ClassLoader leak in 6.0.1 Final when building incrementally ----------------------------------------------------------- Key: DROOLS-521 URL: https://issues.jboss.org/browse/DROOLS-521 Project: Drools Issue Type: Bug Security Level: Public(Everyone can see) Affects Versions: 6.0.1.Final Reporter: Craig West Assignee: Mario Fusco Fix For: 6.1.0.Final I am currently converting a Drools 5.5.0 installation to 6.0.1 Final, due to many memory leaks in 5.5.0. Our use case involves a knowledgebase of several thousand rules which are updated at run-time quite frequently. As a result, we have found it necessary to do incremental builds of rules. I based the code for this on the integration tests: https://github.com/droolsjbpm/drools/blob/master/drools-compiler/src/test... This is working fairly well so far, but while testing, I noticed a fairly severe increase in PermGen heap usage every time I modify my rules. Using jhat and the Eclipse memory analyzer, I was able to track down the source of the problem to a classloader leak in the JavaDialect class. Whenever a rule is added to the JavaDialect, a RuleErrorHandler is added to an internal Map named errorHandlers. Unfortunately, this RuleErrorHandler is never removed, and it contains a reference to a stale PackageClassLoader. I have successfully fixed this by adding a call to this.errorHandlers.clear(); at the end of JavaDialect.compileAll(). As far as I have been able to determine, the errorHandlers map is no longer necessary at this point, and any further calls to compileAll should be preceded by updated addRule calls