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Oracle® Containers for J2EE Orion CMP Developer's Guide 10g Release 3 (10.1.3) B19177-01 |
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# Configuring Concurrency Modes

The concurrency modes determine when to block to manage resource contention, or when to execute in parallel. For more information, see "Entity Bean Concurrency Modes and Resource Contention".

To set the entity bean with container-managed persistence's concurrency mode, add the appropriate concurrency value of `pessimistic`, `optimistic`, or `read-only` to the `locking-mode` attribute of the `<entity-deployment>` element (see Table A-1, "Attributes of the <entity-deployment> Element") in the OC4J-specific deployment descriptor (`orion-ejb-jar.xml` file). The default concurrency mode is `optimistic`. To change the concurrency mode to `pessimistic`, perform the following modifications:

    <entity-deployment ...  locking-mode="pessimistic"
     ...
    </entity-deployment>

The concurrency modes are defined on a per-bean basis and the effects of locking apply on the transaction boundaries.

Parallel execution requires the correct setting of the pool size for wrapper and bean instances.

For more information, see the following:

- "Avoiding Database Resource Contention".

- "Combining Entity Bean Database Isolation Level and Concurrency Mode".