Attendees: Guilherme, Danilo, Philippe, Chris J, Dan R., Zhe, Liz, Peter, Pere, JIm.

Action Items:

* Dan send his CMSSW filer merging module to root-dev

* Guilherme implements a callback triggers whenever a TMemFile is done being merged into output file.

* ROOT Team work on reducing cost of writing/compressing meta data to output file and also the cost of write/compress/uncompress/read of the meta data in the TMemFile.

Some notes

Danilo: we are in contact with Giovani (CMS) and Atilla (ATLAS) to discuss the use TDataFrame.

Philippe: How do we insure that ROOT’s implicit parallelism (GetEntry, Compression, Fitting) plays ‘nice’ with the framework.

Chris: If any CPU using task is scheduled through TBB then we share the same limited pool of thread and consequently there is not problem.

Danilo/Chris/Liz:  Should it make sense to restart the Concurrency Forums?  In what shape/form/frequency?

Liz: We definitively should … probably in connection to the HEP Community White Paper.

Danilo: ROOT Adopted TBB but we have an isolation layer and could ‘easily’ switch away from TBB if/when needed.

Liz: TBB came from Intel and until Intel stops supporting it and/or there is hardware that is both useful to us but does not interest Intel, we will be fine.  But indeed we should continue to look around at new things.

Philippe; New ROOT I/O Workshop on October 11th.