[16_0_X] Add safeguard in final step of Alpaka PF multi-depth clustering when 0 clusters are present

[jsamudio]

PR description:

This PR prevents a crash in the final step of Alpaka PF multi-depth clustering under the special case of 0 clusters which would occur when there are 0 valid rechits in an event. The implementation is similar to that of the layer clustering.

PR validation:

PR was validated using a customized HLT menu running on error stream data that contained a special event.

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:

Verbatim backport of #50603 for CMSSW_16_0_X

@alexstrel @fwyzard

[cmsbuild]

A new Pull Request was created by @jsamudio for CMSSW_16_0_X.

It involves the following packages:

• RecoParticleFlow/PFClusterProducer (reconstruction)

@Moanwar, @cmsbuild, @jfernan2, @mandrenguyen, @srimanob can you please review it and eventually sign? Thanks.
@felicepantaleo, @hatakeyamak, @lgray, @mmarionncern, @rovere, @sameasy, @seemasharmafnal this is something you requested to watch as well.
@ftenchini, @mandrenguyen, @sextonkennedy you are the release manager for this.

cms-bot commands are listed here

• Backported from Add safeguard in final step of Alpaka PF multi-depth clustering when 0 clusters are present #50603

[cmsbuild]

cms-bot internal usage

[Moanwar]

enable gpu

[Moanwar]

@cmsbuild please test

[mmusich]

backport of #50603

[mmusich]

type pf

[mmusich]

type bug-fix

[cmsbuild]

+1

Size: This PR adds an extra 20KB to repository
Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-5d5a2a/52364/summary.html
COMMIT: 849764d
CMSSW: CMSSW_16_0_X_2026-03-31-1100/el8_amd64_gcc13
Additional Tests: GPU,AMD_MI300X,AMD_W7900,NVIDIA_H100,NVIDIA_L40S
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week1/cms-sw/cmssw/50604/52364/install.sh to create a dev area with all the needed externals and cmssw changes.

Comparison Summary

The workflows 2023.0020001 have different files in step1_dasquery.log than the ones found in the baseline. You may want to check and retrigger the tests if necessary. You can check it in the "files" directory in the results of the comparisons

Summary:

• You potentially removed 5 lines from the logs
• ROOTFileChecks: Some differences in event products or their sizes found
• Reco comparison results: 3923 differences found in the comparisons
• DQMHistoTests: Total files compared: 53
• DQMHistoTests: Total histograms compared: 4168215
• DQMHistoTests: Total failures: 5296
• DQMHistoTests: Total nulls: 83
• DQMHistoTests: Total successes: 4162816
• DQMHistoTests: Total skipped: 20
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 20.976 KiB( 52 files compared)
• DQMHistoSizes: changed ( 2023.0020001 ): 20.484 KiB Hcal/DigiRunHarvesting
• DQMHistoSizes: changed ( 2023.0020001 ): 0.539 KiB RPC/DCSInfo
• DQMHistoSizes: changed ( 2023.0020001 ): -0.043 KiB JetMET/SUSYDQM
• DQMHistoSizes: changed ( 2023.0020001 ): -0.005 KiB SiStrip/MechanicalView
• Checked 227 log files, 198 edm output root files, 53 DQM output files
• TriggerResults: found differences in 1 / 51 workflows

AMD_MI300X Comparison Summary

Summary:

• No significant changes to the logs found
• Reco comparison results: 240 differences found in the comparisons
• DQMHistoTests: Total files compared: 11
• DQMHistoTests: Total histograms compared: 150195
• DQMHistoTests: Total failures: 31265
• DQMHistoTests: Total nulls: 10
• DQMHistoTests: Total successes: 118920
• DQMHistoTests: Total skipped: 0
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 10 files compared)
• Checked 42 log files, 45 edm output root files, 11 DQM output files
• TriggerResults: found differences in 1 / 10 workflows

AMD_W7900 Comparison Summary

Summary:

• You potentially added 11 lines to the logs
• Reco comparison results: 255 differences found in the comparisons
• DQMHistoTests: Total files compared: 11
• DQMHistoTests: Total histograms compared: 150195
• DQMHistoTests: Total failures: 30898
• DQMHistoTests: Total nulls: 6
• DQMHistoTests: Total successes: 119291
• DQMHistoTests: Total skipped: 0
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 10 files compared)
• Checked 42 log files, 45 edm output root files, 11 DQM output files
• TriggerResults: no differences found

NVIDIA_H100 Comparison Summary

Summary:

• You potentially added 16 lines to the logs
• Reco comparison results: 253 differences found in the comparisons
• DQMHistoTests: Total files compared: 11
• DQMHistoTests: Total histograms compared: 150195
• DQMHistoTests: Total failures: 29183
• DQMHistoTests: Total nulls: 10
• DQMHistoTests: Total successes: 121002
• DQMHistoTests: Total skipped: 0
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 10 files compared)
• Checked 42 log files, 45 edm output root files, 11 DQM output files
• TriggerResults: found differences in 1 / 10 workflows

NVIDIA_L40S Comparison Summary

Summary:

• You potentially added 41 lines to the logs
• Reco comparison results: 241 differences found in the comparisons
• DQMHistoTests: Total files compared: 11
• DQMHistoTests: Total histograms compared: 150195
• DQMHistoTests: Total failures: 29367
• DQMHistoTests: Total nulls: 8
• DQMHistoTests: Total successes: 120820
• DQMHistoTests: Total skipped: 0
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 10 files compared)
• Checked 42 log files, 45 edm output root files, 11 DQM output files
• TriggerResults: no differences found

[cmsbuild]

Pull request #50604 was updated. @Moanwar, @cmsbuild, @jfernan2, @mandrenguyen, @srimanob can you please check and sign again.

[fwyzard]

please test

[fwyzard]

+heterogeneous

[cmsbuild]

+1

Size: This PR adds an extra 20KB to repository
Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-5d5a2a/52404/summary.html
COMMIT: b3414e9
CMSSW: CMSSW_16_0_X_2026-04-01-1100/el8_amd64_gcc13
Additional Tests: GPU,AMD_MI300X,AMD_W7900,NVIDIA_H100,NVIDIA_L40S
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week1/cms-sw/cmssw/50604/52404/install.sh to create a dev area with all the needed externals and cmssw changes.

Comparison Summary

Summary:

• No significant changes to the logs found
• Reco comparison results: 0 differences found in the comparisons
• DQMHistoTests: Total files compared: 53
• DQMHistoTests: Total histograms compared: 4168215
• DQMHistoTests: Total failures: 72
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 4168123
• DQMHistoTests: Total skipped: 20
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 52 files compared)
• Checked 227 log files, 198 edm output root files, 53 DQM output files
• TriggerResults: no differences found

AMD_MI300X Comparison Summary

Summary:

• You potentially added 7 lines to the logs
• Reco comparison results: 254 differences found in the comparisons
• DQMHistoTests: Total files compared: 11
• DQMHistoTests: Total histograms compared: 150195
• DQMHistoTests: Total failures: 31248
• DQMHistoTests: Total nulls: 10
• DQMHistoTests: Total successes: 118937
• DQMHistoTests: Total skipped: 0
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 10 files compared)
• Checked 42 log files, 45 edm output root files, 11 DQM output files
• TriggerResults: found differences in 1 / 10 workflows

AMD_W7900 Comparison Summary

Summary:

• You potentially removed 6 lines from the logs
• Reco comparison results: 254 differences found in the comparisons
• DQMHistoTests: Total files compared: 11
• DQMHistoTests: Total histograms compared: 150195
• DQMHistoTests: Total failures: 27536
• DQMHistoTests: Total nulls: 12
• DQMHistoTests: Total successes: 122647
• DQMHistoTests: Total skipped: 0
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 10 files compared)
• Checked 42 log files, 45 edm output root files, 11 DQM output files
• TriggerResults: found differences in 2 / 10 workflows

NVIDIA_H100 Comparison Summary

Summary:

• You potentially removed 7 lines from the logs
• Reco comparison results: 224 differences found in the comparisons
• DQMHistoTests: Total files compared: 11
• DQMHistoTests: Total histograms compared: 150195
• DQMHistoTests: Total failures: 37506
• DQMHistoTests: Total nulls: 7
• DQMHistoTests: Total successes: 112682
• DQMHistoTests: Total skipped: 0
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 10 files compared)
• Checked 42 log files, 45 edm output root files, 11 DQM output files
• TriggerResults: no differences found

NVIDIA_L40S Comparison Summary

Summary:

• You potentially added 21 lines to the logs
• Reco comparison results: 247 differences found in the comparisons
• DQMHistoTests: Total files compared: 11
• DQMHistoTests: Total histograms compared: 150195
• DQMHistoTests: Total failures: 29358
• DQMHistoTests: Total nulls: 15
• DQMHistoTests: Total successes: 120822
• DQMHistoTests: Total skipped: 0
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 10 files compared)
• Checked 42 log files, 45 edm output root files, 11 DQM output files
• TriggerResults: no differences found

[mandrenguyen]

urgent

[mmusich]

@cms-sw/reconstruction-l2 kind ping

[mandrenguyen]

@cms-sw/reconstruction-l2 kind ping

To be transparent, I signed for them for the master version in the interest of getting this in the 1100 IB. Still if reco can have a look and make sure they ok with it, we can merge this after we clear the 1100 IB, and build the patch tonight.

[Moanwar]

+1

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_16_0_X IBs (tests are also fine) and once validation in the development release cycle CMSSW_16_1_X is complete. This pull request will now be reviewed by the release team before it's merged. @ftenchini, @mandrenguyen, @sextonkennedy (and backports should be raised in the release meeting by the corresponding L2)