Bug #69362 Abandoned load-balanced connections cause memory leak
Submitted: 31 May 2013 8:20 Modified: 20 Mar 20:19
Reporter: Alexander Soklakov Email Updates:
Status: Can't repeat Impact on me:
None 
Category:Connector / J Severity:S2 (Serious)
Version:5.1.x OS:Any
Assigned to: CPU Architecture:Any

[31 May 2013 8:20] Alexander Soklakov 
Description:
Load-balanced/failover connections cause memory leak if were not closed explicitly.

AbandonedConnectionCleanupThread should take care about such connections, but the problem is that refQueue keeps references to underlying ConnectionImpls not to the top object (LoadBalancingConnectionProxy eg.). So when application lost reference to the top connection object this object remains in strong references from ConnectionImpls and at the same time keeps strong references to these objects.

How to repeat:
Make a loop with steps:
1) create l-b connection;
2) assign null to this connection reference

Suggested fix:
1) Pass l-b object to NonRegisteringDriver.trackConnection(Connection newConn) instead of ConnectionImpls
2) Keep reference from ConnectionImpl to proxy as WeakReference.
[20 Mar 20:19] Filipe Silva 
Unable to reproduce in MySQL Connector/J 9.7.0.