 10.7 is something like this?

  malloc_zone_t *default_zone = malloc_default_zone();
  bool isLion = (default_zone->version == LION_MALLOC_ZONE_T_VERSION);

We should probably do this even though jemalloc will be landing soon, since you can build with --disable-jemalloc.

Comment 5

[Nicholas Nethercote [inactive]]

nsToolkit::OnLionOrLater() is probably easier!

Comment 6

[Alex Limi (:limi) — Firefox UX Team]

Attachment: about:memory output from my setup (slightly redacted)

Comment 7

[Nicholas Nethercote [inactive]]

Limi has the same problem.

Comment 8

[Trevor Benedict]

Attachment: about:memory verbose

rev/67d1049b0bf9
./Nightly.app/Contents/MacOS/firefox-bin -safe-mode -new-tab ./tables.php.html

Comment 9

[Trevor Benedict]

Attachment: FF29 memory report

I guess I should update this with a new report.
Thanks for all the hard work Nicholas.

Build identifier: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:29.0) Gecko/20100101 Firefox/29.0

Comment 10

[Nicholas Nethercote [inactive]]

This bug is no longer serving a useful purpose.