METHOD AND MEANS FOR THE RETENTION OF LOCKS ACROSS SYSTEM, SUBSYSTEM, AND COMMUNICATION FAILURES IN A MULTIPROCESSING, MULTIPROGRAMMING, SHARED DATA ENVIRONMENT

Method and means for operating a computing system for controlling access to and maintaining the integrity of data resources shared by multiple applications executing on a plurality of central electronic complexes (CEC's) while minimizing communication of sharing control parameters between different electronic complexes. Each complex includes a resource lock manager (IRLM) which maintains the hold and wait locks for applications executing under one or more information management subsystems on the complex and selected wait locks for the other complex. Selective communication of lock request information is controlled by hash tables maintained in synchronization in each IRLM, which denote the interest of each complex in each hash class, or congruence class, of data resources. A first complex already having exclusive use of a congruence class grants locks on data resources which map into the congruence class without communication of the request to the other complex. When such communication is required, and the other complex determines that an inconsistent hold lock already exists for the data resource of the request, the lock request is waited in both IRLM's. When the inconsistant hold lock is subsequently released, the wait lock is deleted from the IRLM of the other complex, and the first complex grants the requested lock. Each IRLM also includes an identified subsystem list (ISL), which is maintained in synchronization and used along with the hash tables and hold/wait locks to retain locks across CEC, subsystem, and communication link failures and to enhance recovery thereafter.