Fix a race condition in splitVertices [14.0.x]

[fwyzard]

PR description:

Add

alpaka::syncBlockThreads(acc);

at the end of the loop on the vertices to ensure that all threads are properly synchronised before resetting the shared memory.

Clean up the kernel to use the SoA accessors and the cms::alpakatools utilities.

PR validation:

Running the HLT with compute-sanitizer --tool=racecheck without this PR warns about a potential race condition in splitVertices().
This PR fixes the warning: see #44923 (comment).

Running the current online HLT menu over 20k events on top of CMSSW 14.0.13-patch2 does not result in any changes to the HLT results (see #45656 (comment)) and performance on GPU (see #45656 (comment)).

If this PR is a backport please specify the original PR and why you need to backport that PR. If this PR will be backported please specify to which release cycle the backport is meant for:

Backport of #45656 to 14.0.x for data taking.

[fwyzard]

type bugfix

[cmsbuild]

A new Pull Request was created by @fwyzard for CMSSW_14_0_X.

It involves the following packages:

• RecoTracker/PixelVertexFinding (reconstruction)

@cmsbuild, @jfernan2, @mandrenguyen can you please review it and eventually sign? Thanks.
@GiacomoSguazzoni, @JanFSchulte, @VinInn, @VourMa, @dgulhan, @felicepantaleo, @gpetruc, @missirol, @mmusich, @mtosi, @rovere this is something you requested to watch as well.
@antoniovilela, @mandrenguyen, @rappoccio, @sextonkennedy you are the release manager for this.

cms-bot commands are listed here

• Backported from Fix a race condition in splitVertices #45656

[cmsbuild]

cms-bot internal usage

[fwyzard]

@mmusich @AdrianoDee @missirol FYI, but also can you double check this ?

[cmsbuild]

Pull request #45655 was updated. @cmsbuild, @jfernan2, @mandrenguyen can you please check and sign again.

[fwyzard]

backport #45656

[fwyzard]

please test

[fwyzard]

enable gpu

[fwyzard]

please test

[cmsbuild]

+1

Size: This PR adds an extra 20KB to repository
Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-3401f4/40810/summary.html
COMMIT: 5408c0f
CMSSW: CMSSW_14_0_X_2024-08-06-1100/el8_amd64_gcc12
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week1/cms-sw/cmssw/45655/40810/install.sh to create a dev area with all the needed externals and cmssw changes.

Comparison Summary

Summary:

• You potentially added 6 lines to the logs
• Reco comparison results: 54 differences found in the comparisons
• DQMHistoTests: Total files compared: 49
• DQMHistoTests: Total histograms compared: 3449742
• DQMHistoTests: Total failures: 1238
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 3448484
• DQMHistoTests: Total skipped: 20
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 48 files compared)
• Checked 206 log files, 170 edm output root files, 49 DQM output files
• TriggerResults: no differences found

[AdrianoDee]

All the changes looks good to me

[mandrenguyen]

+reconstruction

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_14_0_X IBs (tests are also fine) and once validation in the development release cycle CMSSW_14_1_X is complete. This pull request will now be reviewed by the release team before it's merged. @antoniovilela, @sextonkennedy, @mandrenguyen, @rappoccio (and backports should be raised in the release meeting by the corresponding L2)

[antoniovilela]

+1