Electrolysis/Multiple content processes

Overview

After e10s is enabled for all users, the next step is to introduce multiple content processes. The goal is to bring out the most from the multi process architecture we introduced with e10s, gain performance where it's possible and minimize the impact of content process crashes. The challenge is to achieve this without sacrificing the advantage we currently have in memory usage compared to our competitors.

One explicit non-goal of this project is to nest content processes for e.g. iframes. There is work underway to do that in bug 1277066 in parallel to this project.

Roadmap

TBD

Bug tracking

Triage

• Triage list ('e10s-multi:?' in whiteboard)

Priorities

• P1
• P2
• P3

Initial Rollout (completed 8/1/2017)

Release Criteria

• Crash Rates need to be low enough that they have little, if any perceivable impact to the overall crash rates. See the crash rates starting with Firefox 54 Beta, here.
• Performance metrics including memory-based metrics are in the release criteria wiki page
• We may need to activate e10s-multi based on physical RAM size depending how the number of content processes impacts such memory. We have a hypothesis for both cases (increased number of content process will either benefit systems with lower RAM or make things worse).

Release Plan

• e10s-multi was enabled with 4 processes in Firefox 55 Nightly and currently beta experiments are being conducted in Firefox 54. Read more about the experiments, here.

Memory management

• Memory cost of a content process - relatively high
• Memory usage of e10s compared to other browsers - we're not the worst offender
• Extending Nuwa for all platform does not seem realistic, and since the most memory overhead comes from JS, we should address the problem at JS engine level first. Till Schneidereit suggested lazy cross-process memory sharing.

Testing

• Currently for bc/dt tests we keep content processes alive to fight timeouts
• Areas where additional testing is needed have to be identified.
• Some tests were disabled, re-enabling them is high priority work currently

Process startup time

• Improve content process startup time

Links

• Process Model (2012)
• Recent dev.platform discussion

Teams

TBD