Why is Chromium running all tabs in a single process?
Typically, Chromium will group n tabs together into a single OS process, where n is typically a small number.
However, for one of my Chromium profiles, all of my currently open tabs appear to be in the same process. To be exact, there are 43 tabs currently open in this profile, across two windows. All 43 tabs are listed by the Chromium task manager as being in one process. (PID = 14530.)
If I ps that process, I see:
/usr/lib64/chromium-browser/chrome --type=renderer --lang=en-US --force-fieldtrials=ForceCompositingMode/disable/InfiniteCache/No/Prefetch/ContentPrefetchPrefetchOn/Prerender/Prerender15minTTL/PrerenderLocalPredictor/Enabled/UMA-New-Install-Uniformity-Trial/Experiment/UMA-Session-Randomized-Uniformity-Trial-5-Percent/default/UMA-Uniformity-Trial-1-Percent/group_36/UMA-Uniformity-Trial-10-Percent/group_04/UMA-Uniformity-Trial-20-Percent/group_02/UMA-Uniformity-Trial-5-Percent/group_18/UMA-Uniformity-Trial-50-Percent/group_01/ --disable-gl-multisampling --disable-accelerated-2d-canvas --disable-accelerated-video-decode --channel=12624.99.622289786
I understand that there are a few command line flags to alter how Chromium groups tabs into processes, however, I am not passing any of those. (I did not know they existed before today, while Googling for the answer to this question.)
I have two other profiles — the affected profile is a "sort-of-work" profile, I also have "normal" and "sites-that-really-love-cookies" — the other two profiles ("normal" and "cookies") are acting normally.
Two things I've tried:
- Restarting Chromium. Chromium restored all the tabs into a single process.
- Closing and re-opening tabs. Typically, one can hit Ctrl+W, Ctrl+Shift+T to coerce Chrome to relocate a tab to a different process. (Though sometimes it does choose the process you're trying to kill, not always. This is useful to kill off a Chromium process that is leaking memory for some reason.) In this case, Chromium appears to always choose the 43-tab mega-process to re-open the tab in.
I am running Chromium v29.0.1547.57 on Gentoo.
The Google Chromium developer documentation specifies that there are three different ways that Chrome or Chromium can launch processes.
Many people may not know this, but the Chrome/Chromium developers do split tests on users (called "Field Trials"), where different options will be chosen for you and your group of users.
It could be that you are in a Field Trial to check what the performance impact is between different types of process models (http://www.chromium.org/developers/design-documents/process-models)