Nov 4 – 8, 2019
Adelaide Convention Centre
Australia/Adelaide timezone

ATLAS Event Store and I/O developments in support for Production and Analysis in Run 3

Nov 7, 2019, 3:30 PM
Hall F (Adelaide Convention Centre)

Hall F

Adelaide Convention Centre

Poster Track 2 – Offline Computing Posters


Marcin Nowak (Brookhaven National Laboratory (US))


During the long shutdown, ATLAS is preparing several fundamental changes to its offline event processing framework and analysis model. These include moving to multi-threaded reconstruction and simulation and reducing data duplication during derivation analysis by producing a combined mini-xAOD stream. These changes will allow ATLAS to take advantage of the higher luminosity at Run 3 without overstraining processing and storage capabilities. They also require significant changes to the underlying event store and the I/O framework to support them. These changes and their effects are discussed in the presentation:

  • The Run 2 I/O framework was overhauled to be thread-safe and
    minimize serial bottlenecks.
  • For object navigation, new immutable references are deployed, which
    don’t rely on storage container entry number so data can be merged
  • Filter decisions can be used to annotate combined output stream
    allowing for fast event selection on input.
  • Compression algorithms and settings were optimized to allow efficient
    reading of event selections.
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Primary authors

Peter Van Gemmeren (Argonne National Laboratory (US)) Jack Cranshaw (Argonne National Laboratory (US)) Marcin Nowak (Brookhaven National Laboratory (US))

Presentation materials