Override the input branch settings for SIM AOD

[Dr15Jones]

PR description:

Having the input branches be fully split can save ~5% on the output file size.

PR validation:

Change based on the study described in #39449.

[Dr15Jones]

The effect is (probably) due to GenParticles being must easier to compress if the branch is fully split.

An alternative change could be to fully split the GenParticles in the GEN format.

[Dr15Jones]

please test

[cmsbuild]

+code-checks

Logs: https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-39457/32179

• This PR adds an extra 16KB to repository

[cmsbuild]

A new Pull Request was created by @Dr15Jones (Chris Jones) for master.

It involves the following packages:

• Configuration/EventContent (operations)

@perrotta, @rappoccio, @fabiocos, @davidlange6 can you please review it and eventually sign? Thanks.
@Martin-Grunewald, @missirol, @fabiocos this is something you requested to watch as well.
@perrotta, @dpiparo, @rappoccio you are the release manager for this.

cms-bot commands are listed here

[Dr15Jones]

please test

[cmsbuild]

+1

Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-88a02a/27686/summary.html
COMMIT: 6c17d95
CMSSW: CMSSW_12_6_X_2022-09-20-1100/el8_amd64_gcc10
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week1/cms-sw/cmssw/39457/27686/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: 51
• DQMHistoTests: Total histograms compared: 3621956
• DQMHistoTests: Total failures: 2
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 3621932
• DQMHistoTests: Total skipped: 22
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 50 files compared)
• Checked 212 log files, 49 edm output root files, 51 DQM output files
• TriggerResults: no differences found

[perrotta]

+1

• Reading in Study additional decrease in SIM AOD size #39449 (comment):
  • The default for the AOD event content is to preserve the branch splitting from the input file into the output file. This was probably initially done to allow fast cloning of those branches from the input to the output. But with our use of multi-threading, we already can not use fast cloning (as using multiple threads can cause the event order in the output file to differ from the event order in the input file).
  • By allowing the branches read/written from the input source to be fully split, the size of the 1000 event SIM AOD file decreased by 4.7 %.

[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 be automatically merged.