Evolution of the ALICE Software Framework for Run 3

Abstract

ALICE is one of the four major LHC experiments at CERN. When the accelerator enters the Run 3 data-taking period, starting in 2021, ALICE expects almost 100 times more Pb-Pb central collisions than now, resulting in a large increase of data throughput. In order to cope with this new challenge, the collaboration had to extensively rethink the whole data processing chain, with a tighter integration between Online and Offline computing worlds. Such a system, code-named ALICE O 2 , is being developed in collaboration with the FAIR experiments at GSI. It is based on the ALFA framework which provides a generalized implementation of the ALICE High Level Trigger approach, designed around distributed software entities coordinating and communicating via message passing. We will highlight our efforts to integrate ALFA within the ALICE O 2 environment. We analyze the challenges arising from the different running environments for production and development, and conclude on requirements for a flexible and modular software framework. In particular we will present the AL-ICE O 2 Data Processing Layer which deals with ALICE specific requirements in terms of Data Model. The main goal is to reduce the complexity of development of algorithms and managing a distributed system, and by that leading to a significant simplification for the large majority of the ALICE users. *

The ALICE O2data quality control system

“…The O 2 software is based on a multi-process message-based system with a zero copy approach in the main processing flow. A Data Processing Layer [5] software framework is being developed on top of the FairMQ data transport layer [6].…”

Data Analysis using ALICE Run 3 Framework

“…The implications for the software architecture and framework of the ALICE experiment upgrades [1] for the so called Run 3 of the Large Hadron Collider (LHC) have already been detailed elsewhere, in particular describing the new Online -Offline (O 2 [2]) architecture and its Data Processing Layer (DPL [3]). How those changes will reflect on the end-user analysis software and how it is run is hereby illustrated.…”

The ALICE Analysis Framework for LHC Run 3

“…The DPL is currently under very active development [10]. Under the hood, communication is handled through FairMQ [11], which in turn uses either ZeroMQ [12] or a shared memory backend.…”

“…Prototypes of the O 2 simulation [14] and reconstruction [10] workflows are using the DPL. We have based the analysis workflow prototype on it as well.…”