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.
|Consider for promotion||No|