[Run3 PromptReco] HLTPrescaleProvider::init() uses 4.9 MB memory per stream

[makortel]

From #46040 (comment)

The HLTPrescaleProvider::init() is called by pat::PATTriggerProducer::beginRun() and BPHMonitor::bookHistograms(), and ends up using 4.9 MB memory per stream (compare 1 thread/stream profile and 4 thread/stream profile. For an 8-thread/stream prompt reco job this would correspond to 39 MB.

Most of the memory is held by l1t::L1TGlobalUtil::retrieveL1Setup() (similarly to #46448). Does it need to be replicated among streams?

In addition, the l1t::L1TGlobalUtil::retrieveL1Setup() does 50 million memory allocations within its body, and nearly all of these come via the call from HLTPrescaleProvider::init().

[cmsbuild]

cms-bot internal usage

[cmsbuild]

A new Issue was created by @makortel.

@Dr15Jones, @antoniovilela, @makortel, @mandrenguyen, @rappoccio, @sextonkennedy, @smuzaffar can you please review it and eventually sign/assign? Thanks.

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[makortel]

assign hlt, l1

[cmsbuild]

New categories assigned: hlt,l1

@aloeliger,@epalencia,@Martin-Grunewald,@mmusich you have been requested to review this Pull request/Issue and eventually sign? Thanks

[makortel]

type performance-improvements

[Martin-Grunewald]

Probably not per stream, but https://cmssdt.cern.ch/lxr/source/HLTrigger/HLTcore/interface/HLTPrescaleProvider.h is a helper class, not a plugin itself, to be used as data member of plugins.

[makortel]

Both BPHMonitor and pat::PATTriggerProducer::beginRun() are stream modules, and have the HLTPrescaleProvider as data members

cmssw/DQMOffline/Trigger/plugins/BPHMonitor.cc

Line 142 in 8340b52

HLTPrescaleProvider* hltPrescale_;

cmssw/PhysicsTools/PatAlgos/plugins/PATTriggerProducer.cc

Line 118 in 8340b52

HLTPrescaleProvider hltPrescaleProvider_;

that then lead to the memory usage to increase with more streams.

Is HLTPrescaleProvider itself thread safe?

[makortel]

In addition, the l1t::L1TGlobalUtil::retrieveL1Setup() does 50 million memory allocations within its body, and nearly all of these come via the call from HLTPrescaleProvider::init().

[Martin-Grunewald]

The class was not written with thread safety in mind, and calls into L1T code.