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src: fix race condition in ~NodeTraceBuffer #25896

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src: fix race condition in ~NodeTraceBuffer #25896

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@addaleax addaleax commented Feb 2, 2019 •
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Stress test CI looks good so far: https://ci.nodejs.org/job/node-stress-single-test/2146/ (✔️)

Libuv does not guarantee that handles have their close
callbacks called in the order in which they were added
(and in fact, currently calls them in reverse order).

This patch ensures that the flush_signal_ handle
is no longer in use (i.e. its close callback has already
been run) when we signal to the main thread that
~NodeTraceBuffer may be destroyed.

Credit for debugging goes to Gireesh Punathil.

Fixes: #25512

Checklist
  • make -j4 test (UNIX), or vcbuild test (Windows) passes
  • commit message follows commit guidelines

@addaleax
src: fix race condition in ~NodeTraceBuffer
60311fe 
Libuv does not guarantee that handles have their close
callbacks called in the order in which they were added
(and in fact, currently calls them in reverse order).

This patch ensures that the `flush_signal_` handle
is no longer in use (i.e. its close callback has already
been run) when we signal to the main thread that
`~NodeTraceBuffer` may be destroyed.

Credit for debugging goes to Gireesh Punathil.

Fixes: nodejs#25512
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@addaleax build started: https://ci.nodejs.org/blue/organizations/jenkins/node-test-pull-request-lite-pipeline/detail/node-test-pull-request-lite-pipeline/2493/pipeline

@nodejs-github-bot nodejs-github-bot added the c++ Issues and PRs that require attention from people who are familiar with C++. label Feb 2, 2019
@addaleax addaleax added trace_events Issues and PRs related to V8, Node.js core, and userspace code trace events. flaky-test Issues and PRs related to the tests with unstable failures on the CI. labels Feb 2, 2019
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addaleax commented Feb 2, 2019 •
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CI: https://ci.nodejs.org/job/node-test-pull-request/20544/ (✔️)

@addaleax addaleax mentioned this pull request Feb 2, 2019
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addaleax commented Feb 2, 2019

(btw, @gireeshpunathil, if you want I can add a Co-authored-by: for you -- you really did most of the work here!)

@refack refack mentioned this pull request Feb 2, 2019
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@addaleax addaleax added the author ready PRs that have at least one approval, no pending requests for changes, and a CI started. label Feb 2, 2019
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gireeshpunathil commented Feb 3, 2019 •
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I see the author-ready label; request some more time before anyone lands this as I am running the test and digesting the changes (it is not that my review is critical, but I have a lot of context on the issue).

@addaleax - sure, that makes sense to me, but if it can wait until I get back on this? Thanks for the kids kind words! For me, problem isolation and determination for bringing CI to stable itself is a great motivation. Walking backwards from the crash site upto the design is painful and error-prone, and the work is complete only if complemented and supported by experts like you who interpret the bits and pieces to make the translation pretty quick and promptly!

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Unfortunately the test still segfaults, but manifests in a slightly different manner. Determination needs to be made to see whether it is a fix not complete, or a side effect of the fix, or totally unrelated issue. Analysis in #25512

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Does the change in NodeTraceBuffer::ExitSignalCb applies to NodeTraceWriter::ExitSignalCb too?

@Trott Trott removed the author ready PRs that have at least one approval, no pending requests for changes, and a CI started. label Feb 3, 2019
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Trott commented Feb 3, 2019

(I removed author ready because @gireeshpunathil wants a bit more time to test and interpret.)

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@addaleax - I can confirm that the change is relevant to NodeTraceWriter::ExitSignalCb as well.

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@addaleax - I pushed a change to that effect, pls have a look.

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addaleax commented Feb 3, 2019

@gireeshpunathil Yes, your update LGTM 👍

CI: https://ci.nodejs.org/job/node-test-pull-request/20551/

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addaleax commented Feb 3, 2019

CI is good – @gireeshpunathil I assume you’re okay with landing this after the usual 48 hours?

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@addaleax - yes, LGTM.
(don't know of a process clause around approving a co-authored PR - a queer situation!)

@addaleax addaleax mentioned this pull request Feb 4, 2019
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addaleax commented Feb 4, 2019

Landed in 5506dcd 🎉

@addaleax addaleax closed this Feb 4, 2019
@addaleax addaleax deleted the trace-buffer-close branch February 4, 2019 17:19
addaleax added a commit that referenced this pull request Feb 4, 2019
@addaleax
src: fix race condition in ~NodeTraceBuffer
5506dcd 
Libuv does not guarantee that handles have their close
callbacks called in the order in which they were added
(and in fact, currently calls them in reverse order).

This patch ensures that the `flush_signal_` handle
is no longer in use (i.e. its close callback has already
been run) when we signal to the main thread that
`~NodeTraceBuffer` may be destroyed.

The same applies for `~NodeTraceWriter`.

Credit for debugging goes to Gireesh Punathil.

Fixes: #25512
Co-authored-by: Gireesh Punathil <[email protected]>

PR-URL: #25896
Reviewed-By: Colin Ihrig <[email protected]>
Reviewed-By: Refael Ackermann <[email protected]>
Reviewed-By: Gireesh Punathil <[email protected]>
Reviewed-By: Eugene Ostroukhov <[email protected]>
addaleax added a commit that referenced this pull request Feb 6, 2019
@addaleax
src: fix race condition in ~NodeTraceBuffer
e28d891 
Libuv does not guarantee that handles have their close
callbacks called in the order in which they were added
(and in fact, currently calls them in reverse order).

This patch ensures that the `flush_signal_` handle
is no longer in use (i.e. its close callback has already
been run) when we signal to the main thread that
`~NodeTraceBuffer` may be destroyed.

The same applies for `~NodeTraceWriter`.

Credit for debugging goes to Gireesh Punathil.

Fixes: #25512
Co-authored-by: Gireesh Punathil <[email protected]>

PR-URL: #25896
Reviewed-By: Colin Ihrig <[email protected]>
Reviewed-By: Refael Ackermann <[email protected]>
Reviewed-By: Gireesh Punathil <[email protected]>
Reviewed-By: Eugene Ostroukhov <[email protected]>
@targos targos mentioned this pull request Feb 14, 2019
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MylesBorins pushed a commit that referenced this pull request May 16, 2019
@addaleax @MylesBorins
src: fix race condition in ~NodeTraceBuffer
eb59d4e 
Libuv does not guarantee that handles have their close
callbacks called in the order in which they were added
(and in fact, currently calls them in reverse order).

This patch ensures that the `flush_signal_` handle
is no longer in use (i.e. its close callback has already
been run) when we signal to the main thread that
`~NodeTraceBuffer` may be destroyed.

The same applies for `~NodeTraceWriter`.

Credit for debugging goes to Gireesh Punathil.

Fixes: #25512
Co-authored-by: Gireesh Punathil <[email protected]>

PR-URL: #25896
Reviewed-By: Colin Ihrig <[email protected]>
Reviewed-By: Refael Ackermann <[email protected]>
Reviewed-By: Gireesh Punathil <[email protected]>
Reviewed-By: Eugene Ostroukhov <[email protected]>
MylesBorins pushed a commit that referenced this pull request May 16, 2019
@addaleax @MylesBorins
src: fix race condition in ~NodeTraceBuffer
bc5e04b 
Libuv does not guarantee that handles have their close
callbacks called in the order in which they were added
(and in fact, currently calls them in reverse order).

This patch ensures that the `flush_signal_` handle
is no longer in use (i.e. its close callback has already
been run) when we signal to the main thread that
`~NodeTraceBuffer` may be destroyed.

The same applies for `~NodeTraceWriter`.

Credit for debugging goes to Gireesh Punathil.

Fixes: #25512
Co-authored-by: Gireesh Punathil <[email protected]>

PR-URL: #25896
Reviewed-By: Colin Ihrig <[email protected]>
Reviewed-By: Refael Ackermann <[email protected]>
Reviewed-By: Gireesh Punathil <[email protected]>
Reviewed-By: Eugene Ostroukhov <[email protected]>
@BethGriggs BethGriggs mentioned this pull request May 16, 2019
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This was referenced May 29, 2019
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@snyk-bot snyk-bot mentioned this pull request Aug 11, 2020
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@gireeshpunathil gireeshpunathil gireeshpunathil approved these changes

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@refack refack refack approved these changes

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