International Business Machines Corporation

Peter M Wottreng

Arthur Douglas Smet

William S Davidson

Robert W Collins

James S Effle

Steven Michael Dickes

Scott D Hammersley

Carle J Larson

Russell J Weinschenk

A method and apparatus for the intraprocess locking of a shared resource in a computer system is disclosed. A computer system operates under the control of an operating system. The operating system supports the asynchronous execution of a plurality of tasks, referred to herein as processes. Each process is capable of being executed by a plurality of asynchronously executing programs. In addition to assuring that only one process may use a shared computer resource, such as a magnetic storage device, tape drive, printer, software module, message queue, etc, at one time, the operating system also grants access to a shared computer resource at the level of a program operating within a process. When one program executing within a process accesses a shared computer resource, it requests that the operating system lock out all other programs executing asynchronous within that process, as well as other processes executing within the computer system, from that shared resource. Different types of locks, such as exclusive and shared locks, are also supported.

Method and apparatus for intraprocess locking of a shared resource in a

A recovery mechanism restarts jobs following correction of a system failure and automatically marks the jobs for interruption at a logical boundary. The logical boundary is above logical file updating functions such that logical files are in a known state when jobs reach the boundary. When a system failure is detected which has not yet resulted in lost data, an image of working memory, including hardware status is saved on nonvolatile storage. After the failure has been resolved, the system is initially loaded with operating programs (IPL) and working memory is reloaded from the nonvolatile storage. All jobs which were reloaded are marked for interrupt at a machine instruction boundary, and processing is started. After all jobs have reached the boundary, or a predetermined time has elapsed, processing is stopped and the system is re-IPLed. There are few system index recoveries to be performed, since most jobs reached a point where logical files were synchronized with corresponding data.

Job interrupt at predetermined boundary for enhanced recovery

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Rochester, MN, United States of America

Peter M Wottreng