Electrolysis/Release Criteria/Slow Script: Difference between revisions

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(Update with reviewer field.)
(Add more info about current state.)
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Analysis was reviewed by: rvitillo
Analysis was reviewed by: rvitillo


Open questions: have we tested the metric to make sure it's working properly in e10s?
How slow script notice count works on non-e10s:
* '''nsGlobalWindow::ShowSlowScriptDialog''' accumulates the SLOW_SCRIPT_NOTICE_COUNT histogram (https://dxr.mozilla.org/mozilla-central/source/dom/base/nsGlobalWindow.cpp#10677)
 
How slow script notice count works on e10s:
* [CHILD] '''nsGlobalWindow::ShowSlowScriptDialog''' sends a slow script notification via '''ProcessHangMonitor::NotifySlowScript''' (https://dxr.mozilla.org/mozilla-central/source/dom/base/nsGlobalWindow.cpp#10652)
* [CHILD] '''HangMonitorChild::NotifySlowScript''' invokes '''HangMonitorChild::NotifySlowScriptAsync''' to send out the slow script notice (https://dxr.mozilla.org/mozilla-central/source/dom/ipc/ProcessHangMonitor.cpp#352)
* [CHILD] '''PProcessHangMonitorChild::SendHangEvidence''' invokes '''PProcessHangMonitorParent::OnMessageReceived''' via IPC (https://dxr.mozilla.org/mozilla-central/source/obj-x86_64-unknown-linux-gnu/ipc/ipdl/PProcessHangMonitorChild.cpp#108)
* [PARENT] '''HangMonitorParent::RecvHangEvidence''' is called when '''PProcessHangMonitorParent''' receives a message from the child process (https://dxr.mozilla.org/mozilla-central/source/obj-x86_64-unknown-linux-gnu/ipc/ipdl/PProcessHangMonitorParent.cpp#288)
* [PARENT] '''HangMonitorParent::RecvHangEvidence''' sends out a "process-hang-report" event by creating a '''HangObserverNotifier''' task (https://dxr.mozilla.org/mozilla-central/source/dom/ipc/ProcessHangMonitor.cpp#610)
* [PARENT] '''ProcessHangMonitor.reportHang''' is called when the '''ProcessHangMonitor''' receives a "process-hang-report" event (https://dxr.mozilla.org/mozilla-central/source/browser/modules/ProcessHangMonitor.jsm#66)
* [PARENT] JS function '''ProcessHangMonitor.reportHang''' accumulates the SLOW_SCRIPT_NOTICE_COUNT histogram (https://dxr.mozilla.org/mozilla-central/source/browser/modules/ProcessHangMonitor.jsm#403)
* I've checked that this is currently the only code path that results in SLOW_SCRIPT_NOTICE_COUNT being incremented.
 
Have we tested the metric to make sure it's working properly in e10s?
 
* There should be no differences in the slow script '''reporting''' mechanism between e10s and non-e10s; 1 call to ShowSlowScriptDialog means 1 addition to the histogram regardless of e10s setting. Manual testing supports this.
* The timeout has changed from 2 to 10 in e10s builds (see https://hg.mozilla.org/mozilla-central/rev/63680efe6d55#l35.12 for before and https://hg.mozilla.org/mozilla-central/rev/5002e9c06365#l2.13 for after). :azhang is currently investigating this.

Revision as of 21:17, 22 February 2016

e10s must not cause the slow-script dialog to appear more often

  • a/b testing on beta should indicate that the slow script dialog appears no more often than before

RASCI:

  • Responsible: azhang
  • Accountable: bsmedberg
  • Supporting:
  • Consulted:
  • Informed: cpeterson, elan

Technical details:

  • The slow script timeout will not change with e10s
  • SLOW_SCRIPT_NOTICE_COUNT is the telemetry histogram

Links:

Analysis results: SLOW_SCRIPT_NOTICE_COUNT shows up significantly more often in e10s. Analysis was reviewed by: rvitillo

How slow script notice count works on non-e10s:

How slow script notice count works on e10s:

Have we tested the metric to make sure it's working properly in e10s?

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