ROOT Team Meeting

Name: ROOT Team Meeting
Start: 2025-09-08T16:00:00+02:00
End: 2025-09-08T17:30:00+02:00
Location: CERN

Monday Sep 8, 2025, 4:00 PM → 5:30 PM Europe/Zurich

13/3-005 (CERN)

Danilo Piparo (CERN), Jakob Blomer (CERN)

63815034196

Danilo Piparo

Philippe Canal

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Number of issues going down, but we still have quite a few things left to address.
POW Jamboree - No issues (Sept 22 and 24)

Fix for a Windows issue by adding a dependency (PR opened by Lukas). This is related to file opening and closing on Windows, potentially caused by the same macro being opened by two tests simultaneously.

### Meetings

LIM:
- Question regarding architecture—do we build with v2 or v3 for AVX? - we use defaults.
- Marco: 5% speedup using v3.
I/O meeting
Question raised about AOS/SOA I/O support. We need additional work here (an extra item in POW to address this starting this year).
Axel posted a paper by Jefferson Lab claiming that their method is 10x faster than TTree and RNTuple. However, the benchmark is based on reading from a large file (hot cache, not sure about the I/O involved). If TTree and RNTuple are used correctly, this claim may not be valid.
- Takeaway: The benchmarks were hand-coded and would have benefited from RDF bulk processing if they had been written in RDF.
Created a draft PR for a new TFile and DrawFile backend that uses curl instead of Davix, initially as an opt-in.

CMS: Monthly meeting with CMS.
CMS Crosspog: Focus on nanoAOD and derivatives, mostly in-development discussion.
Dune:
Meeting tomorrow at 5PM with two people from the US attending the ROOT workshop.

Bertrand
Conda build - builtins are disabled on windows to get it working.
Philippe
Issues with threads and threadLocal, recalling what was done 7 years ago. This issue only occurs with slow disks.
Serguey:
Work on the HTTP server (user space).
Issues/questions posted on the ROOT forum.
Vassil:
New approach to thread safety in cppInterop by Vipul.

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