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Summary

Jobs currently fall into two broad types: singletons, where only one instance of the job may be active at any one time; and instance jobs where any number may be active, and all start requests start a new instance. This specification proposes the addition of a third type, jobs where the number of instances is limited by giving each a unique name; only a new name will start a new instance.

Rationale

In practice, unlimited-instance jobs are quite rare and difficult to use since any number can be running at once thus contention of resources and locking become an issue. While the Resources specification attempts to resolve the locking issues, this would cause new instances to be queued after the active one instead of just re-using the active one.

Use cases

Scope

This scope of this specification is limited to the addition of an intermediate instance limitation between singleton and unlimited; no other issues are addressed.

Design

Implementation

Data preservation and migration

These changes are backwards compatible with the previous behaviour, since they only add new functionality.


NamedInstances (last edited 2011-08-26 04:10:16 by localhost)