Bug fix: Issue with nVertices in L2NNTagTauProducer

[azotz]

PR description:

This pull request fixes a segmentation violation issue in L2NNTagTauProducer, which was occurring when nVertices is 0.

PR validation:

Code checks have been performed.

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

n/a

[cmsbuild]

@azotz, CMSSW_12_2_X branch is closed for direct updates. cms-bot is going to move this PR to master branch.
In future, please use cmssw master branch to submit your changes.

[cmsbuild]

+code-checks

Logs: https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-36318/27056

• This PR adds an extra 20KB to repository

[cmsbuild]

A new Pull Request was created by @azotz for master.

It involves the following packages:

• RecoTauTag/HLTProducers (hlt)

@cmsbuild, @missirol, @Martin-Grunewald can you please review it and eventually sign? Thanks.
@silviodonato, @mbluj, @azotz 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

[missirol]

type bugfix

[missirol]

@azotz

Could you please give a bit more info on the problem? Where exactly was the seg-fault occurring, and how was this spotted? Thanks.

[missirol]

please test

[kandrosov]

@azotz

Could you please give a bit more info on the problem? Where exactly was the seg-fault occurring, and how was this spotted? Thanks.

The seg-fault was occurring in this line

cmssw/RecoTauTag/HLTProducers/src/L2TauTagNNProducer.cc

Line 619 in 61a8f90

auto const minFOM_fromFrac = pTSquaredSum[sortIdxs.front()] * fractionSumPt2_;

When patavtx_soa.nvFinal==0, sortIdxs is empty and sortIdxs.front() is undefined.
We only observe nvFinal==0 when running on data (for rates estimation), for MC nvFinal is always greater than 0. That is why we didn't spot this error during the initial deployment.

[cmsbuild]

+1

Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-31aeb3/20907/summary.html
COMMIT: 61a8f90
CMSSW: CMSSW_12_2_X_2021-12-01-1100/slc7_amd64_gcc900
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week1/cms-sw/cmssw/36318/20907/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: 41
• DQMHistoTests: Total histograms compared: 3041955
• DQMHistoTests: Total failures: 0
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 3041933
• DQMHistoTests: Total skipped: 22
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 40 files compared)
• Checked 175 log files, 37 edm output root files, 41 DQM output files
• TriggerResults: no differences found

[missirol]

+hlt

• simple bugfix to a plugin designed for HLT which is not currently used in any production workflow, nor any unit test

[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