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Management of a Queue for a Serialized Resource

IP.com Disclosure Number: IPCOM000124022D
Original Publication Date: 1996-Dec-01
Included in the Prior Art Database: 2005-Apr-06
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Fulkerson, CE: AUTHOR [+4]

Abstract

Disclosed is an enhancement to a lock management method for distributed computer systems with shared resources (e.g., instances of the MVS/ESA operating system connected with IBM's Coupling Facility). While the detail of the lock-management and queue-management capabilities of the coupling facility have been covered extensively elsewhere, this article focuses on the design of the management of the list of pending requests (deferred due to lock contention).

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This is the abbreviated version, containing approximately 82% of the total text.

Management of a Queue for a Serialized Resource

      Disclosed is an enhancement to a lock management method for
distributed computer systems with shared resources (e.g., instances
of the MVS/ESA operating system connected with IBM's Coupling
Facility).  While the detail of the lock-management and
queue-management capabilities of the coupling facility have been
covered extensively elsewhere, this article focuses on the design of
the management of the  list of pending requests (deferred due to lock
contention).

      In this design, the list is maintained not in the coupling
facility but locally in the memory of the system which at present
owns the lock (more precisely, owns the process or user which owns
the lock).  When contention for the lock occurs, this system
maintains the  queue of pending requests.

      When the lock is released, normal lock processing will grant
control of the lock to the next pending request.  In this design,
though, if the user, or process, which is next to be granted control
of the lock is running in a different system than the process which
just released the lock, the queue of additional pending requests is
transferred from the system where it was maintained to the system
where the process which will now own the lock, is running.

      This transfer occurs either by using messages or by relying on
shared data in the coupling facility.  However, once the transfer is
complete, the management of the pending requests will...