No need to explicitly delete the pre-existsing histogram for ROOT >= 6.38

[smuzaffar]

Fixes #49309
This change needs a newer ROOT 6.38
With latest root change root-project/root@17a49d1 , to avoid memory leak, SetHistogram now deletes pre-existing histogram. This change propose to call runGraph->GetHistogram()->Delete(); only for old versions of root.

[cmsbuild]

cms-bot internal usage

[cmsbuild]

+code-checks

Logs: https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-49319/46683

[cmsbuild]

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

It involves the following packages:

• Alignment/OfflineValidation (alca)

@arunhep, @atpathak, @cmsbuild, @perrotta can you please review it and eventually sign? Thanks.
@mmusich, @rsreds, @tlampen, @tocheng, @yuanchao 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

[smuzaffar]

please test

it should work for existsing root version of default IBs

[perrotta]

Isn't the fix applied since root version 6.38.00?

• TGraph::SetHistogram() can leak memory root-project/root#20252
• root-project/root@17a49d1

[smuzaffar]

thanks @perrotta , yes it is applied for root 6.38.00 .

[cmsbuild]

+code-checks

Logs: https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-49319/46686

[cmsbuild]

Pull request #49319 was updated. @arunhep, @atpathak, @cmsbuild, @perrotta can you please check and sign again.

[smuzaffar]

please test

[cmsbuild]

+1

Size: This PR adds an extra 32KB to repository
Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-8ad1e7/49268/summary.html
COMMIT: c40a569
CMSSW: CMSSW_16_0_X_2025-11-04-2300/el8_amd64_gcc13
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week0/cms-sw/cmssw/49319/49268/install.sh to create a dev area with all the needed externals and cmssw changes.

Comparison Summary

Summary:

• You potentially added 5 lines to the logs
• Reco comparison results: 6 differences found in the comparisons
• DQMHistoTests: Total files compared: 51
• DQMHistoTests: Total histograms compared: 3939953
• DQMHistoTests: Total failures: 85
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 3939848
• DQMHistoTests: Total skipped: 20
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 50 files compared)
• Checked 218 log files, 188 edm output root files, 51 DQM output files
• TriggerResults: no differences found

[smuzaffar]

@cms-sw/alca-l2 , can you please review this change?

[perrotta]

@cms-sw/alca-l2 , can you please review this change?

@smuzaffar I am perfectly fine with this fix,
I was waiting for it being tested in the relevant IBs, supposedly with cms-sw/cmsdist#10176 : shouldn't I wait for the tests of that cmsdist PR to succeed before signing? (I tested this fix directly in root without this PR, and it works: if you want to have it merged since now, I could rely on that side validation to sign it)

[perrotta]

+alca

• As far as I can see from the results of the latest tests in [ROOT6] Updated root to tip of branch master and used newer 6.39.1 version cmsdist#10176 (comment), while other problems persist with the move to root 6.39.1, the particolar one addressed here gets fixed by this PR. It can therefore get merged since now in the master branch of the release.

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

[mandrenguyen]

+1

[iarspider]

Hi @smuzaffar ,

the test still failed in CMSSW_16_0_ROOT6_X_2025-11-09-2300 that has this PR. I think we also shouldn't do runGraph->SetHistogram(nullptr); with new ROOT?

[smuzaffar]

@iarspider , do we have root >= 6.38 in root6 ibs? If not then test will keep on failing