The Process Manager in the ATLAS DAQ System

The Process Manager is the component responsible for launching and controlling processes in the ATLAS DAQ system. The tasks of the Process Manager can be coarsely grouped into three categories: process creation, control and monitoring. Process creation implies the creation of the actual process on behalf of different users and the preparation of all the resources and data needed to actually start the process. Process control includes mostly process termination and UNIX signal dispatching. Process monitoring implies both giving state information on request and initiating call-backs to notify clients that processes have changed states. This paper describes the design and implementation of the DAQ Process Manager for the ATLAS experiment. Since the Process Manager is at the basis of the DAQ control system it must be extremely robust and tolerate the failure of any other DAQ service. Particular emphasis will be given to the testing and quality assurance procedures carried out to validate this component.