1172365 - Firefox consuming 20% CPU while in background

Status: RESOLVED WORKSFORME

(Core :: General, defect)

Description

[Jonathan Guerin]

Attachment: Sample of Firefox (Safe Mode - Seconds).txt

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:39.0) Gecko/20100101 Firefox/39.0
Build ID: 20150601171003

Steps to reproduce:

Let Firefox load all tabs, then monitor CPU usage while in background, even when in Safe Mode.


Actual results:

Firefox uses 20% CPU in background on a dual-core MacBook Pro, and 50-60% when in foreground. This is in Safe Mode.


Expected results:

The same tabs open with Firefox in background on my Windows PC shows <1% CPU usage.

Comment 1

[Jonathan Guerin]

Application Basics
------------------

Name: Firefox
Version: 39.0
Build ID: 20150601171003
Update Channel: beta
User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:39.0) Gecko/20100101 Firefox/39.0
Multiprocess Windows: 0/1 (default: false)

Crash Reports for the Last 3 Days
---------------------------------

All Crash Reports

Extensions
----------

Name: 1Password
Version: 4.4.0.b7
Enabled: false
ID: [e-mail]

Name: Adblock Plus
Version: 2.6.9.1-signed
Enabled: false
ID: {d10d0bf8-f5b5-c8b4-a8b2-2b9879e08c5d}

Name: DownThemAll!
Version: 2.0.18.1-signed
Enabled: false
ID: {DDC359D1-844A-42a7-9AA1-88A850A938A8}

Name: Firebug
Version: 2.0.10
Enabled: false
ID: [e-mail]

Name: Gecko Profiler
Version: 1.16.1
Enabled: false
ID: jid0-edalmuivkozlouyij0lpdx548bc@jetpack

Graphics
--------

Asynchronous Pan/Zoom: none
Device ID: 0x a2e
GPU Accelerated Windows: 0/1 Basic (OMTC)
Vendor ID: 0x8086
WebGL Renderer: Intel Inc. -- Intel Iris OpenGL Engine
windowLayerManagerRemote: true
AzureCanvasBackend: quartz
AzureContentBackend: quartz
AzureFallbackCanvasBackend: none
AzureSkiaAccelerated: 0

Important Modified Preferences
------------------------------

accessibility.typeaheadfind.flashBar: 0
browser.cache.disk.capacity: 358400
browser.cache.disk.filesystem_reported: 1
browser.cache.disk.smart_size_cached_value: 358400
browser.cache.disk.smart_size.first_run: false
browser.cache.disk.smart_size.use_old_max: false
browser.cache.frecency_experiment: 3
browser.download.importedFromSqlite: true
browser.places.smartBookmarksVersion: 7
browser.sessionstore.upgradeBackup.latestBuildID: 20150601171003
browser.startup.homepage: about:newtab
browser.startup.homepage_override.buildID: 20150601171003
browser.startup.homepage_override.mstone: 39.0
browser.tabs.loadBookmarksInBackground: true
browser.tabs.loadDivertedInBackground: true
browser.tabs.maxOpenBeforeWarn: 100
dom.mozApps.used: true
extensions.lastAppVersion: 39.0
font.internaluseonly.changed: true
media.gmp-gmpopenh264.enabled: true
media.gmp-gmpopenh264.lastUpdate: 1432101629
media.gmp-gmpopenh264.path: /Users/jguerin/Library/Application Support/Firefox/Profiles/05tbo3h1.default-1404877435981/gmp-gmpopenh264
media.gmp-gmpopenh264.version: 1.4
media.gmp-manager.buildID: 20150601171003
media.gmp-manager.lastCheck: 1433715051
network.cookie.prefsMigrated: true
network.predictor.cleaned-up: true
places.database.lastMaintenance: 1433712785
places.history.expiration.transient_current_max_pages: 104858
plugin.disable_full_page_plugin_for_types: application/pdf
plugin.importedState: true
plugin.state.default browser: 0
plugin.state.flash: 1
plugin.state.java: 0
plugin.state.lwaplugin: 1
plugin.state.quicktime plugin: 1
print.print_bgcolor: false
print.print_bgimages: false
print.print_colorspace:
print.print_command:
print.print_downloadfonts: false
print.print_duplex: 1515870810
print.print_evenpages: true
print.print_in_color: true
print.print_margin_bottom: 0.5
print.print_margin_left: 0.5
print.print_margin_right: 0.5
print.print_margin_top: 0.5
print.print_oddpages: true
print.print_orientation: 0
print.print_page_delay: 50
print.print_paper_data: 0
print.print_paper_height: 11.00
print.print_paper_name:
print.print_paper_size_type: 1
print.print_paper_size_unit: 0
print.print_paper_width: 8.50
print.print_plex_name:
print.print_resolution: 1515870810
print.print_resolution_name:
print.print_reversed: false
print.print_scaling: 1.00
print.print_shrink_to_fit: true
print.print_to_file: false
print.print_unwriteable_margin_bottom: 57
print.print_unwriteable_margin_left: 25
print.print_unwriteable_margin_right: 25
print.print_unwriteable_margin_top: 25
privacy.sanitize.migrateFx3Prefs: true
storage.vacuum.last.index: 1
storage.vacuum.last.places.sqlite: 1430887328

Important Locked Preferences
----------------------------

JavaScript
----------

Incremental GC: true

Accessibility
-------------

Activated: false
Prevent Accessibility: 0

Library Versions
----------------

NSPR
Expected minimum version: 4.10.8
Version in use: 4.10.8

NSS
Expected minimum version: 3.19.1 Basic ECC
Version in use: 3.19.1 Basic ECC

NSSSMIME
Expected minimum version: 3.19.1 Basic ECC
Version in use: 3.19.1 Basic ECC

NSSSSL
Expected minimum version: 3.19.1 Basic ECC
Version in use: 3.19.1 Basic ECC

NSSUTIL
Expected minimum version: 3.19.1
Version in use: 3.19.1

Experimental Features
---------------------

Comment 2

[Jonathan Guerin]

It seems to be stuck on mach_msg_trap: http://people.mozilla.org/~bgirard/cleopatra/#report=59372024b8a1c2a22aa513c9bd55209672f05877&selection=0,1,35

Comment 3

[Marco Bonardo [:mak]]

would you mind trying in safe mode if the cpu usage improves or it's still that bad?

https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode

I see that David is working on a related project in bug 508427, he might be a better triager than me for this report.

Comment 4

[David Teller [:Yoric] - still alive but not very active]

Actually, unless I'm mistaken, mach_msg_trap doesn't cost any CPU. It's just Firefox doing nothing and waiting for responses.

Are you running Nightly? If so, we have a page called about:performance that can tell you a bit more about what' using CPU. It's very much a WIP, but it could be useful.

Comment 5

[Jonathan Guerin]

That(In reply to Marco Bonardo [::mak] from comment #3)
> would you mind trying in safe mode if the cpu usage improves or it's still
> that bad?
> 
> https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-
> mode
> 
> I see that David is working on a related project in bug 508427, he might be
> a better triager than me for this report.

That process sample was from safe mode :)

Comment 6

[Jonathan Guerin]

(In reply to David Rajchenbach-Teller [:Yoric] (use "needinfo") from comment #4)
> Actually, unless I'm mistaken, mach_msg_trap doesn't cost any CPU. It's just
> Firefox doing nothing and waiting for responses.
> 
> Are you running Nightly? If so, we have a page called about:performance that
> can tell you a bit more about what' using CPU. It's very much a WIP, but it
> could be useful.

It seems to be better with Nightly, though now I'm seeing latent CPU usage on a process called 'kernel_task'. 

Here's the about:performance output:
Jank level	User (%)	System (%)	Cross-Process (%)	Activations	
2	77	7	0	14	<process>
2	13	1	0	73	[System Principal], jar:file:///Applications/FirefoxNightly.app/Contents/Resources/omni.ja!/components/DataReportingService.js
0	0	0	0	1	Adblock Plus
2	8	1	0	2	1Password
4	10	2	0	53	[System Principal], about:blank
8	3207	215	8	4478	about:performance
1	5	0	0	3	about:performance

Comment 7

[Jonathan Guerin]

Reading about kernel_task (http://apple.stackexchange.com/questions/37366/what-exactly-does-kernel-task-do), and knowing that Nightly is running multi-process seems to suggest that whatever was causing the issue in FF 39 is now exhibiting as kernel calls? FWIW, it does seem to settle down after a time, hovering around 6% usage.

Comment 8

[David Teller [:Yoric] - still alive but not very active]

The result of about:performance shows nothing worrying with add-ons.
Note that the line with Jank Level 8 should be labelled "Firefox". That's bug 1173524.

Comment 9

[David Teller [:Yoric] - still alive but not very active]

Also, afaict, kernel_task is not related to Firefox.

Comment 10

[Jonathan Guerin]

No worries. Want me to try anything else?

Comment 11

[Abe - QA (:Abe_LV)]

Hi Jonathan,
Thank for taking time on this issue.

Are you still getting this issue on the latest version ? My CPU usage is below 1%. Can you give more detail information about number of tabs, and  urls to be used in each tab. Thanks

Comment 12

[Jonathan Guerin]

Hi Abe, I am not. Thanks for checking in!