fix undefined behavior in MultiTrackValidator

[mmusich]

PR description:

Aim of this PR is to fix the undefined behavior reported at #35037.
When the input track collection is empty, just return instead of creating arrays of size 0.

PR validation:

Run workflow 11603.0 with this branch on top of CMSSW_12_1_UBSAN_X_2021-08-27-2300 and didn't observe runtime errors linked to MultiTrackValidator.

if this PR is a backport please specify the original PR and why you need to backport that PR:

N/A

Cc:
@vberta @mtosi FYI

[cmsbuild]

+code-checks

Logs: https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-35086/24966

• This PR adds an extra 24KB to repository

[cmsbuild]

A new Pull Request was created by @mmusich (Marco Musich) for master.

It involves the following packages:

• Validation/RecoTrack (dqm)

@andrius-k, @kmaeshima, @ErnestaP, @ahmad3213, @cmsbuild, @jfernan2, @rvenditti can you please review it and eventually sign? Thanks.
@felicepantaleo, @GiacomoSguazzoni, @JanFSchulte, @rovere, @VinInn, @ebrondol, @wmtford, @mmusich, @mtosi, @dgulhan this is something you requested to watch as well.
@perrotta, @dpiparo, @qliphy you are the release manager for this.

cms-bot commands are listed here

[mrodozov]

please test

[mrodozov]

please test

[cmsbuild]

+1

Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-d54118/18156/summary.html
COMMIT: ec0f51a
CMSSW: CMSSW_12_1_X_2021-08-30-2300/slc7_amd64_gcc900
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week0/cms-sw/cmssw/35086/18156/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: 6 differences found in the comparisons
• DQMHistoTests: Total files compared: 39
• DQMHistoTests: Total histograms compared: 3000404
• DQMHistoTests: Total failures: 11
• DQMHistoTests: Total nulls: 1
• DQMHistoTests: Total successes: 3000370
• DQMHistoTests: Total skipped: 22
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: -0.004 KiB( 38 files compared)
• DQMHistoSizes: changed ( 312.0 ): -0.004 KiB MessageLogger/Warnings
• Checked 165 log files, 37 edm output root files, 39 DQM output files
• TriggerResults: no differences found

[mmusich]

@mrodozov I don't see the output of wf 11603 in the logs.
Might it be that #35086 (comment) wasn't picked up?

[mrodozov]

11603 will be available only for the second test and the bot will comment with another link for it,
which is also nearly finished if you look the status section below
cms/35086/UBSAN/slc7_amd64_gcc10/comparison Pending — Running default comparison

[cmsbuild]

+1

Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-d54118/18157/summary.html
COMMIT: ec0f51a
CMSSW: CMSSW_12_1_UBSAN_X_2021-08-27-2300/slc7_amd64_gcc10
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week1/cms-sw/cmssw/35086/18157/install.sh to create a dev area with all the needed externals and cmssw changes.

The following merge commits were also included on top of IB + this PR after doing git cms-merge-topic:

• @perrotta Get rid of a dead increment in SiStripMonitorClient #35059
• @afiqaize address UB in EnergyUncertaintyPhotonSpecific.cc #35045
• @iarspider [GCC11] Fix warnings: loop variable binds to a temporary #35044
• @perrotta Initalize flag in SiStripQualityChecker #35060
• @iarspider [GCC11] Fix warning: loop variable binds to temporary #35041
• @fabferro PPS: solving issue 35033 for CTPPSPixelRecHits #35053
• @Sam-Harper Adding protections to PATTriggerProducer when the path has zero filters: 12_1 #35043
• @fabiocos MTD reconstruction: replace specific forward layer with the general mother class #35062
• @smorovic DataFormats/FEDRawData UBSAN warning fixed #35039
• @mrodozov Initialize member var in class DQClient #35063
• @bsunanda Run3-sim104 Update the tools to investigate geometry setups #35015
• @czangela Follow up to PR review of CPEFast to better reproduce Generic and #34400 #34882
• @makortel Migrate some modules in SimCalorimetry to esConsumes #34995

You can see more details here:
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-d54118/18157/git-recent-commits.json
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-d54118/18157/git-merge-result

Comparison Summary

@slava77 comparisons for the following workflows were not done due to missing matrix map:

• /data/cmsbld/jenkins/workspace/compare-root-files-short-matrix/data/PR-d54118/11603.0_SingleElectronPt1000+2021+SingleElectronPt1000_pythia8_GenSim+Digi+Reco+HARVEST+ALCA

Summary:

• You potentially added 21236 lines to the logs
• ROOTFileChecks: Some differences in event products or their sizes found
• Reco comparison results: 61734 differences found in the comparisons
• DQMHistoTests: Total files compared: 39
• DQMHistoTests: Total histograms compared: 3000352
• DQMHistoTests: Total failures: 266147
• DQMHistoTests: Total nulls: 18
• DQMHistoTests: Total successes: 2734165
• DQMHistoTests: Total skipped: 22
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.252 KiB( 38 files compared)
• DQMHistoSizes: changed ( 136.731,... ): 0.004 KiB JetMET/SUSYDQM
• DQMHistoSizes: changed ( 250202.181 ): -0.064 KiB SiStrip/MechanicalView
• DQMHistoSizes: changed ( 25202.0 ): 0.308 KiB SiStrip/MechanicalView
• Checked 165 log files, 37 edm output root files, 39 DQM output files
• TriggerResults: found differences in 13 / 38 workflows

[jfernan2]

please test

Trying to get a clean comparison environment

[cmsbuild]

+1

Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-d54118/18347/summary.html
COMMIT: ec0f51a
CMSSW: CMSSW_12_1_UBSAN_X_2021-09-03-2300/slc7_amd64_gcc10
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week0/cms-sw/cmssw/35086/18347/install.sh to create a dev area with all the needed externals and cmssw changes.

Comparison Summary

The workflows 140.53 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

@slava77 comparisons for the following workflows were not done due to missing matrix map:

• /data/cmsbld/jenkins/workspace/compare-root-files-short-matrix/data/PR-d54118/11603.0_SingleElectronPt1000+2021+SingleElectronPt1000_pythia8_GenSim+Digi+Reco+HARVEST+ALCA

Summary:

• You potentially added 21152 lines to the logs
• ROOTFileChecks: Some differences in event products or their sizes found
• Reco comparison results: 62877 differences found in the comparisons
• DQMHistoTests: Total files compared: 39
• DQMHistoTests: Total histograms compared: 3000491
• DQMHistoTests: Total failures: 215791
• DQMHistoTests: Total nulls: 37
• DQMHistoTests: Total successes: 2784641
• DQMHistoTests: Total skipped: 22
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: -45.451 KiB( 38 files compared)
• DQMHistoSizes: changed ( 136.731,... ): 0.004 KiB JetMET/SUSYDQM
• DQMHistoSizes: changed ( 140.53 ): -44.531 KiB Hcal/DigiRunHarvesting
• DQMHistoSizes: changed ( 140.53 ): -1.172 KiB RPC/DCSInfo
• DQMHistoSizes: changed ( 250202.181 ): -0.064 KiB SiStrip/MechanicalView
• DQMHistoSizes: changed ( 25202.0 ): 0.308 KiB SiStrip/MechanicalView
• Checked 165 log files, 37 edm output root files, 39 DQM output files
• TriggerResults: found differences in 13 / 38 workflows

[mmusich]

@jfernan2 please hold this one: I have still to address #35037 (comment)

[mrodozov]

for the comparison I'll suggest to run it against the default IB.
If @mmusich says the runtime error is not there I trust it's not there

[mmusich]

test parameters:

[mmusich]

please test

[mmusich]

@jfernan2 the last two instructions should test against the default build (I hope)

[mrodozov]

please test

[mrodozov]

I removed the prev test params, so yes it should start against the default

[cmsbuild]

+1

Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-d54118/18600/summary.html
COMMIT: d7af8e6
CMSSW: CMSSW_12_1_X_2021-09-13-2300/slc7_amd64_gcc900
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week0/cms-sw/cmssw/35086/18600/install.sh to create a dev area with all the needed externals and cmssw changes.

Comparison Summary

The workflows 140.53 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:

• No significant changes to the logs found
• Reco comparison results: 1303 differences found in the comparisons
• DQMHistoTests: Total files compared: 39
• DQMHistoTests: Total histograms compared: 3001001
• DQMHistoTests: Total failures: 3677
• DQMHistoTests: Total nulls: 19
• DQMHistoTests: Total successes: 2997283
• DQMHistoTests: Total skipped: 22
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: -45.703 KiB( 38 files compared)
• DQMHistoSizes: changed ( 140.53 ): -44.531 KiB Hcal/DigiRunHarvesting
• DQMHistoSizes: changed ( 140.53 ): -1.172 KiB RPC/DCSInfo
• Checked 165 log files, 37 edm output root files, 39 DQM output files
• TriggerResults: no differences found

[jfernan2]

+1

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next master IBs (tests are also fine). This pull request will now be reviewed by the release team before it's merged. @perrotta, @dpiparo, @qliphy (and backports should be raised in the release meeting by the corresponding L2)

[perrotta]

+1