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  1. ROOT
  2. ROOT-9556

[DF] Users might silently get wrong results when they process two trees as friends, one of which has been produced by a multi-thread Snapshot of the other

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    Details

    • Type: Bug
    • Status: Closed (View Workflow)
    • Priority: Critical
    • Resolution: Fixed
    • Affects Version/s: master
    • Fix Version/s: 6.22/00, 6.20/04
    • Component/s: RDataFrame
    • Labels:
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    • Environment:

      any

      Description

      We need at the very least to document this problem and possibly introduce diagnostics for this case. We might put a flag somewhere in the output file that specifies that it has been produced by a multi-thread Snapshot and therefore entries are scrambled w.r.t. the original dataset. TTree or RDataFrame could then check that flag and prompt a warning if things look fishy.

      One case in which this might result in undesired warnings is when two files that have been produced by two multi-thread Snapshots in the same event loop are used as friends of each other. To be checked if the on-disk dataset PID can help recognize this case.

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            • Assignee:
              eguiraud Enrico Guiraud
              Reporter:
              eguiraud Enrico Guiraud
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              • Created:
                Updated:
                Resolved: