Converters do not work with IOSvc

[tmadlener]

The converters still partially refer to the PodioDataSvc explicitly and will fail with a segmentation violation when used with the IOSvc.

[tmadlener]

This probably needs a bit more work, because currently the PodioDataSvc is pretty ingrained in some places, and for some things I am not sure if they will work with the IOSvc.

The LcioEventAlgo currently puts an LCEventWrapper into the eventSvc

k4MarlinWrapper/k4MarlinWrapper/src/components/LcioEventAlgo.cpp

Lines 67 to 68 in 3165e40

	auto myEvWr = new LCEventWrapper(std::move(theEvent));
	const StatusCode sc = eventSvc()->registerObject("/Event/LCEvent", myEvWr);

Does this still work with the IOSvc? @jmcarcell IIUC, this should still work, but the LCEvent will not be available for our functional algorithms, right?

For the converters it should be possible to put in place checks that check the IOSvc, resp. MetadataSvc and the PodioDataSvc.

[tmadlener]

As discussed during the EDM4hep meeting, we will not put too much effort into supporting IOSvc with the k4MarlinWrapper, because that is intended mainly for multithreaded usage, and only very few Marlin processors are actually thread safe. We will keep this issue open, so that it is visible for people who try to use the IOSvc with the wrapper.

If necessary we will come back to this in the future to add support. For now we will mainly try to avoid the segmentation fault and rather give users a proper error for that.

[BrieucF]

Trying to raise the priority of this issue: it is not really a matter of running in multi-threaded way, it is rather that we try to write all the new algorithms with Functionals and this issue currently prevents one to access the ILCSoft world.

[samf25]

I would also like to add in my voice, here. The fact that we can't use the converters with Transformers is hampering my progress on Muon Collider work. I've converted a number of Marlin Processors to Transformers but now I have to run the converted algorithms separately from the ones that are still in MarlinWrappers.

[BrieucF]

Hi @samf25 , are these translated Marlin Processors available centrally in Key4hep?

[samf25]

No. Currently, they are just located in a separate repo (there's also TrackPerf, and I am currently working on some digitization libraries). Once I can get it all hooked up and running (with MarlinWrappers around they as of yet untranslated ones) they will be added to the MuCol software stack. I don't think there are any plans to include them centrally since they are specific to the muon collider.