Issack John (Gerrit)

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Oct 9, 2025, 1:22:58 PMOct 9

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Yang Guo (Gerrit)

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Oct 10, 2025, 5:56:53 AMOct 10

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File-level comment, Patchset 2 (Latest):

Yang Guo . resolved

Please file

File include/v8-profiler.h

Line 54, Patchset 2 (Latest): kSelfProfiling = 2,

Yang Guo . unresolved

This is not used anywhere. I assume that this will be used from Blink? I further assume that there will be a change in DevTools frontend to make use of this information?

Can you file a crbug so that we can track the rationale of this change and the associated CLs?

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Yang Guo (Gerrit)

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Oct 10, 2025, 5:57:25 AMOct 10

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File-level comment, Patchset 2 (Latest):

Yang Guo . resolved

Jack, could you take a cursory look at this? Also, I anticipate a frontend change based on this.

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Issack John (Gerrit)

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Oct 10, 2025, 12:09:41 PMOct 10

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File include/v8-profiler.h

Line 54, Patchset 2 (Latest): kSelfProfiling = 2,

Yang Guo . unresolved

This is not used anywhere. I assume that this will be used from Blink? I further assume that there will be a change in DevTools frontend to make use of this information?
Can you file a crbug so that we can track the rationale of this change and the associated CLs?

Issack John

Yes, it will be used from blink. The CL description is long, so it got cut off but the associated CLs are at the bottom along with the crbug.

Related CLs:
DevTools CL: https://crrev.com/c/6877206
Chromium CL: https://crrev.com/c/6874588

Bug: 375614293

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Yang Guo (Gerrit)

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Oct 13, 2025, 2:56:55 AMOct 13

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File include/v8-profiler.h

Line 54, Patchset 2 (Latest): kSelfProfiling = 2,

Yang Guo . unresolved

This is not used anywhere. I assume that this will be used from Blink? I further assume that there will be a change in DevTools frontend to make use of this information?
Can you file a crbug so that we can track the rationale of this change and the associated CLs?

Issack John

Yes, it will be used from blink. The CL description is long, so it got cut off but the associated CLs are at the bottom along with the crbug.
Related CLs:
DevTools CL: https://crrev.com/c/6877206
Chromium CL: https://crrev.com/c/6874588
Bug: 375614293

Yang Guo

Indeed I overlooked the content below the fold. Thanks!

I'd still like Jack to take a look, especially in combination with the DevTools CL.

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Issack John (Gerrit)

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Oct 14, 2025, 2:17:08 PMOct 14

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File include/v8-profiler.h

Line 54, Patchset 2 (Latest): kSelfProfiling = 2,

Yang Guo . unresolved

This is not used anywhere. I assume that this will be used from Blink? I further assume that there will be a change in DevTools frontend to make use of this information?
Can you file a crbug so that we can track the rationale of this change and the associated CLs?

Issack John

Yes, it will be used from blink. The CL description is long, so it got cut off but the associated CLs are at the bottom along with the crbug.
Related CLs:
DevTools CL: https://crrev.com/c/6877206
Chromium CL: https://crrev.com/c/6874588
Bug: 375614293

Yang Guo

Indeed I overlooked the content below the fold. Thanks!
I'd still like Jack to take a look, especially in combination with the DevTools CL.

Issack John

SGTM

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Issack John (Gerrit)

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Oct 24, 2025, 12:03:21 PM (13 days ago) Oct 24

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File-level comment, Patchset 2 (Latest):

Yang Guo . resolved

Jack, could you take a cursory look at this? Also, I anticipate a frontend change based on this.

Issack John

Gentle ping. jacktfranklin@ 😊

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Jack Franklin (Gerrit)

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Nov 3, 2025, 4:01:51 AM (3 days ago) Nov 3

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File include/v8-profiler.h

Line 54, Patchset 2 (Latest): kSelfProfiling = 2,

Yang Guo . unresolved

This is not used anywhere. I assume that this will be used from Blink? I further assume that there will be a change in DevTools frontend to make use of this information?
Can you file a crbug so that we can track the rationale of this change and the associated CLs?

Issack John

Yes, it will be used from blink. The CL description is long, so it got cut off but the associated CLs are at the bottom along with the crbug.
Related CLs:
DevTools CL: https://crrev.com/c/6877206
Chromium CL: https://crrev.com/c/6874588
Bug: 375614293

Yang Guo

Indeed I overlooked the content below the fold. Thanks!
I'd still like Jack to take a look, especially in combination with the DevTools CL.

Issack John

SGTM

Jack Franklin

Apologies for the delay here - this LGTM (I cannot +1 as I don't have the required permissions on V8). I will leave a few notes on the frontend CL but broadly this looks like a great improvement so thank you!

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Yang Guo (Gerrit)

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Nov 3, 2025, 4:03:53 AM (3 days ago) Nov 3

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Yang Guo voted Code-Review+1

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Michael Lippautz (Gerrit)

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Nov 3, 2025, 4:14:11 AM (3 days ago) Nov 3

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Michael Lippautz voted and added 4 comments

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File-level comment, Patchset 2 (Latest):

Michael Lippautz . resolved

lgtm

File include/v8-profiler.h

Line 55, Patchset 2 (Latest): kInternal = 3,

Michael Lippautz . unresolved

nit: Can you add one-liners to the fields? `kUnspecified` vs `kInternal` could use a clarification.

Line 51, Patchset 2 (Latest):enum class CpuProfileSource : uint8_t {

Michael Lippautz . unresolved

nit: Please add a small comment explaining the enum.

File src/profiler/profile-generator.cc

Line 575, Patchset 2 (Latest):const char* CpuProfileSourceToTraceString(v8::CpuProfileSource source) {

Michael Lippautz . unresolved

nit: `ToString()` is fine as we use the same convention in e.g. `globals.h`, see https://source.chromium.org/chromium/chromium/src/+/main:v8/src/common/globals.h;l=1427?q=globals.h&ss=chromium

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Issack John (Gerrit)

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Nov 3, 2025, 4:18:29 PM (3 days ago) Nov 3

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Issack John voted and added 5 comments

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File-level comment, Patchset 2:

Issack John . resolved

Thank you for the reviews! 😊

File include/v8-profiler.h

Line 55, Patchset 2: kInternal = 3,

Michael Lippautz . resolved

nit: Can you add one-liners to the fields? `kUnspecified` vs `kInternal` could use a clarification.

Issack John

Done

Line 54, Patchset 2: kSelfProfiling = 2,

Yang Guo . resolved

This is not used anywhere. I assume that this will be used from Blink? I further assume that there will be a change in DevTools frontend to make use of this information?
Can you file a crbug so that we can track the rationale of this change and the associated CLs?

Issack John

Yes, it will be used from blink. The CL description is long, so it got cut off but the associated CLs are at the bottom along with the crbug.
Related CLs:
DevTools CL: https://crrev.com/c/6877206
Chromium CL: https://crrev.com/c/6874588
Bug: 375614293

Yang Guo

Indeed I overlooked the content below the fold. Thanks!
I'd still like Jack to take a look, especially in combination with the DevTools CL.

Issack John

SGTM

Jack Franklin

Apologies for the delay here - this LGTM (I cannot +1 as I don't have the required permissions on V8). I will leave a few notes on the frontend CL but broadly this looks like a great improvement so thank you!

Issack John

Thank you for the review! 😊

Line 51, Patchset 2:enum class CpuProfileSource : uint8_t {

Michael Lippautz . resolved

nit: Please add a small comment explaining the enum.

Issack John

Done

File src/profiler/profile-generator.cc

Line 575, Patchset 2:const char* CpuProfileSourceToTraceString(v8::CpuProfileSource source) {

Michael Lippautz . resolved

nit: `ToString()` is fine as we use the same convention in e.g. `globals.h`, see https://source.chromium.org/chromium/chromium/src/+/main:v8/src/common/globals.h;l=1427?q=globals.h&ss=chromium

Issack John

Done

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Michael Lippautz (Gerrit)

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Nov 4, 2025, 8:01:28 AM (2 days ago) Nov 4

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Michael Lippautz voted Code-Review+1

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Issack John (Gerrit)

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Nov 4, 2025, 12:09:53 PM (2 days ago) Nov 4

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File-level comment, Patchset 4 (Latest):

Issack John . resolved

PTAL yangguo@, your vote got reset.

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Yang Guo (Gerrit)

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Nov 4, 2025, 12:33:54 PM (2 days ago) Nov 4

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Issack John (Gerrit)

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Nov 4, 2025, 12:34:50 PM (2 days ago) Nov 4

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Issack John voted Commit-Queue+2

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V8 LUCI CQ (Gerrit)

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Nov 4, 2025, 12:42:27 PM (2 days ago) Nov 4

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V8 LUCI CQ submitted the change

Change information

Commit message:

[profiler] Add CpuProfileSource to distinguish concurrent profile streams

DevTools merges concurrent CPU profile streams on the same thread, which
corrupts JavaScript attribution when multiple profiling sources are active
simultaneously. For example, when JS Self-Profiling API runs concurrently
with internal V8 tracing, their samples get incorrectly merged into a
single profile.

This CL adds a CpuProfileSource enum to tag profile events at their source,
enabling DevTools to keep streams separate and maintain correct attribution.

JS Self-Profiling will pass kSelfProfiling in follow-up Chromium CL



Related CLs:
DevTools CL: https://crrev.com/c/6877206
Chromium CL: https://crrev.com/c/6874588

Bug: 375614293

Change-Id: I8fda56acedaaeadbbe4f911b27d36658d8248393

Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/7004962

Reviewed-by: Michael Lippautz <mlip...@chromium.org>

Reviewed-by: Yang Guo <yan...@chromium.org>

Commit-Queue: Issack John <issac...@microsoft.com>

Cr-Commit-Position: refs/heads/main@{#103512}

Files:

M include/v8-profiler.h
M src/api/api.cc
M src/inspector/v8-profiler-agent-impl.cc
M src/profiler/profile-generator.cc
M src/profiler/tracing-cpu-profiler.cc
M test/cctest/test-cpu-profiler.cc

Change size: M

Delta: 6 files changed, 88 insertions(+), 5 deletions(-)

Branch: refs/heads/main

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Code-Review: +1 by Yang Guo, +1 by Michael Lippautz

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Rezvan Mahdavi Hezaveh (Gerrit)

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Nov 4, 2025, 6:24:04 PM (2 days ago) Nov 4

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Rezvan Mahdavi Hezaveh has created a revert of this change

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[profiler] Add CpuProfileSource to distinguish concurrent profile streams [v8/v8 : main]

Issack John (Gerrit)

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Yang Guo (Gerrit)

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V8 LUCI CQ (Gerrit)

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