This is what I gathered so far.
Couple of days ago I ran out of memory again, but logs are so filled with that annoying
[0x7f0e6bfff700] ERROR - Couldn't get size of file "/usr/lib/plexmediaserver/Resources/Plug-ins-ab5e1197c/WebClient.bundle/Contents/Resources": boost::filesystem::file_size: Operation not permitted: "/usr/lib/plexmediaserver/Resources/Plug-ins-ab5e1197c/WebClient.bundle/Contents/Resources"
[0x7f0e6bfff700] DEBUG - Content-Length of /usr/lib/plexmediaserver/Resources/Plug-ins-ab5e1197c/WebClient.bundle/Contents/Resources is 0 (of total: 0).
that all 6 log files span only last 15 hours and naturally it takes more like a week for me to start seeing OOM events. But, I managed to get to same amounts of used memory in ~10 minutes manually by simply opeing page of each movie and returning back to library page in app.plex.tv.
And this test was performed with the second PMS instance stopped, so it is not related. Network namespaces or any other means of isolation are not used with the main one, it is a basic install from your PPA. So, it seems that video transcode is what triggered OOM events as it requires large amounts of RAM which OS does not have to spare by the time leak gets it critical mass. But the leak itself relates to something like creating thumbnails or refreshing metadata as these are the obvious tasks performed on request of each media’s page.
Here are the logs, showing ‘Plex Media Server’ process going from 50mb usage after restart to ~970mb in minutes:
https://drive.google.com/drive/folders/1PqpQ_58rNLOIsTv32ypYkz7IB6Gxy0PF
Hour later usage is still at 925MB.
UPD: Leak was fixed:
