DefaultDatabaseLocker causes Oracle to throw an exception "maximum open cursors
exceeded" under heavy load
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Key: AMQ-1702
URL: https://issues.apache.org/activemq/browse/AMQ-1702
Project: ActiveMQ
Issue Type: Bug
Components: Message Store
Affects Versions: 5.0.0
Reporter: Rob Davies
Assignee: Rob Davies
Fix For: 5.1.0
The API document for the java.sql.Statement class
(http://java.sun.com/j2se/1.4.2/docs/api/java/sql/Statement.html#close()) says
that statement objects are automatically closed during garbage collection,
however, under heavy load (i.e. for an application that is processing multiple
messages per second) you will quickly run out of cursors even before garbage
collection gets to reclaiming prepared statements. Also any application that
deals with huge volume is going to use a connection pool that also pools the
statements, which means that the statement you created are referenced by the
pool, thus they won't be garbage collected and closed. Just like the
connection.close triggers the connection to be marked as available in the pool,
statement.close will trigger the statement to be available in the pool for
whoever needs a statement for this connection.
As a result of running out of statements, DefaultDatabaseLocker causes Oracle
to throw an exception "maximum open cursors exceeded". And the broker looses
the DB lock and shuts down.
One solution would be to add a finally block onto the
DefaultDatabaseLocker.keepAlive() method to close statement explicitly.
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