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Firefox 50 creates new process for current tab

Omega13
Omega13
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Since Firefox 50 was installed on one of my machines (only one), it is opening two firefox.exe processes when I browse. Process Explorer shows that one of the processes was opened as a sub-process of the main firefox.exe. If I terminate the main process, Firefox closes and the second process disappears shortly thereafter, as expected. If I kill the sub-process, my current tab shows 'Bad News, this tab has crashed'. So, it looks like the sub-process just controls the current tab. What setting controls this behavior, and why has this happened only on one of the three machines I currently have Firefox 50 installed on (the others only have the one normal firefox.exe running)?

Since Firefox 50 was installed on one of my machines (only one), it is opening two firefox.exe processes when I browse. Process Explorer shows that one of the processes was opened as a sub-process of the main firefox.exe. If I terminate the main process, Firefox closes and the second process disappears shortly thereafter, as expected. If I kill the sub-process, my current tab shows 'Bad News, this tab has crashed'. So, it looks like the sub-process just controls the current tab. What setting controls this behavior, and why has this happened only on one of the three machines I currently have Firefox 50 installed on (the others only have the one normal firefox.exe running)?

All Replies (3)

philipp
philipp
  • Moderator
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hi Omega13, what you are seeing is the new multi-process architecture (codename "e10s") in action, which should lead to increased stability, security and performance in firefox the long run. in firefox 50 e10s got enabled for all users whose addons claim that they are compatible with e10s: https://blog.mozilla.org/futurereleases/2016/08/02/whats-next-for-multi-process-firefox/

tmwellington
tmwellington
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One of the two processes is doing a *lot* of I/O Read bytes according to Task Manager. This does not seem to be any sort of performance enhancement on an older 32bit machine with limited hard drive space. Can we opt out of this "enhancement?"

jscher2000 - Support Volunteer
jscher2000 - Support Volunteer
  • Top 10 Contributor
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Multiprocess (e10s)

One of the headline changes in Firefox 48+ is e10s, which separates the browser interface process from the page content process. More and more users are gradually having this multiprocess feature switched on. The performance impact of this can vary a lot between systems: many users find it faster, some find it slower, for many it's neutral. There probably is somewhat more memory use than when everything runs in a single firefox.exe process. However, I don't see why there would be a different level of disk I/O...

Are you using e10s?

You can confirm you have this feature turned on as follows. Either:

  • "3-bar" menu button > "?" button > Troubleshooting Information
  • (menu bar) Help > Troubleshooting Information
  • type or paste about:support in the address bar and press Enter

In the first table on the page, check the row for "Multiprocess Windows" and see whether the number on the left side of the fraction is greater than zero. If so, you are using e10s.

If you are using e10s:

If you think Firefox is not performing well or is using an unreasonable amount of resources now, you could evaluate whether e10s is causing this problem by turning it off as follows:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button promising to be careful.

(2) In the search box above the list, type or paste autos and pause while the list is filtered

(3) Double-click the browser.tabs.remote.autostart.2 preference to switch the value from true to false

Note: the exact name of the preference may vary, but it will start with browser.tabs.remote.autostart

At your next Firefox startup, it should run in the traditional way. Any difference?