[14.0.X] MultiTrajectoryStateAssembler: protect removeWrongPz when average pZ sign is identically 0

[mmusich]

backport of #45646

PR description:

This PR is meant as a fix for the situation that occurred in online HLT operations and lead to #45639.
As explained in detailed #45639 (comment), in this event, some states have positive pz-sign, and some states have negative pz-sign, which is a problem.
The chain of calls is the following: GsfMultiStateUpdator calls MultiTrajectoryStateAssembler::combinedState() , which in turn calls MultiTrajectoryStateAssembler::prepareCombinedState(). At this stage, the algo tries to fix the problem by calling removeWrongPz(). In most cases removeWrongPz will solve the issue.
In one special case , where meanPz=0, it will not be able to solve the issue and it will let the charged-flipped states pass which will create the crash later on, where there is another check of pz-sign.
This PR circumvents the issue by explicitly logging an error when this happens, clear the states vector and then do an early return.

PR validation:

Tested in CMSSW_14_0_13_MULTIARCH + this commit mmusich@24d4fd2 with the reproducer at #45639 (comment):

#!/bin/bash -ex

# CMSSW_14_0_13_MULTIARCHS

hltGetConfiguration run:384069 \
--globaltag 140X_dataRun3_HLT_v3 \
--data \
--no-prescale \
--no-output \
--max-events -1 \
--input '/store/group/tsg/FOG/error_stream_root/run384069/run384069_ls0689_index000033_fu-c2b04-35-01_pid2378323.root,/store/group/tsg/FOG/error_stream_root/run384069/run384069_ls0689_index000067_fu-c2b0
4-35-01_pid2378323.root' > hlt.py

cat <<@EOF >> hlt.py
del process.MessageLogger
process.load('FWCore.MessageService.MessageLogger_cfi')  
process.options.wantSummary = True
process.options.numberOfThreads = 1
process.options.numberOfStreams = 0
@EOF

cmsRun hlt.py &> hlt.log

and observed no crash.

N.B.

It's worth noting that the crash doesn't appear to start with in CMSSW_14_0_13 (tout-cout) , so it looks like the MULTIARCHS variant (hence x86-64-v3 micro-architecture) is triggering the problem in the first place, see #45639 (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:

Verbatim backport of #45646 for 2024 online HLT data-taking puroposes.

[cmsbuild]

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

It involves the following packages:

• TrackingTools/GsfTools (reconstruction)

@cmsbuild, @jfernan2, @mandrenguyen can you please review it and eventually sign? Thanks.
@GiacomoSguazzoni, @JanFSchulte, @VinInn, @VourMa, @bellan, @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 MultiTrajectoryStateAssembler: protect removeWrongPz when average pZ sign is identically 0 #45646

[cmsbuild]

cms-bot internal usage

[mmusich]

@cmsbuild, please test

[cmsbuild]

+1

Size: This PR adds an extra 16KB to repository
Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-073c1b/40796/summary.html
COMMIT: bbb5bdb
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/45647/40796/install.sh to create a dev area with all the needed externals and cmssw changes.

Comparison Summary

Summary:

• You potentially added 2 lines to the logs
• Reco comparison results: 55 differences found in the comparisons
• DQMHistoTests: Total files compared: 49
• DQMHistoTests: Total histograms compared: 3449742
• DQMHistoTests: Total failures: 1215
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 3448507
• 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

[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. @sextonkennedy, @mandrenguyen, @antoniovilela, @rappoccio (and backports should be raised in the release meeting by the corresponding L2)

[mandrenguyen]

+1