[net] TParallelMergingFile: don't rely on nbytes for UploadAndReset() #20211
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The `nbytes` value returned by TDirectoryFile::Write() is only > 0 if we write at least one TObject to the file, which is not the case for non-TObject-based objects that handle their own writing (e.g. RNTuple through RMiniFile). This means that if we write only non-TObjects in a TParallelMergingFile we will never call UploadAndReset() by only checking nbytes. With this PR, we instead use GetBytesWritten() to check if anything gets written by TDirectoryFile::Write(), which works even in case of non- TObjects.
silverweed
requested review from
enirolf,
hahnjo,
jblomer,
pcanal and
vepadulano
Test Results 21 files 21 suites 3d 10h 25m 16s ⏱️ Results for commit 9194c07. |
jblomer
reviewed
Oct 29, 2025
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The
nbytesvalue returned by TDirectoryFile::Write() is only > 0 if we write at least one TObject to the file, which is not the case for non-TObject-based objects that handle their own writing (e.g. RNTuple through RMiniFile).This means that if we write only non-TObjects in a TParallelMergingFile we will never call UploadAndReset() by only checking nbytes. With this PR, we instead use GetBytesWritten() to check if anything gets written by TDirectoryFile::Write(), which works even in case of non- TObjects.
cc @amete - this should fix one of the issues you observed with your parallel file merger when you only merge RNTuples.