[jboss-jira] [JBoss JIRA] (JBCL-185) BaseClassLoader.loadClass() is slow under load

BaseClassLoader.loadClass() is slow under load ---------------------------------------------- Key: JBCL-185 URL: https://issues.jboss.org/browse/JBCL-185 Project: JBoss ClassLoader Issue Type: Enhancement Components: ClassLoader Affects Versions: JBossCL.2.0.9.GA , JBossCL.2.0.11.GA Environment: -JBoss Enterprise Application Platform (EAP) 5.1.2 -JBossCL 2.0.9.GA Reporter: Aaron Ogburn Assignee: Ales Justin Fix For: JBossCL.2.0.12.GA Attachments: BaseClassLoader.java, JBCL-185.patch, JBCl-185testcase.tar.gz Classloader performance dropped from EAP 4.3 to 5. Thread dumps show threads facing contention in the classloader: java.lang.Thread.State: BLOCKED (on object monitor) at org.jboss.classloader.spi.base.BaseClassLoader.doLoadClass(BaseClassLoader.java:495) - waiting to lock <0x80e22960> (a org.jboss.classloader.spi.base.BaseClassLoader) at org.jboss.classloader.spi.base.BaseClassLoader.loadClass(BaseClassLoader.java:447) at java.lang.ClassLoader.loadClass(ClassLoader.java:247) at org.jboss.classloading.spi.DelegatingClassLoader.loadClass(DelegatingClassLoader.java:87) at java.lang.ClassLoader.loadClass(ClassLoader.java:247) at org.jboss.util.loading.DelegatingClassLoader.loadClass(DelegatingClassLoader.java:97) at java.lang.ClassLoader.loadClass(ClassLoader.java:247) These are repeat lookups. The thread and classloader trace logging show that these look ups are not returning cached values from checkCacheAndBlackList() and so they are having to go progress through doLoadClass() and the baseclassloderdomain to finally return the class from another classloaders cache. This is bad as threads are forced to synchronize to return a cached class from elsewhere whereas the cached value return could all happen concurrently.