Prevent VirtualJetProducer from wasting time on setup if input empty

[rappoccio]

From @sethzenz : optimize the VirtualJetProducer for H->gammagamma analysis when multiple vertex hypotheses are used, but many inputs are empty.

[cmsbuild]

A new Pull Request was created by @rappoccio for CMSSW_7_6_X.

Prevent VirtualJetProducer from wasting time on setup if input empty

It involves the following packages:

RecoJets/JetProducers

@cmsbuild, @cvuosalo, @slava77 can you please review it and eventually sign? Thanks.
@TaiSakuma, @jdolen, @ahinzmann, @yslai, @nhanvtran, @schoef, @mariadalfonso this is something you requested to watch as well.
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[slava77]

@cmsbuild please test

[cmsbuild]

The tests are being triggered in jenkins.
https://cmssdt.cern.ch/jenkins/job/ib-any-integration/8921/console

[cmsbuild]

+1
Tested at: a528c4f
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-11820/8921/summary.html

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-11820/8921/summary.html

[lgray]

@rappoccio @sethzenz Wouldn't it be better to put a single if statement later to skip the expensive stuff instead of three short circuits?

[cvuosalo]

+1

For #11820 a528c4f

Adding skipping of empty inputs to save time in VirtualJetProducer. There should be no change in monitored quantities.

The code changes are satisfactory, and Jenkins tests against baseline CMSSW_7_6_X_2015-10-15-1100 show no significant differences, as expected. An extended test of workflow 134.702_RunDoubleEG2015B with 70 events against baseline CMSSW_7_6_X_2015-10-14-1600 also shows no significant differences and no significant change in timing, as shown below.

Baseline
Max VSIZ 2610.18 on evt 60 ; max RSS 2164.29 on evt 49
Time av 6.69834 s/evt   max 32.8115 s on evt 1
M1 Time av 6.31989 s/evt   max 10.5374 s on evt 47
M8 Time av 6.16307 s/evt   max 10.5374 s on evt 47

PR
Max VSIZ 2610.18 on evt 49 ; max RSS 2199.28 on evt 69
Time av 6.66179 s/evt   max 32.8522 s on evt 1
M1 Time av 6.28222 s/evt   max 10.3564 s on evt 47
M8 Time av 6.10679 s/evt   max 10.3564 s on evt 47

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_7_6_X IBs (tests are also fine). This pull request requires discussion in the ORP meeting before it's merged. @davidlange6, @Degano, @smuzaffar

[davidlange6]

+1