Temporary add-on files created by ProductAddonChecker are not always deleted. $ ls tmpaddon*|wc -l 15 $ python -m ffpuppet -P ffprof_i0cp1m3p m-c-1501226576-asan-opt/firefox [2017-07-28 10:09:57] Running Firefox (pid: 20845)... [2017-07-28 10:10:03] Firefox process closed $ ls tmpaddon*|wc -l 16 $ python -m ffpuppet -P ffprof_i0cp1m3p m-c-1501226576-asan-opt/firefox [2017-07-28 10:10:13] Running Firefox (pid: 20962)... [2017-07-28 10:10:20] Firefox process closed $ ls tmpaddon*|wc -l 17 In both cases above, I allowed Firefox to launch to a new tab and then closed it immediately with Ctrl+W. I also reproduced this by creating two new profiles through the profile manager. After several launches in each profile I had two new tmpaddon files in /tmp. This is especially problematic for fuzzing where each run uses a new profile, and these files are consuming /tmp space on test instances. File details: Path = /tmp/tmpaddon Type = zip Physical Size = 515722 Date Time Attr Size Compressed Name ------------------- ----- ------------ ------------ ------------------------ 2016-07-29 15:28:58 ..... 1373839 515281 libgmpopenh264.so 2016-07-29 15:28:29 ..... 116 97 gmpopenh264.info ------------------- ----- ------------ ------------ ------------------------ 1373955 515378 2 files, 0 folders $ md5sum /tmp/tmpaddon* d75247cd502f01a8c072e723e63e18b9 /tmp/tmpaddon d75247cd502f01a8c072e723e63e18b9 /tmp/tmpaddon-1683b d75247cd502f01a8c072e723e63e18b9 /tmp/tmpaddon-3d13ed d75247cd502f01a8c072e723e63e18b9 /tmp/tmpaddon-7575c9 ...

The launcher I used is available here: https://github.com/MozillaSecurity/ffpuppet (pip install git+https://github.com/MozillaSecurity/ffpuppet) Although not required to reproduce, by default it creates an empty profile for each launch, which exacerbates the issue.