Potential memory leak due to an increasing of (ROOT) fObjects in (ROOT) TProcessID

All those objects (src/objects) containing a data member with (ROOT) TRef containers (vectors, maps, ...) will increase indefinitely the internal fObject in TProcessID, and eventually consume all available memory (if small RAM computer or large files processing).

The problem can be easily spotted by performing a simple analysis with the ClusteringSpatial or the Tracking4D modules activated, and running a top command for instance (to see how it's increasing memory consumption).

This diagnostic has been extracted from https://root.cern.ch/doc/master/classTRef.html, where the potential solution is also presented there: just reset the number fObjects in the event loop.

(This behavior has been observed with ROOT v6.22 and v6.24, but probably it is independent of the ROOT version.)