[CAMEL-11223] camel-jpa doesn't handle exclusive locks for concurrent consumers when setting consumeDelete to false

• Type: Improvement
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: 2.18.3
• Component/s: camel-jpa

Environment

Java JDK 1.8.0_121
Spring 4 (reproduced with Spring Boot 1.5.3)
RedHat RHEL 7.1 x86_64
Oracle 11G

• Estimated Complexity: Unknown
• Assignee: Unassigned
• Reporter: TEIKITEETINI-VAYSSE Loic
• Created: 02/May/17 09:52
• Updated: 01/Feb/18 15:00

Description

Deploying 4 instances of the same app containing a camel-jpa consumer polling on the same database, I noticed that several servers can consume the same entities.

The polling is currently done as follow :

1. Poll without lock on the `maxResult` first rows
2. On each row :
   1. Apply a lock select ... for update (NOWAIT)
   2. Consume entity
   3. Release the lock (commit)
   4. New Transaction
   5. Process exchange
   6. End Transaction

What can happen with several instances of the consuming on the same database is :

1. Server 1 polls the 10 first rows
2. Server 2 polls the same 10 first rows
3. Server 1 locks row 1 for update and consume it
4. Server 2 locks row 1 for update as the previous lock is already released and consumes it

This demand is related to my previous post on the user forum : http://camel.465427.n5.nabble.com/JPA-consumer-component-is-not-handling-multiple-server-concurrent-polling-td5797937.html