573631 - trace malloc for x86_64 Mac OS X builds is too slow

Status: RESOLVED FIXED

(Core :: XPCOM, defect)

Description

[Josh Aas]

I believe the cause for bug 558496 is that trace malloc runs incredibly slowly on x86_64 Mac OS X builds. The slowdown appears to be worse than 10x, possibly 20x or so, leading to the 3600 second timeout. I can reproduce this behavior locally on a Mac Pro, and the problem goes away on my machine and the Mac Mini build slave if I run tests without trace malloc.

Comment 1

[Josh Aas]

Attachment: sample 1, app startup

This sample was taken during app startup and as expected, 'findClosestSymbol' dominates.

Comment 2

[Josh Aas]

Attachment: sample 2, network load

This sample was taken during the first network load, after:

localhost - - [21/Jun/2010 20:01:08] "GET /bloatcycle.html HTTP/1.1" 200 -

Comment 3

[Josh Aas]

Attachment: sample 2, network load, expanded

Same as sample 2 but with the stack expanded.

Comment 4

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Is findClosestSymbol called from within dladdr?

Comment 5

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

So one possibility here is that the calltree locking is much too fine-grained; I think I've been concerned about that in the past.

Comment 6

[Josh Aas]

(In reply to comment #4)
> Is findClosestSymbol called from within dladdr?

Yes:

dyld ImageLoaderMachOCompressed::findClosestSymbol(void const*, void const**) const
dyld dladdr
XUL NS_DescribeCodeAddress

Comment 7

[Armen [:armenzg]]

Anyone that can be working on this?

We are trying to move the 10.5 leak builds to be run on 10.6 minis in bug 674647 and we are hitting this problem.

Comment 8

[Rafael Ávila de Espíndola (:espindola) (not reading bugmail)]

I think this was fixed with bug 696281. Can someone check?

Comment 9

[Armen [:armenzg]]

We seemed to have fixed the slowness (few good runs showed only 1 minute on running alive_tests2) but we have resuscitated bug 558496.

Comment 10

[Rafael Ávila de Espíndola (:espindola) (not reading bugmail)]

This was fixed in https://hg.mozilla.org/mozilla-central/rev/c9a74f4ee1f7