ROOT Team Meeting

Monday 12 Jun 2023, 16:00 → 17:35 Europe/Zurich

32/1-A24 (CERN)

Axel Naumann (CERN), Lorenzo Moneta (CERN)

Zoom link in announcement email; please contact rootdev@cern.ch if you did not receive it!

## Any news?

* Jonas H. was in Barcelona where he talked to a comple of people who want to try out clang-repl
* ROOT might soon compile on Free-BSD again

* Question by Vincenzo: what about the next 6.28 Patch release?
 * A missing module needs to be added for CMS
 * ATLAS also has raised some issues already that should be fixed in a next patch release

## Shift handover

Jonas to Bertrand

##

## Meeting summary

### TMVA

 * There was no meeting

### RooFit
 * Dicussion on JSON format

### Godparents/planning meeting

 * Waiting for Fermilab to make progress on the ROOT collaboration

 * LHCb uses some library that collides with things in namespace `std`, so the
   goal is to avoid using namespace `std` in Cling for 6.30 (backporting it would
   be a too massive change).

### I/O meeting

 * Discussing about one week workshop with RNTuple developers on designing and
 coding,

 * 6th of november: RNtuple workshop with the experiments.

 * Discussion on `std::set` support in RNTuple.

 * Late schema extension is merged now, pepole in ATLAS (Martin/Marten?) are trying it out.

## GitHub issues

## Summer student course

 * They booked the only

 We need at least three poeple for each slot:

 1. Lorenzo, Axel, Florine
 2. Axel, Jonas H., Vinzenzo
 3. Jakob, Jonas R., Florine, Vincenzo

 Axel will send around the correct names later so these people can get self-organized.

## Discussion about C++17

* Presentation by Vincenzo

* Axel: what could be concerns with upgrading the minimum standard to C++17?
 * Maybe the experiments don't like it?

* Axel: we might run into problems with libraries on distros that are built only with C++14.
* Axel: Some packages that depend on ROOT might not support C++17

* Jonas H.: since the distros that don't support C++17 are by now end of life, I don't see any problem

* Jonas H.: the right standard need to be set at configuration time

* Fermilab should be fine with it, Axel still wants to reach out to the small experiments at CERN as well.

* We should put a warning/error in the ROOT headers if people try to compile their own code with an incompatible C++ standards

* Serguei: note that GSI still uses Debian 10

So it's decided, the minimum standard will be C++17 and Vincenzo will do the PR!

## Old JIRA issues

## Roundtable

### Guilherme

 * xrootd release next year will require C++17 as well

### Serguei

 * Fixing several bugs in jsROOT

### Philippe

 * Working on bug reports

### Jonas H.

 * Last week in Barcelona

### Bertrand

 * Several issues on the forum took some time

### Lorenzo

 * Mostly in LHCC
 * Reviewing some PR by Jonas and GSoC student
 * Discussing with Omar to put scipy optimizer inerface into ROOT

### Jolly

 * Move to openSYCL
 * Migrating the environment to that is still some work

### Victoria

 * Becoming familiar with the repository
 * Implementing bit flips
 * Have to discuss with Javier and Jakob what the next step is

### Olivier

 * Lots of work on the forum
 * implemented `rootbrows --web=off`
 * several doc and graphics fixes, like zooming with the scroll wheel inside a histogram with 16k bins

### Jonas R.

 * Fixed some bugs in RooFit BatchMode
 * Worked on H->gg analysis tutorial with ROOT.
   * Where should "integrated tutorials" go that showcase e.g. RDF + RooFit?
 * Fixed some compiler warnings in the nightlies
   * What about non-declared template specializations in headers?
   * could be solved with `extern template`

### Florine

 * Has worked on `std::set` implementation in RNTuple
 * Revisiting CHEP benchmarks and adding more things for Jakob to show on the ATLAS meeting

### Jakob

 * Implemented zigzag encoding for integers, which gives tome improvement at the percent level

### Vinzenco

 * Code review and discussion about RDataFrame stuff
 * Found a bug in RDataFrame snapshot, addressing all these issues, writing tests

### Javier

 * Patches for RNtuple
 * Tweaks in the CI
 * Code review
 * This week: work on RNtuple
 * On vacation on the next couple of days

### Axel

 * Inlining `TRandom3`, accelleration proposal by ChatGPT
 * SFT is trying to get money together with CMS and ATLAS from a private donation
 * PhD from national funding agency (DFG, germany) for RooFit (LHCb student who would be physically at CERN with the ROOT team for 2 years)
 * Discussion with Intel: modern Xeon processors have compression baked into hardware, if they provide students via openlab/IT that's nice
 * On vacation all of July

16:00 → 16:01 Find notetaker

16:01 → 16:05 News

16:05 → 16:10 Shift handover

16:10 → 16:20 Meeting Summaries and Plans

• I/O
• TMVA
• RooFit
• Planning / Godparents /...
• LIM

16:20 → 16:40 Issues

Review of last week's open items

16:40 → 17:00 Topics

• Summer student courses:
• the morning of the 21st of June (at the IT Amphitheatre)
• afternoon of 28th of June (at the IT Amphitheatre)

• afternoon of 27th of July (at 13/2-005)

• Bumping minimal C++ std to 17 [Vincenzo]

ROOT_transition_cpp17.pdf

17:00 → 17:25 Round Table

17:25 → 17:30 A.O.B.