October 2022 Meeting Notes

Offline Leads Meeting Notes 10/12/22

Attendees: Tom Junk, Wes Ketchum, Giuseppe Cerati, Tingjun Yang, Erica Snider, Katherine Lato

As planned, the majority of the meeting was to discuss the multithreading LArSoft Workshop. While it is summarized here for convenience, the latest information can be found in the Multithreading LArSoft Workshop Information document.

Multithreading LArSoft Workshop Information 

Timeframe: February 2023, Two possible dates proposed:

  1. Feb. 6th and 7th (Monday pm, Tuesday all day)  or 
  2. Feb. 16 and 17th (Thursday all day,  Friday morning)
  • Need to determine availability of relevant domain experts (MT + experiment)

Tentative agenda: 

  • Presentations – half day (see “Known topics to discuss” below)
  • Working groups (in parallel with expert help as needed) – half day (+ 2 hrs )
  • Lesson learned/Future plans – 2 hrs

Specific, candidate pieces of code or workflows for which we could use the workshop to implement and/or design multi-threaded or thread-safe solutions that experiments think would help to have in core LArSoft:

  • Services used that are needed to run workflows in MT mode. (Know issues with some services that access databases.) 
  • Detector response simulation code that is used in the new LArG4 framework
  • Photon visibility library calculation that uses GPU for single-photon tracking
  • Interfaces to the data source (eg, for code in a thread accessing an event segment)
  • 1D deconvolution (which some experiments still use for the time being) (DUNE not interested in new 1D workflows and would like to move away from existing ones)

It might also be helpful in planning for a workshop to have the experiments present on what they have done to effect thread-safety/multi-threading. We can arrange a corresponding presentation with a brief overview of multi-threading in art, and the components of LArSoft that are already thread-safe / thread-efficient, and which are works in progress. Would this be useful in advance of a workshop?

Known topics to discuss

  • Multi-threading in WireCell and LArSoft integration (Wes is talking to WC)
  • Multi-threading / thread safety in Pandora (Wes is reaching out to Pandora)
  • Photon visibility in ICARUS / SBN (?)  (Wes is talking to Diego)
  • ICARUS workflows
  • Status of thread-safety / multi-threading in LArSoft
    • Services
    • Hit finding
    • Geant4 / LArG4
  • DUNE event serialization / parallelization (See “Comments from David Adams regarding DUNE’s use cases” in the Multithreading LArSoft Workshop Information document)
  • Any other round-table experiment presentations

Please let us know if you have any comments or corrections.

Erica & Katherine