PodioOutput saves metadata of droped collections into the ROOT file

[kjvbrt]

When collection is dropped in PodioOutput its metadata are saved regardless.

• OS version: e.g. centos7
• Package version: key4hep-nightlies
• Reproduced by: podio-dump on generated file crashes when dropped collection is encountered
• Example file generator: https://github.com/HEP-FCC/k4RecCalorimeter/blob/main/RecFCCeeCalorimeter/tests/options/runCaloSim.py
• Expected behaviour: Metadata of dropped collections are not saved

[tmadlener]

Could you also post the backtrace of the podio-dump crash? Have you also tried what happens if you don't drop any collections at all in the podio output?

[tmadlener]

I can reproduce this. I am not yet entirely sure if this is an issue in the ROOTLegacyReader that is invoked for reading the produced files or if this is truly an issue of the PodioOutput algorithm.

[kjvbrt]

Could you also post the backtrace of the podio-dump crash? Have you also tried what happens if you don't drop any collections at all in the podio output?

crash.txt

If none of the collections is dropped, then there is no crash.

[tmadlener]

Can you check this with reading the files using the ROOTReader and the EventStore from podio? (I.e. the legacy way to do this). If that works then we would now it is most likely a problem in podio and not in the framework.

[kjvbrt]

Reading the files using ROOTReader produces following errors, but does not crash.

PODIO: Reconstructing CollectionTypeInfo branch from other sources in file: 'output_fullCalo_SimAndDigi.root'
Problems reconstructing collection info for collection: 'ECalBarrelPositionedHits'
Problems reconstructing collection info for collection: 'ECalEndcapPositionedHits'
Problems reconstructing collection info for collection: 'HCalBarrelPositionedHits'
Problems reconstructing collection info for collection: 'ECalBarrelCellsStep1'
Problems reconstructing collection info for collection: 'ECalBarrelCellsStep2'
Problems reconstructing collection info for collection: 'HCalBarrelCells'
Problems reconstructing collection info for collection: 'emptyCaloCells'
Problems reconstructing collection info for collection: 'CaloClusterCells'

[kjvbrt]

As the k4RecCalorimeter has been also updated to use frames HEP-FCC/k4RecCalorimeter#41, HEP-FCC/k4RecCalorimeter#43 the issue is no longer present in the nightlies and I get the expected output with podio-dump.

If however one generates root file in the stable stack and then tries to read the file with podio-dump the crash still happens at the same place:

$ podio-dump output_fullCalo_SimAndDigi.root 
input file: output_fullCalo_SimAndDigi.root (this is a legacy file!)

datamodel model definitions stored in this file: 

Frame categories in this file:
Name                 Entries   
-------------------------------
events               2         

 *** Break *** segmentation violation

.
.
.

#9  0x00007f27571e496c in podio::ROOTLegacyReader::getCollectionBuffers(std::pair<std::__cxx11::basic_strin
g<char, std::char_traits<char>, std::allocator<char> >, std::tuple<std::__cxx11::basic_string<char, std::ch
ar_traits<char>, std::allocator<char> >, bool, unsigned int, unsigned long> > const&) () from /cvmfs/sw-nig
htlies.hsf.org/key4hep/releases/2023-09-18/x86_64-centos7-gcc12.2.0-opt/podio/d402f747877239aaedefe993856e2
6749c91bea3=develop-ivgpec/lib64/libpodioRootIO.so
#10 0x00007f27571e6af8 in podio::ROOTLegacyReader::readEntry() () from /cvmfs/sw-nightlies.hsf.org/key4hep/
releases/2023-09-18/x86_64-centos7-gcc12.2.0-opt/podio/d402f747877239aaedefe993856e26749c91bea3=develop-ivg
pec/lib64/libpodioRootIO.so
#11 0x00007f27571e780f in podio::ROOTLegacyReader::readEntry(std::__cxx11::basic_string<char, std::char_tra
its<char>, std::allocator<char> > const&, unsigned int) () from /cvmfs/sw-nightlies.hsf.org/key4hep/release
s/2023-09-18/x86_64-centos7-gcc12.2.0-opt/podio/d402f747877239aaedefe993856e26749c91bea3=develop-ivgpec/lib
64/libpodioRootIO.so

[tmadlener]

This should no longer be the case since the switch to the Frame based I/O in #100. Please re-open if there are still issues.