How to analyse 100% CPU by firefox?

Add-ons Development
#1

Hello
My firefox (94 on macos) is eating 100% and I would like to analyse the root cause that may be due to my extension SendTopQNAP.

I already inspected about:performance tab which shows no very low CPU usage for my extension and same for others.

How to analyse what goes wrong with my firefox ?

On command line process if following:

501 37472 37466 4004 0 46 0 7117544 226104 - R 0 ?? 419:29.15 /Applications/Firefox.app/Contents/MacOS/plugin-container.app/Contents/MacOS/plugin-container -childID 2 -isForBrowser -prefsLen 4763 -prefMapSize 273012 -jsInit 278680 -sbStartup -sbAppPath /Applications/Firefox.app -sbLevel 3 -sbAllowAudio -sbAllowWindowServer -parentBuildID 20211103134640 -appdir /Applications/Firefox.app/Contents/Resources/browser -profile /Users/fredericwolff/Library/Application Support/Firefox/Profiles/qpw0l296.default-release 37466 gecko-crash-server-pipe.37466 org.mozilla.machname.1372284212 tab

and pstree :
-+= 37466 fredericwolff /Applications/Firefox.app/Contents/MacOS/firefox
|— 37467 fredericwolff /Applications/Firefox.app/Contents/MacOS/plugin-container.app/Contents/MacOS/plugin-container -childID 1 -isForBrowser -prefsLen 1 -prefMapSize 273012 -jsInit 278680 -sbStartup -sbAppPath /Applications/Firefox.app -sbLevel 3 -sbAllowAudio -sbAllowWindowServer -parentBuildID 20211103134640 -appdir /Applications/Firefox.app/Cont
|— 37472 fredericwolff /Applications/Firefox.app/Contents/MacOS/plugin-container.app/Contents/MacOS/plugin-container -childID 2 -isForBrowser -prefsLen 4763 -prefMapSize 273012 -jsInit 278680 -sbStartup -sbAppPath /Applications/Firefox.app -sbLevel 3 -sbAllowAudio -sbAllowWindowServer -parentBuildID 20211103134640 -appdir /Applications/Firefox.app/C
|— 37476 fredericwolff /Applications/Firefox.app/Contents/MacOS/plugin-container.app/Contents/MacOS/plugin-container -parentBuildID 20211103134640 -prefsLen 5793 -prefMapSize 273012 -sbStartup -sbAppPath /Applications/Firefox.app -appdir /Applications/Firefox.app/Contents/Resources/browser -profile /Users/fredericwolff/Library/Application Support/Fi
|— 37601 fredericwolff /Applications/Firefox.app/Contents/MacOS/plugin-container.app/Contents/MacOS/plugin-container -parentBuildID 20211103134640 -prefsLen 8684 -prefMapSize 273012 -sbStartup -sbAppPath /Applications/Firefox.app -appdir /Applications/Firefox.app/Contents/Resources/browser -profile /Users/fredericwolff/Library/Application Support/Fi
|— 51144 fredericwolff /Applications/Firefox.app/Contents/MacOS/plugin-container.app/Contents/MacOS/plugin-container -childID 134 -isForBrowser -prefsLen 15775 -prefMapSize 273012 -jsInit 278680 -sbStartup -sbAppPath /Applications/Firefox.app -sbLevel 3 -sbAllowAudio -sbAllowWindowServer -parentBuildID 20211103134640 -appdir /Applications/Firefox.ap
— 51420 fredericwolff /Applications/Firefox.app/Contents/MacOS/plugin-container.app/Contents/MacOS/plugin-container -childID 141 -isForBrowser -prefsLen 15776 -prefMapSize 273012 -jsInit 278680 -sbStartup -sbAppPath /Applications/Firefox.app -sbLevel 3 -sbAllowAudio -sbAllowWindowServer -parentBuildID 20211103134640 -appdir /Applications/Firefox.ap

#2

In the browser toolbox you can record performance profiles. You might have to show the “Performance” developer tool in the dev tools settings.

#3

Maybe it’s related to this:


The fix is coming in Firefox 95, scheduled for 2021-12-07.

Open about:processes to see if extension process it taking all the CPU.

#4

Thanks for your help.

webextension is indeed the one consuming 100% CPU
Let’s wait for next FF then.