28th Conference on Computing in High Energy and Nuclear Physics (CHEP 2026)

Evaluating the scalability of CERN’s HTCondor batch system towards the High-Luminosity LHC

26 May 2026, 13:45

18m

Chulalongkorn University

Oral Presentation Track 7 - Computing infrastructure and sustainability Track 7 - Computing infrastructure and sustainability

Speaker

Antonio Delgado Peris (CERN)

Description

The CERN Tier-0, representing around 25% of WLCG’s total CPU capacity, currently handles 125 thousand concurrent jobs. For HL-LHC at full luminosity, we expect this number to increase by a factor between 4 and 7. Therefore, CERN's HTCondor batch system will need to manage a much larger pool of resources and many more computing tasks. This will have an impact on HTCondor's central components, Collector and Negotiator, which need to gather information about available computing resources and idle tasks awaiting execution, in order to match and schedule them. This work analyzes the factors impacting the scalability of these central components, and discusses the results of our large-scale stress tests, performed in conditions similar to those expected during the High-Luminosity era. The lessons learnt from this testing will help us dimension CERN's batch system service to ensure readiness for the HL-LHC challenge.