Synchronization using commitment

Abstract

A method of sharing a file object among a plurality of competing processes, the file object having a content that at least one competing process may need to adjust so that the file is suitable for the operating environment of the competing process. To help make an adjustment, the file object includes a state attribute that indicates whether or not the file is committed and whether the file is in an inconsistent state. If the file contents are suitable for the specific process and the file object is not committed, the file can be committed by the specific process. If the file contents are not suitable for the specific process and the file object is not committed, the file is locked, set to inconsistent, adjusted, committed by the specific process and then unlocked. This process improves concurrency of the competing processes and reduces message overhead.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]Field of the Invention[0002]The present invention relates generally to a loosely-coupled multi-processor system that shares a commonly-used file, and it more particularly relates to processes that execute on each of the processors of the multi-processor system; the invention reduces the message traffic among the processors needed to achieve a single, consistent image of the commonly-used file.DESCRIPTION OF THE RELATED ART[0003]FIG. 1 shows a system setting in which the present invention operates. In this figure there are a plurality of processing systems 10, 12, 14, 16, 18, preferably having a similar architecture, connected via a number of point-to-point connections 20, 22, 24, 26, 28, 30. One or more of the processing systems (storage systems) 16, 18 provide storage-related functions for the other processing systems (client systems) 10, 12, 14 and these storage systems 16, 18 arc connected to one or more permanent storage devices 32, 3...

AI Technical Summary

Benefits of technology

[0012]One advantage of the present invention is that the message traffic is greatly reduced from two messages for each check of the shared file to either none or one message in the most common cases. One message is needed if the state value of the file object is ‘uncommitted’ and its contents are suitable for use. No message is needed is if the state value of the file object is ‘committed’ and the file content is suitable for shared use by the specific process. Only when the file must be adjusted are more messages required. However, that case occurs rarely.

[0013]Another advantage is that the client processes can each operate with a greater degree of concurrency because each of the client processes has access to the shared file without a lock being required in order to determine whether the file contents are suitable for use. In most cases the file is in the proper condition for that client process and needs no adjustment, which means that no locks are required and a process can continue its execution of the shared file without delay.

Problems solved by technology

If the state value of the file object is ‘committed’ and the file content is suitable for use by the specific process, the method shares the committed file; otherwise, the method returns a failure status.

However, that case occurs rarely.

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