[CAMEL-6144] Optimistic Locking Required for JdbcAggregationRepository in order for Camel Aggregation to work in a Clustered environment

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.9.2
• Fix Version/s: 2.12.0
• Component/s: camel-sql

Environment

Camel Aggregation in more than one server each of them using JDBCAggregationRepository and using a common DB table to store aggregated exchanges.

• Estimated Complexity: Advanced
• Assignee: Claus Ibsen
• Reporter: Shivakumar
• Created: 08/Mar/13 00:02
• Updated: 20/Nov/14 12:10
• Resolved: 24/Jul/13 11:41

Description

Listing two problems here. And a solution that is needed to fix these problems.

1) A Race condition leading to below ConstraintViolationException when two Camel Aggregator's trying to insert into the AGGREGATION DB table for same correlationkey(ID).

"org.hibernate.exception.ConstraintViolationException: ORA-00001: unique constraint (USLDB_UAT2.AGGREGATION_PK) violated
at org.hibernate.exception.internal.SQLExceptionTypeDelegate.convert(SQLExceptionTypeDelegate.java:74)
at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:49)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:125)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:110)
at org.hibernate.engine.jdbc.internal.proxy.AbstractStatementProxyHandler.continueInvocation(AbstractStatementProxyHandler.java:129)
at org.hibernate.engine.jdbc.internal.proxy.AbstractProxyHandler.invoke(AbstractProxyHandler.java:81)
at $Proxy171.executeUpdate(Unknown Source)
at org.springframework.jdbc.core.support.AbstractLobCreatingPreparedStatementCallback.doInPreparedStatement(AbstractLobCreatingPreparedStatementCallback.java:73)
at org.springframework.jdbc.core.support.AbstractLobCreatingPreparedStatementCallback.doInPreparedStatement(AbstractLobCreatingPreparedStatementCallback.java:1)
at org.springframework.jdbc.core.JdbcTemplate.execute(JdbcTemplate.java:587)
at org.springframework.jdbc.core.JdbcTemplate.execute(JdbcTemplate.java:615)
at org.apache.camel.processor.aggregate.jdbc.JdbcAggregationRepository$1.doInTransaction(JdbcAggregationRepository.java:137)
at org.apache.camel.processor.aggregate.jdbc.JdbcAggregationRepository$1.doInTransaction(JdbcAggregationRepository.java:113)
at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:130)
at org.apache.camel.processor.aggregate.jdbc.JdbcAggregationRepository.add(JdbcAggregationRepository.java:113)
at org.apache.camel.processor.aggregate.AggregateProcessor.doAggregation(AggregateProcessor.java:260)
at org.apache.camel.processor.aggregate.AggregateProcessor.process(AggregateProcessor.java:197)
at org.apache.camel.util.AsyncProcessorConverterHelper$ProcessorToAsyncProcessorBridge.process(As..."

2) A similar Race condition happens when more than one Camel Aggregator(s) tries to update a row in the AGGREGATION table. This problem does not lead into any exceptions. But it leads into missing exchanges. Because both the Aggregator's are trying to update the same row in the AGGREGATION table, But one update is overwritten by other update, thus losing an exchange.

SOLUTION:
==========
Optimistic locking should be enabled / applied for JdbcAggregationRepository to handle this race condition.

Issue Links

• is related to: CAMEL-7810 Dropped exchanges when aggregating with JdbcAggregationRepository