[IBATIS-540] Classloader memory leak because of ThreadLocal in ResultObjectFactoryUtil

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.3.3, 2.3.4
• Fix Version/s: 2.3.5
• Component/s: Core
• Assignee: Jeff G. Butler
• Reporter: Sylvain Laurent
• Created: 03/Oct/08 08:16
• Updated: 28/Mar/09 21:28
• Resolved: 03/Oct/08 16:20

Description

I'm using iBatis in a webapp with Spring and facing memory leaks upon redeployment oft he webapp.
I tracked the leaks to ibatis, where the class ResultObjectFactoryUtil has a static ThreadLocal factorySettings

The problem is that the value bound to a Thread through this ThreadLocal is never nullified, and since the "factorySettings" is a static variable, the ThreadLocal instance is reachable as long as the ClassLoader of the webapp is reachable. But since the FactorySettings instance is bound to the Thread through a strong reference (see the JDK implementation of ThreadLocal in ThreadLocalMap$Entry), the classloader is finally never collected...

The solution is to always cleanup the ThreadLocal after usage (in SqlExecurtor)
I attach a patch for iBatis 2.3.4 to this issue

Issue Links

• is related to: IBATIS-376 Hot deploy issue