src: enable detailed source positions in V8#24274
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Original commit message: [profiler] introduce API to enable detailed source positions This allows Node.js to enable detailed source positions for optimized code early on, without having to pass a flag string. [email protected] Change-Id: Ie74ea41f600cf6e31acbe802116df4976ccf1c75 Reviewed-on: https://chromium-review.googlesource.com/c/1319757 Commit-Queue: Yang Guo <[email protected]> Reviewed-by: Peter Marshall <[email protected]> Cr-Commit-Position: refs/heads/master@{nodejs#57380}
nodejs-github-bot added the lib / src 
devsnek approved these changes Nov 9, 2018
jasnell approved these changes Nov 9, 2018
psmarshall approved these changes Nov 9, 2018
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psmarshall commented Nov 9, 2018
psmarshall added v8 engine 
ofrobots approved these changes Nov 9, 2018
refack reviewed Nov 9, 2018
| isolate->SetMicrotasksPolicy(MicrotasksPolicy::kExplicit); | ||
| isolate->SetFatalErrorHandler(OnFatalError); | ||
| isolate->SetAllowWasmCodeGenerationCallback(AllowWasmCodeGenerationCallback); | ||
| v8::CpuProfiler::UseDetailedSourcePositionsForProfiling(isolate); |
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Question: does this have a penalty? And even if not could this be conditional on inspector being attached or profiler run requested (I mean is it possible)?
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The problem with only enabling this once the profiler run is requested is that functions that get optimized before profiling starts don't have the detailed line information. In the browser you can work around this by reloading the page with profiling enabled (devtools has a button for this) but for a running Node instance this is not really feasible, particularly if you want to debug some rarely-occurring thing. Unfortunately we see this in the wild quite a bit so having it on by default makes sense IMO.
The overhead is very low - on average it makes no difference, it the worst case a few percent increase in optimized compile time, but this is currently being moved off-thread anyway (plus the general performance boost of upgrading the V8 version is going to easily outweigh this).
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In the browser you can work around this by reloading the page with profiling enabled
I'm thinking about this some more...
For node we have one main way to enable inspetor, via CLI args. There are two other ways which I don't have usage information about SIGUSR and inspector.open().
It might be a better balance to turn this on only for processes started with inspector listening, and save the performance cost for regular runs. IIUC the down side is less accurate code position information?
I'm ambivalent...
/CC @nodejs/performance
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CpuProfiler can be also used without inspector, see e.g. NPM modules like v8-profiler. There are tools out in the wild which start profiling automatically for some time if they notice performance issues.
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It's also possible to use the CPU profiler directly through the V8 API without the inspector and there are some native modules that do this - that approach wouldn't work for them as far as I understand
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The thoughts leading to this were:
- It's hard to foresee whether the user is going to profile, both for Chrome and Node.
- For Chrome, you can at least reload, with DevTools open.
- Node.js does not have the reload option.
- Adding more accurate data has a small one-time cost for the script. Chrome suffers a bit more for this as you pay more for optimizing compiles, possibly while starting up a page, and this occurs on every page navigation. Node.js does not encounter new scripts to compile and optimize as often.
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I agree that it's a tough call:
slightly slower compile time but for everyone ⚖️ improvement not available but only for profiling started out-of-band
mmarchini approved these changes Nov 9, 2018
cjihrig approved these changes Nov 9, 2018
refack approved these changes Nov 12, 2018
BridgeAR approved these changes Nov 12, 2018
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hashseed commented Nov 13, 2018
Seems like we got a few timeouts on SmartOS. How should we proceed with this PR? |
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refack commented Nov 13, 2018
They might be flakes https://ci.nodejs.org/job/node-test-pull-request/18574/ |
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hashseed commented Nov 14, 2018
Looks like some other tests failed this time. |
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Trott commented Nov 14, 2018
Trott pushed a commit to Trott/io.js that referenced this pull request Nov 14, 2018
Original commit message: [profiler] introduce API to enable detailed source positions This allows Node.js to enable detailed source positions for optimized code early on, without having to pass a flag string. [email protected] Change-Id: Ie74ea41f600cf6e31acbe802116df4976ccf1c75 Reviewed-on: https://chromium-review.googlesource.com/c/1319757 Commit-Queue: Yang Guo <[email protected]> Reviewed-by: Peter Marshall <[email protected]> Cr-Commit-Position: refs/heads/master@{nodejs#57380} PR-URL: nodejs#24274 Reviewed-By: Gus Caplan <[email protected]> Reviewed-By: James M Snell <[email protected]> Reviewed-By: Peter Marshall <[email protected]> Reviewed-By: Ali Ijaz Sheikh <[email protected]> Reviewed-By: Matheus Marchini <[email protected]> Reviewed-By: Colin Ihrig <[email protected]> Reviewed-By: Refael Ackermann <[email protected]> Reviewed-By: Ruben Bridgewater <[email protected]>
Trott pushed a commit to Trott/io.js that referenced this pull request Nov 14, 2018
PR-URL: nodejs#24274 Reviewed-By: Gus Caplan <[email protected]> Reviewed-By: James M Snell <[email protected]> Reviewed-By: Peter Marshall <[email protected]> Reviewed-By: Ali Ijaz Sheikh <[email protected]> Reviewed-By: Matheus Marchini <[email protected]> Reviewed-By: Colin Ihrig <[email protected]> Reviewed-By: Refael Ackermann <[email protected]> Reviewed-By: Ruben Bridgewater <[email protected]>
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Trott commented Nov 14, 2018
Landed in c1d18a0...e2a8e32 |
BridgeAR pushed a commit that referenced this pull request Nov 14, 2018
Original commit message: [profiler] introduce API to enable detailed source positions This allows Node.js to enable detailed source positions for optimized code early on, without having to pass a flag string. [email protected] Change-Id: Ie74ea41f600cf6e31acbe802116df4976ccf1c75 Reviewed-on: https://chromium-review.googlesource.com/c/1319757 Commit-Queue: Yang Guo <[email protected]> Reviewed-by: Peter Marshall <[email protected]> Cr-Commit-Position: refs/heads/master@{#57380} PR-URL: #24274 Reviewed-By: Gus Caplan <[email protected]> Reviewed-By: James M Snell <[email protected]> Reviewed-By: Peter Marshall <[email protected]> Reviewed-By: Ali Ijaz Sheikh <[email protected]> Reviewed-By: Matheus Marchini <[email protected]> Reviewed-By: Colin Ihrig <[email protected]> Reviewed-By: Refael Ackermann <[email protected]> Reviewed-By: Ruben Bridgewater <[email protected]>
BridgeAR pushed a commit that referenced this pull request Nov 14, 2018
PR-URL: #24274 Reviewed-By: Gus Caplan <[email protected]> Reviewed-By: James M Snell <[email protected]> Reviewed-By: Peter Marshall <[email protected]> Reviewed-By: Ali Ijaz Sheikh <[email protected]> Reviewed-By: Matheus Marchini <[email protected]> Reviewed-By: Colin Ihrig <[email protected]> Reviewed-By: Refael Ackermann <[email protected]> Reviewed-By: Ruben Bridgewater <[email protected]>
kiyomizumia pushed a commit to kiyomizumia/node that referenced this pull request Nov 15, 2018
Original commit message: [profiler] introduce API to enable detailed source positions This allows Node.js to enable detailed source positions for optimized code early on, without having to pass a flag string. [email protected] Change-Id: Ie74ea41f600cf6e31acbe802116df4976ccf1c75 Reviewed-on: https://chromium-review.googlesource.com/c/1319757 Commit-Queue: Yang Guo <[email protected]> Reviewed-by: Peter Marshall <[email protected]> Cr-Commit-Position: refs/heads/master@{nodejs#57380} PR-URL: nodejs#24274 Reviewed-By: Gus Caplan <[email protected]> Reviewed-By: James M Snell <[email protected]> Reviewed-By: Peter Marshall <[email protected]> Reviewed-By: Ali Ijaz Sheikh <[email protected]> Reviewed-By: Matheus Marchini <[email protected]> Reviewed-By: Colin Ihrig <[email protected]> Reviewed-By: Refael Ackermann <[email protected]> Reviewed-By: Ruben Bridgewater <[email protected]>
kiyomizumia pushed a commit to kiyomizumia/node that referenced this pull request Nov 15, 2018
PR-URL: nodejs#24274 Reviewed-By: Gus Caplan <[email protected]> Reviewed-By: James M Snell <[email protected]> Reviewed-By: Peter Marshall <[email protected]> Reviewed-By: Ali Ijaz Sheikh <[email protected]> Reviewed-By: Matheus Marchini <[email protected]> Reviewed-By: Colin Ihrig <[email protected]> Reviewed-By: Refael Ackermann <[email protected]> Reviewed-By: Ruben Bridgewater <[email protected]>
BridgeAR pushed a commit that referenced this pull request Nov 15, 2018
Original commit message: [profiler] introduce API to enable detailed source positions This allows Node.js to enable detailed source positions for optimized code early on, without having to pass a flag string. [email protected] Change-Id: Ie74ea41f600cf6e31acbe802116df4976ccf1c75 Reviewed-on: https://chromium-review.googlesource.com/c/1319757 Commit-Queue: Yang Guo <[email protected]> Reviewed-by: Peter Marshall <[email protected]> Cr-Commit-Position: refs/heads/master@{#57380} PR-URL: #24274 Reviewed-By: Gus Caplan <[email protected]> Reviewed-By: James M Snell <[email protected]> Reviewed-By: Peter Marshall <[email protected]> Reviewed-By: Ali Ijaz Sheikh <[email protected]> Reviewed-By: Matheus Marchini <[email protected]> Reviewed-By: Colin Ihrig <[email protected]> Reviewed-By: Refael Ackermann <[email protected]> Reviewed-By: Ruben Bridgewater <[email protected]>
BridgeAR pushed a commit that referenced this pull request Nov 15, 2018
PR-URL: #24274 Reviewed-By: Gus Caplan <[email protected]> Reviewed-By: James M Snell <[email protected]> Reviewed-By: Peter Marshall <[email protected]> Reviewed-By: Ali Ijaz Sheikh <[email protected]> Reviewed-By: Matheus Marchini <[email protected]> Reviewed-By: Colin Ihrig <[email protected]> Reviewed-By: Refael Ackermann <[email protected]> Reviewed-By: Ruben Bridgewater <[email protected]>
This was referenced Nov 15, 2018
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targos commented Nov 17, 2018
The commits from this PR were reverted in #24394 (V8 tests were broken). Please open a new pull request to get them back in. N.B.: I didn't add the |
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addaleax pushed a commit that referenced this pull request Nov 23, 2018
Original commit message: [profiler] introduce API to enable detailed source positions This allows Node.js to enable detailed source positions for optimized code early on, without having to pass a flag string. [email protected] Change-Id: Ie74ea41f600cf6e31acbe802116df4976ccf1c75 Reviewed-on: https://chromium-review.googlesource.com/c/1319757 Commit-Queue: Yang Guo <[email protected]> Reviewed-by: Peter Marshall <[email protected]> Cr-Commit-Position: refs/heads/master@{#57380} Refs: v8/v8@073073b PR-URL: #24515 Refs: #24274 Refs: #24394 Refs: #24393 Reviewed-By: Michaël Zasso <[email protected]> Reviewed-By: Joyee Cheung <[email protected]> Reviewed-By: Peter Marshall <[email protected]> Reviewed-By: James M Snell <[email protected]> Reviewed-By: Refael Ackermann <[email protected]>
addaleax pushed a commit that referenced this pull request Nov 23, 2018
PR-URL: #24515 Refs: #24274 Refs: #24394 Refs: #24393 Reviewed-By: Michaël Zasso <[email protected]> Reviewed-By: Joyee Cheung <[email protected]> Reviewed-By: Peter Marshall <[email protected]> Reviewed-By: James M Snell <[email protected]> Reviewed-By: Refael Ackermann <[email protected]>
targos pushed a commit that referenced this pull request Nov 24, 2018
Original commit message: [profiler] introduce API to enable detailed source positions This allows Node.js to enable detailed source positions for optimized code early on, without having to pass a flag string. [email protected] Change-Id: Ie74ea41f600cf6e31acbe802116df4976ccf1c75 Reviewed-on: https://chromium-review.googlesource.com/c/1319757 Commit-Queue: Yang Guo <[email protected]> Reviewed-by: Peter Marshall <[email protected]> Cr-Commit-Position: refs/heads/master@{#57380} Refs: v8/v8@073073b PR-URL: #24515 Refs: #24274 Refs: #24394 Refs: #24393 Reviewed-By: Michaël Zasso <[email protected]> Reviewed-By: Joyee Cheung <[email protected]> Reviewed-By: Peter Marshall <[email protected]> Reviewed-By: James M Snell <[email protected]> Reviewed-By: Refael Ackermann <[email protected]>
targos pushed a commit that referenced this pull request Nov 24, 2018
PR-URL: #24515 Refs: #24274 Refs: #24394 Refs: #24393 Reviewed-By: Michaël Zasso <[email protected]> Reviewed-By: Joyee Cheung <[email protected]> Reviewed-By: Peter Marshall <[email protected]> Reviewed-By: James M Snell <[email protected]> Reviewed-By: Refael Ackermann <[email protected]>
rvagg pushed a commit that referenced this pull request Nov 28, 2018
Original commit message: [profiler] introduce API to enable detailed source positions This allows Node.js to enable detailed source positions for optimized code early on, without having to pass a flag string. [email protected] Change-Id: Ie74ea41f600cf6e31acbe802116df4976ccf1c75 Reviewed-on: https://chromium-review.googlesource.com/c/1319757 Commit-Queue: Yang Guo <[email protected]> Reviewed-by: Peter Marshall <[email protected]> Cr-Commit-Position: refs/heads/master@{#57380} Refs: v8/v8@073073b PR-URL: #24515 Refs: #24274 Refs: #24394 Refs: #24393 Reviewed-By: Michaël Zasso <[email protected]> Reviewed-By: Joyee Cheung <[email protected]> Reviewed-By: Peter Marshall <[email protected]> Reviewed-By: James M Snell <[email protected]> Reviewed-By: Refael Ackermann <[email protected]>
rvagg pushed a commit that referenced this pull request Nov 28, 2018
PR-URL: #24515 Refs: #24274 Refs: #24394 Refs: #24393 Reviewed-By: Michaël Zasso <[email protected]> Reviewed-By: Joyee Cheung <[email protected]> Reviewed-By: Peter Marshall <[email protected]> Reviewed-By: James M Snell <[email protected]> Reviewed-By: Refael Ackermann <[email protected]>
targos pushed a commit to targos/node that referenced this pull request Dec 4, 2018
Original commit message: [profiler] introduce API to enable detailed source positions This allows Node.js to enable detailed source positions for optimized code early on, without having to pass a flag string. [email protected] Change-Id: Ie74ea41f600cf6e31acbe802116df4976ccf1c75 Reviewed-on: https://chromium-review.googlesource.com/c/1319757 Commit-Queue: Yang Guo <[email protected]> Reviewed-by: Peter Marshall <[email protected]> Cr-Commit-Position: refs/heads/master@{nodejs#57380} Refs: v8/v8@073073b PR-URL: nodejs#24515 Refs: nodejs#24274 Refs: nodejs#24394 Refs: nodejs#24393 Reviewed-By: Michaël Zasso <[email protected]> Reviewed-By: Joyee Cheung <[email protected]> Reviewed-By: Peter Marshall <[email protected]> Reviewed-By: James M Snell <[email protected]> Reviewed-By: Refael Ackermann <[email protected]>
pullbot pushed a commit to shakir-abdo/node that referenced this pull request Dec 6, 2018
Original commit message: [profiler] introduce API to enable detailed source positions This allows Node.js to enable detailed source positions for optimized code early on, without having to pass a flag string. [email protected] Change-Id: Ie74ea41f600cf6e31acbe802116df4976ccf1c75 Reviewed-on: https://chromium-review.googlesource.com/c/1319757 Commit-Queue: Yang Guo <[email protected]> Reviewed-by: Peter Marshall <[email protected]> Cr-Commit-Position: refs/heads/master@{nodejs#57380} Refs: v8/v8@073073b PR-URL: nodejs#24515 Refs: nodejs#24274 Refs: nodejs#24394 Refs: nodejs#24393 Reviewed-By: Michaël Zasso <[email protected]> Reviewed-By: Joyee Cheung <[email protected]> Reviewed-By: Peter Marshall <[email protected]> Reviewed-By: James M Snell <[email protected]> Reviewed-By: Refael Ackermann <[email protected]>
refack pushed a commit to refack/node that referenced this pull request Jan 14, 2019
Original commit message: [profiler] introduce API to enable detailed source positions This allows Node.js to enable detailed source positions for optimized code early on, without having to pass a flag string. [email protected] Change-Id: Ie74ea41f600cf6e31acbe802116df4976ccf1c75 Reviewed-on: https://chromium-review.googlesource.com/c/1319757 Commit-Queue: Yang Guo <[email protected]> Reviewed-by: Peter Marshall <[email protected]> Cr-Commit-Position: refs/heads/master@{nodejs#57380} Refs: v8/v8@073073b PR-URL: nodejs#24515 Refs: nodejs#24274 Refs: nodejs#24394 Refs: nodejs#24393 Reviewed-By: Michaël Zasso <[email protected]> Reviewed-By: Joyee Cheung <[email protected]> Reviewed-By: Peter Marshall <[email protected]> Reviewed-By: James M Snell <[email protected]> Reviewed-By: Refael Ackermann <[email protected]>
refack pushed a commit to refack/node that referenced this pull request Jan 14, 2019
PR-URL: nodejs#24515 Refs: nodejs#24274 Refs: nodejs#24394 Refs: nodejs#24393 Reviewed-By: Michaël Zasso <[email protected]> Reviewed-By: Joyee Cheung <[email protected]> Reviewed-By: Peter Marshall <[email protected]> Reviewed-By: James M Snell <[email protected]> Reviewed-By: Refael Ackermann <[email protected]>
refack pushed a commit to refack/node that referenced this pull request Jan 14, 2019
Original commit message: [profiler] introduce API to enable detailed source positions This allows Node.js to enable detailed source positions for optimized code early on, without having to pass a flag string. [email protected] Change-Id: Ie74ea41f600cf6e31acbe802116df4976ccf1c75 Reviewed-on: https://chromium-review.googlesource.com/c/1319757 Commit-Queue: Yang Guo <[email protected]> Reviewed-by: Peter Marshall <[email protected]> Cr-Commit-Position: refs/heads/master@{nodejs#57380} Refs: v8/v8@073073b PR-URL: nodejs#24515 Refs: nodejs#24274 Refs: nodejs#24394 Refs: nodejs#24393 Reviewed-By: Michaël Zasso <[email protected]> Reviewed-By: Joyee Cheung <[email protected]> Reviewed-By: Peter Marshall <[email protected]> Reviewed-By: James M Snell <[email protected]> Reviewed-By: Refael Ackermann <[email protected]>
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Enable detailed source positions in generated code. When profiling, this gives a better mapping between profile samples to source text.
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make -j4 test(UNIX), orvcbuild test(Windows) passes