[Bug 1031750] [NEW] XHR connections aren't closed properly

Björn Tillenius bjorn at canonical.com
Wed Aug 1 12:34:19 UTC 2012

Public bug reported:

In Firefox 14, when I abort an XHR connection, it seems like the
connection doesn't get closed properly at the system level, or at least
not as quickly as before. Firebug shows the connection as aborted, but
the actual network connection seems to still be open.

I'm attaching a sample web server that keeps the connection open (like a
long poll request) and a sample HTML file that creates XHR connections
and aborts them after a seconds. Using lsof (lsof -i | grep localhost |
grep firefox | wc --line) I can see that the number of connections just
keeps growing, until Firefox's connection limit is reached.

This causes a problem for automatic testing, which quickly navigates
through different pages. Since each page opens up a new connection that
doesn't get closed, we run into a situation where the tests starts
failing, since it can't connect to the server anymore.

I started seeing this behavior in Firefox 14 (Ubuntu version
14.0.1+build1-0ubuntu0.12.04.1) and I see it 14.0.1 downloaded from
mozilla.org as well. If I downgrade to Firefox 11 (Ubuntu version
11.0+build1-0ubuntu4) the number of open connections stay at 1 when
running the attached test scripts.

To reproduce the problem, run "python long_poll.py" to start a web
server. Then open abort_request.html in Firefox, which will open an XHR
connection and abort it once every second. While abort_request.html is
running look at the output of "lsof -i | grep localhost | grep firefox |
wc --line". In Firefox 11 it stays around 1 and in Firefox 14 it goes up
to 15, which is my configured connection limit (network.http.max-

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: firefox 14.0.1+build1-0ubuntu0.12.04.1
ProcVersionSignature: Ubuntu 3.2.0-27.43-generic 3.2.21
Uname: Linux 3.2.0-27-generic x86_64
AddonCompatCheckDisabled: False
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.24.
 **** List of PLAYBACK Hardware Devices ****
 card 0: Intel [HDA Intel], device 0: CONEXANT Analog [CONEXANT Analog]
   Subdevices: 1/1
   Subdevice #0: subdevice #0
ApportVersion: 2.0.1-0ubuntu11
Architecture: amd64
 **** List of CAPTURE Hardware Devices ****
 card 0: Intel [HDA Intel], device 0: CONEXANT Analog [CONEXANT Analog]
   Subdevices: 1/1
   Subdevice #0: subdevice #0
 /dev/snd/controlC0:  bjorn      3512 F.... pulseaudio
BuildID: 20120713224749
 Card hw:0 'Intel'/'HDA Intel at 0xf2620000 irq 48'
   Mixer name	: 'Conexant CX20561 (Hermosa)'
   Components	: 'HDA:14f15051,17aa20ff,00100000'
   Controls      : 21
   Simple ctrls  : 13
 Card hw:29 'ThinkPadEC'/'ThinkPad Console Audio Control at EC reg 0x30, fw 7XHT21WW-1.03'
   Mixer name	: 'ThinkPad EC 7XHT21WW-1.03'
   Components	: ''
   Controls      : 1
   Simple ctrls  : 1
 Simple mixer control 'Console',0
   Capabilities: pswitch pswitch-joined penum
   Playback channels: Mono
   Mono: Playback [on]
Channel: Unavailable
Date: Wed Aug  1 15:18:25 2012
ForcedLayersAccel: False
PrefSources: prefs.js
 PATH=(custom, user)
Profiles: Profile0 (Default) - LastVersion=11.0/20120410121533 (Out of date)
 rhythmbox-mozilla 2.96-0ubuntu4.1
 totem-mozilla     3.0.1-0ubuntu21
 sun-java6-bin     6.26-1oneiric1
RunningIncompatibleAddons: False
SourcePackage: firefox
UpgradeStatus: Upgraded to precise on 2011-12-16 (229 days ago)
 pcm.btheadset {
         type bluetooth
         device 00:0D:3C:6B:34:39
         profile "auto"
dmi.bios.date: 12/19/2008
dmi.bios.vendor: LENOVO
dmi.bios.version: 6DET38WW (2.02 )
dmi.board.name: 74695RG
dmi.board.vendor: LENOVO
dmi.board.version: Not Available
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: Not Available
dmi.modalias: dmi:bvnLENOVO:bvr6DET38WW(2.02):bd12/19/2008:svnLENOVO:pn74695RG:pvrThinkPadX200s:rvnLENOVO:rn74695RG:rvrNotAvailable:cvnLENOVO:ct10:cvrNotAvailable:
dmi.product.name: 74695RG
dmi.product.version: ThinkPad X200s
dmi.sys.vendor: LENOVO

** Affects: firefox (Ubuntu)
     Importance: Undecided
         Status: New

** Tags: amd64 apport-bug precise running-unity

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