DD4hep Meeting June 18th, 2026

Present:     Andre, Juan, Markus, Peter

Apologies: Thomas

Link to minutes of previous meeting

Merged PRs

• PR1632:   feat: add DD4HEP_GENERATE_ROOTMAP_EXTRA_ENV hook to dd4hep_generate_rootmap (Wouter)

• PR1638:   Include type unsigned long long for macOS in GrammarTypes (Maxwell Cui)
  ISSUE1637: Missing registration of unsigned long long for macOSbug (Maxwell Cui)

• PR1639:   Bump actions/checkout from 6.0.2 to 6.0.3 dependencies github_actions (guthub-bot) 
• PR1642:   Update DDCAD collada duck example reference (Markus)
            ---> Adjust for new version of assimp
• PR1645:   DDG4: fix uncaught OSError raised by getpass.getuser() in Python 3.13 (Jason Patton)

Closed PRs, closed issues and fixed problems

• PR1587:   Fields/FieldTypes: performance related cleanups (David Lange)
                        ---> Stale PR

• ISSUE1535: How to add new output variables in Hitsquestion (matclim -> DD4SHip)
                        ---> Stale issue
                        ---> Unclear what was their final decision
• ISSUE1644: generating doxygen page locally (G.Grenier (CMS/ILD/Calice))
                        ---> Answered by Andre

Pending Problems

• ISSUE1297: Possible to dump all available readout elements?
                        ==> Possibly a copy of unsolved ISSUE580 from Valentin about enumerating all sensitive cells.
• ISSUE1335: Uniform random picking of points on detector surfaces for noise studies
                         This problem is linked to #1297 and #580.
• ISSUE1458: XML file vs TGeoStored geometry in GenFit
• ISSUE1501: Bug/Feature: Condense duplicated particle contributions in calorimeter question
• ISSUE1568: Sim hits between two sensitive volumes (Alexander Tuna)
• ISSUE1604: Question about random seed reproducibility when detector XML is modifiedquestion (Dr.Stubborn/Jiashen Luo)
• ISSUE1633: Decouple DD4hep Readers/Writers into Separate Source and Injection/Build Stagesenhancement (Simon Gardner)
• ISSUE1635: ddsim crashes when given a particle outside world volumebug (Andre)

Pending PR:

• PR1240:   Add multithreading support to ddsim (Wouter) 
• PR1590:   Fix more memory leaks (Juan)

• PR1606:   feat: AdePT physics list plugin for e+/e-/gamma offload to GPU [WIP] (Wouter)

• PR1617:   Make EventSeeder run before primary generation (Andre)
• PR1626:   feat: add support for python geometry plugins  (Wouter)
• PR1629:   Refactor Geant4Output2ROOT (Juan)
  
  

New:

• ISSUE1640: Print level for individual module (Shan Huang)
• ISSUE1643: Non-determinism in hit ordering when multiple detectors share readoutbug (Wouter)
• PR1636:       fix: honor G4OpticalParameters process activation flags in DDG4 (Wouter)
• PR1646:       Use Clang 22 instead of 19 in CI, soon unsupported (Juan)

Round Table

Andre:            NTR
Juan:              Ran multi-threading PR on larger scale. Speed-up was only very low. Needs investigation.
Markus:         NTR
Peter:             NTR
Thomas:        ------

Next meeting:   July 2nd, 2026