669739 - Loading bugzilla main page then closing the tab doesn't decrease memory used

Status: RESOLVED INCOMPLETE

(Core :: General, defect)

Description

[Justin Lebar (not reading bugmail)]

This is in the spirit of "browse around for a while, then close all tabs.  Firefox holds onto lots of memory."  We discussed this kind of bug at yesterday's MemShrink meeting.

I thought I'd start small.  On my Linux x86-64 machine, I measured memory used immediately after startup, after loading bmo (not logged in), and after closing the tab and clicking minimize memory usage.  I'll attach the full results, but in summary:

* Initial

  RSS: 66m
  Explicit: 39m

* After loading http://bugzilla.mozilla.org

  RSS: 83m
  Explicit: 50m

* After closing tab, clicking minimize memory usage:

  RSS: 85m
  Explicit: 56m

khuey's suggested technique is to use trace-malloc and diffbloatdump to see where this memory is coming from and going to.

Comment 1

[Ed Morley [:emorley]]

Was this with bugzilla-tweaks installed? Even after the resolution of bug 639626, it still causes leaks from what I've found. (Meant to file something earlier this week).

Comment 2

[Justin Lebar (not reading bugmail)]

Attachment: about:memory?verbose before, during, after

These measurements were taken from safe mode.

Comment 3

[Nicholas Nethercote [inactive]]

Generating about:memory causes |explicit| to jump by up to 1.5MB on my Linux64 machine.  

So the 50MB to 56MB jump in comment 0 is suspicious.  But we don't have detailed data for that.

In contrast, the jump in the attachment (for which we do have detailed data) is from 56.8MB to 57.1MB, which isn't suspicious at all.

Comment 4

[Justin Lebar (not reading bugmail)]

What if I retitled this bug "closing bugzilla main page doesn't decrease memory used"?  Clearly opening it causes an increase in memory; we don't understand why it doesn't all go away when you close the tab.

Comment 5

[Andrew McCreight [:mccr8]]

This is kind of a vague bug so let's close it.