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  1. ROOT
  2. ROOT-10927

Dramatic increase of memory usage while reading trees containing histograms

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      Merging files in 6.20 and 6.22 implies a much higher memory usage than in 6.18. This is a serious problem for CMS production, e.g. when it comes to merge monitoring histograms. This is a standalone reproducer by Marcel Schneider which runs out of the box on lxplus: https://gist.github.com/dpiparo/ac89c4303e622b1b307c6d6c04013cf0

       source /cvmfs/sft.cern.ch/lcg/app/releases/ROOT/6.18.00/x86_64-centos7-gcc48-opt/bin/thisroot.sh
       root -b -q repro.C
       echo 6.18 res memory = 1879.34 Mbytes
       
       source /cvmfs/sft.cern.ch/lcg/app/releases/ROOT/6.20.00/x86_64-centos7-gcc48-opt/bin/thisroot.sh
       root -b -q repro.C
       echo 6.20 res memory = 2951.23 Mbytes
       
       source /cvmfs/sft.cern.ch/lcg/app/releases/ROOT/6.22.00/x86_64-centos7-gcc48-opt/bin/thisroot.sh
       root -b -q repro.C
       echo 6.22 res memory = 2966.5 Mbytes
      

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            • Assignee:
              pcanal Philippe Canal
              Reporter:
              dpiparo Danilo Piparo
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