1513737 - Stop using Array.shift when mapping pause points

Status: RESOLVED FIXED

(DevTools :: Debugger, defect, P1)

Description

[Jason Laster [:jlast]]

We found that Array.shift had a significant slow down when mapping pause points

https://treeherder.mozilla.org/perf.html#/comparesubtest?originalProject=mozilla-central&newProject=try&newRevision=b312ec87a42574e3c252acd65d2d46735d85e649&originalSignature=f79b6a4f1f8f53326d3056f6c8008c0ff4de0a94&newSignature=f79b6a4f1f8f53326d3056f6c8008c0ff4de0a94&framework=12&selectedTimeRange=172800

Comment 1

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/622a47b9c5a8
Stop using Array.shift when mapping pause points. r=dwalsh

Comment 2

[Natalia Csoregi [:nataliaCs]]

Backed out for devtools failures on devtools/client/debugger/new/test/mochitest/browser_dbg-debugger-buttons.js

backout: https://hg.mozilla.org/integration/mozilla-inbound/rev/a32c6af527d082f48a11c0b51d69cddb65cb5fc2

push with failures: https://treeherder.mozilla.org/#/jobs?repo=mozilla-inbound&revision=622a47b9c5a897f92aec7b4a5dcf8ad93d4443f5&searchStr=devtools&group_state=expanded&selectedJob=216868585

failure log: https://treeherder.mozilla.org/logviewer.html#/jobs?job_id=216868585&repo=mozilla-inbound&lineNumber=2402

12:15:45     INFO - Console message: [JavaScript Warning: "Removed unsafe attribute. Element: svg. Attribute: xlink." {file: "resource://devtools/client/shared/vendor/react-dom.js" line: 5811}]
12:15:45     INFO - Console message: [JavaScript Warning: "Removed unsafe attribute. Element: svg. Attribute: xlink." {file: "resource://devtools/client/shared/vendor/react-dom.js" line: 5811}]
12:15:45     INFO - Console message: [JavaScript Warning: "Removed unsafe attribute. Element: svg. Attribute: xlink." {file: "resource://devtools/client/shared/vendor/react-dom.js" line: 5811}]
12:15:45     INFO - Console message: [JavaScript Warning: "Removed unsafe attribute. Element: svg. Attribute: xmlns." {file: "resource://devtools/client/shared/vendor/react-dom.js" line: 5811}]
12:15:45     INFO - Console message: [JavaScript Warning: "Removed unsafe attribute. Element: svg. Attribute: xlink." {file: "resource://devtools/client/shared/vendor/react-dom.js" line: 5811}]
12:15:45     INFO - Console message: [JavaScript Warning: "Removed unsafe attribute. Element: svg. Attribute: xlink." {file: "resource://devtools/client/shared/vendor/react-dom.js" line: 5811}]
12:15:45     INFO - Console message: [JavaScript Warning: "Removed unsafe attribute. Element: svg. Attribute: xlink." {file: "resource://devtools/client/shared/vendor/react-dom.js" line: 5811}]
12:15:45     INFO - Console message: [JavaScript Warning: "Removed unsafe attribute. Element: svg. Attribute: xmlns." {file: "resource://devtools/client/shared/vendor/react-dom.js" line: 5811}]
12:15:45     INFO - Console message: [JavaScript Warning: "Removed unsafe attribute. Element: svg. Attribute: xmlns." {file: "resource://devtools/client/shared/vendor/react-dom.js" line: 5811}]
12:15:45     INFO - Finished waiting for state change: paused
12:15:45     INFO - Finished waiting for state change: paused
12:15:45     INFO - Waiting for state change: selected source
12:15:45     INFO - Finished waiting for state change: selected source
12:15:45     INFO - TEST-PASS | devtools/client/debugger/new/test/mochitest/browser_dbg-debugger-buttons.js | top frame's source is selected - 
12:15:45     INFO - TEST-PASS | devtools/client/debugger/new/test/mochitest/browser_dbg-debugger-buttons.js | Line is highlighted as paused - 
12:15:45     INFO - TEST-PASS | devtools/client/debugger/new/test/mochitest/browser_dbg-debugger-buttons.js | There is only one line - 
12:15:45     INFO - TEST-PASS | devtools/client/debugger/new/test/mochitest/browser_dbg-debugger-buttons.js | debug line is visible - 
12:15:45     INFO - TEST-PASS | devtools/client/debugger/new/test/mochitest/browser_dbg-debugger-buttons.js | expression is highlighted as paused - 
12:15:45     INFO - TEST-PASS | devtools/client/debugger/new/test/mochitest/browser_dbg-debugger-buttons.js | gutter is visible - 
12:15:45     INFO - Waiting for COMMAND to dispatch 1 time(s)
12:15:45     INFO - Console message: [JavaScript Warning: "Removed unsafe attribute. Element: svg. Attribute: xmlns." {file: "resource://devtools/client/shared/vendor/react-dom.js" line: 5811}]
12:15:45     INFO - Console message: [JavaScript Error: "The character encoding of the HTML document was not declared. The document will render with garbled text in some browser configurations if the document contains characters from outside the US-ASCII range. The character encoding of the page must be declared in the document or in the transfer protocol." {file: "http://example.com/browser/devtools/client/debugger/new/test/mochitest/examples/doc-debugger-statements.html" line: 0}]
12:15:45     INFO - COMMAND dispatched 1 time(s)
12:15:45     INFO - Waiting for state change: paused
12:15:45     INFO - Buffered messages finished
12:15:45     INFO - TEST-UNEXPECTED-FAIL | devtools/client/debugger/new/test/mochitest/browser_dbg-debugger-buttons.js | Test timed out - 
12:15:45     INFO - Removing tab.
12:15:45     INFO - Waiting for event: 'TabClose' on [object XULElement].
12:15:45     INFO - Got event: 'TabClose' on [object XULElement].
12:15:45     INFO - Tab removed and finished closing
12:15:45     INFO - GECKO(870) | MEMORY STAT | vsize 4642MB | residentFast 573MB | heapAllocated 142MB
12:15:45     INFO - TEST-OK | devtools/client/debugger/new/test/mochitest/browser_dbg-debugger-buttons.js | took 45320ms

Comment 3

[Jason Laster [:jlast]]

sorry, i missed a try failure. This is a revised run that should be green.

https://treeherder.mozilla.org/#/jobs?repo=try&revision=50d38ab1a43fe9f6a6a78b34aeefce08fde6bda6

Comment 4

[Jason Laster [:jlast]]

w/ a feature flag
https://treeherder.mozilla.org/#/jobs?repo=try&revision=04b72df93051f4701a9fd6d0daa26ae222231c1f

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/b71a3c86f994
Stop using Array.shift when mapping pause points. r=dwalsh

Comment 8

[Razvan Maries]

https://hg.mozilla.org/mozilla-central/rev/b71a3c86f994

Comment 9

[Jason Laster [:jlast]]

Attachment: beta-shift.patch

[Beta/Release Uplift Approval Request]

Feature/Bug causing the regression: Bug 1511352

User impact if declined: the debugger is 800% slower

Is this code covered by automated tests?: Yes

Has the fix been verified in Nightly?: Yes

Needs manual test from QE?: No

If yes, steps to reproduce: 

List of other uplifts needed: None

Risk to taking this patch: Low

Why is the change risky/not risky? (and alternatives if risky): because it only touches the debugger and  turns off an unused feature.

String changes made/needed:

Comment 10

[Ritu Kothari (:ritu) (Inactive, please n-i to RyanVM, jcristau, or pascal)]

Comment on attachment 9032055 [details] [diff] [review]
beta-shift.patch

With that kind of perf win, we should definitely take it in Beta65+.

Comment 11

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/releases/mozilla-beta/rev/f0978d33730c