METHOD FOR MINIMIZING LOCK PROCESSING WHILE ENSURING CONSISTENCY AMONG PAGES COMMON TO LOCAL PROCESSOR CACHES AND A SHARED EXTERNAL STORE

A computer implemented method for minimizing the grant of pages locks and the number of outstanding locks while ensuring consistency of the copies of pages resident among a first, and a second data cache with the original pages in shared external storage. A first processor requesting a lock on a designated page is granted a lock over the group of pages including the designated page in the absence of a concurrent lock to the page or group held by another processor. Any changed page is copied through to external storage. Otherwise, a processor intending to alter a page causes a global lock manager to notify concurrent lock holders, invalidate copies of the page in their local caches, and obtain an exclusive lock to the requesting process for the duration of its operation on the page. After this the lock is demoted to share and the changed page also copied through to external storage.