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According to Multiprocess Firefox on MDN, Firefox 57 finally runs things in different processes.

So is Firefox 57 multithreaded?

In particular, how many cores does it use at most? Say I open 20 tabs at once on a quad-core machine, will Firefox 57 launch as many threads, or at least as many as needed to max out my CPU?

(Chromium for instance spawns a number of sub-processes and very easily uses all the resources available. Firefox up to 56 in GNU/Linux is rarely seen going over 135 % of one core however many tabs I open.)

Nemo
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  • It uses as many cores as your system has. 135% of a code that must be a typo – Ramhound Nov 18 '17 at 14:16
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    @Ramhound not really - both Linux and Mac OS report a single core as 100%, so 135% utilisation is for example 100% of one core and 35% of another. – jaskij Nov 18 '17 at 15:07
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    Currently using 7 processes on my octa-core system... running 4 instances of http://browserbench.org/ARES-6 uses about 45-50% of the system (and causes the browser to lag a bit), so it uses 3-4 cores. – Mokubai Nov 18 '17 at 15:31

1 Answers1

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Is Firefox 57 multithreaded?

Yes, and it is configurable as well.

You may see 3 or more processes running in the Task Manager

  • one process for the main Firefox window (user interface)
  • one or more processes for content threads set via "Options/Preferences -> General -> Performance" (dom.ipc.processCount), default in 57 is 4.
  • one process for the compositor thread (Windows)
  • one process for Quantum CSS (Stylo)

Source Why is Firefox Quantum running 7 instances?

Further Reading

DavidPostill
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