Public bug reported: When Firefox is open, and I open Chromium, many features of Firefox fail to work for several seconds. (To reproduce, start with neither Firefox nor Chromium open; open Firefox, and allow one or more web pages to load; then open Chromium; the issue starts a second or two after Chromium is opened.) This is a temporary issue, lasting for several seconds; the length of time it lasts appears to depend on how many open tabs have been viewed since Firefox opened (on my computer, around 10 seconds with 1 tab having been viewed, around a minute with 10 tabs having been viewed). This reproduces even when running Firefox as `firefox -safe-mode`.
While the issue is ongoing (i.e. starting around a second after Chromium is open, and persisting for typically tens of seconds), some features of Firefox work, but most do not: - Scrolling the current tab short distances succeeds, showing the expected text on the page. - Scrolling the current tab long distances (several screeenfuls) causes the page to be "cut off" past a certain point, with only a blank background rendering. - Moving the mouse cursor over a link does not change the mouse cursor (expected behaviour, and behaviour while the issue is not ongoing, is for it to change to a hand shape). - Changing tab causes the resulting page not to display: rather, a grey background is displayed, and sometimes a loading spinner. - Changing tab back then causes the original page not to render, as if it were new, despite the fact it was correctly displayed earlier. - The address bar functions as normal; the issue does not appear to affect address bar functionality. Additionally, while the issue is ongoing, Firefox uses 100% CPU. At some point after the issue in question starts, it stops, and all Firefox features return to normal (including any missing or incorrectly rendered page content, which renders again when the issue ends). The trigger is specifically the act of opening Chromium: Firefox can function just fine once the issue ends, even if Chromium is still open, and functions just fine if Chromium is opened first. I have an (unconfirmed) theory that opening Chromium is causing some operation within Firefox to become very slow, using up all the CPU time, and the other observed misbehaviours within Firefox are a consequence of how slowly it is running; however, I've listed them all anyway in case it provides clarity into what the specific nature of the bug is. ProblemType: Bug DistroRelease: Ubuntu 18.04 Package: firefox 71.0+build5-0ubuntu0.18.04.1 ProcVersionSignature: Ubuntu 5.0.0-37.40~18.04.1-generic 5.0.21 Uname: Linux 5.0.0-37-generic x86_64 AddonCompatCheckDisabled: False ApportVersion: 2.20.9-0ubuntu7.9 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: ais523 1800 F.... pulseaudio BuildID: 20191205184924 Channel: Unavailable CurrentDesktop: X-Cinnamon Date: Tue Dec 17 00:29:10 2019 ExecutablePath: /usr/lib/firefox/firefox ForcedLayersAccel: False IfupdownConfig: # interfaces(5) file used by ifup(8) and ifdown(8) auto lo iface lo inet loopback IncompatibleExtensions: English (South Africa) Language Pack - langpack-en...@firefox.mozilla.org Français Language Pack - langpack...@firefox.mozilla.org English (GB) Language Pack - langpack-en...@firefox.mozilla.org Default - {972ce4c6-7e08-4474-a285-3208198ce6fd} InstallationDate: Installed on 2019-11-11 (35 days ago) InstallationMedia: Ubuntu 18.04.3 LTS "Bionic Beaver" - Release amd64 (20190805) IpRoute: default via 192.168.1.1 dev wlp2s0 proto dhcp metric 600 169.254.0.0/16 dev wlp2s0 scope link metric 1000 192.168.1.0/24 dev wlp2s0 proto kernel scope link src 192.168.1.101 metric 600 MostRecentCrashID: bp-935fd166-3720-454f-8fe5-0a1752140227 PrefErrors: Unexpected character ',' before close parenthesis @ /usr/lib/firefox/omni.ja:greprefs.js:722 PrefSources: prefs.js ProcEnviron: LANGUAGE=en_GB:en PATH=(custom, user) XDG_RUNTIME_DIR=<set> LANG=en_GB.UTF-8 SHELL=/bin/bash Profiles: Profile0 (Default) - LastVersion=71.0/20191205184924 (In use) RunningIncompatibleAddons: True SourcePackage: firefox UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 05/30/2019 dmi.bios.vendor: Dell Inc. dmi.bios.version: 1.5.1 dmi.board.name: 0DDKKC dmi.board.vendor: Dell Inc. dmi.board.version: A00 dmi.chassis.type: 10 dmi.chassis.vendor: Dell Inc. dmi.modalias: dmi:bvnDellInc.:bvr1.5.1:bd05/30/2019:svnDellInc.:pnInspiron3583:pvr:rvnDellInc.:rn0DDKKC:rvrA00:cvnDellInc.:ct10:cvr: dmi.product.family: Inspiron dmi.product.name: Inspiron 3583 dmi.product.sku: 08CA dmi.sys.vendor: Dell Inc. ** Affects: firefox (Ubuntu) Importance: Undecided Status: New ** Tags: amd64 apport-bug bionic -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1856624 Title: Firefox freezes temporarily at 100% CPU when Chromium is opened To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1856624/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs