[jboss-jira] [JBoss JIRA] (DROOLS-890) Thread deadlock issue in class ProjectClassLoader.java

[Thomas Leung (JIRA)]

    [ https://issues.jboss.org/browse/DROOLS-890?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13105422#comment-13105422 ] 

Thomas Leung commented on DROOLS-890:
-------------------------------------

We did build from Drools source on 6.2.0.Final with the change following your provided link https://github.com/droolsjbpm/drools/commit/183518527.
Basically it mainly synchronize the method public synchronized Class<?> defineClass(String name, String resourceName, byte[] bytecode).

However, the same deadlock issue still happened while we run a load test again.

This deadlock happened always when we run load test during the past couple of weeks. We noticed that everytime it locked at the below line in ProjectClassLoader.java:

        protected Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException {
            try {
                return loadType(name, resolve);
            } catch (ClassNotFoundException cnfe) {
                synchronized(projectClassLoader) {
                    try {
                        return projectClassLoader.internalLoadClass(name, resolve);            <== wait for lock projectClassLoader object
                    } catch (ClassNotFoundException cnfe2) {
                        return projectClassLoader.tryDefineType(name, cnfe);
                    }
                }
            }
        }

That means it throws ClassNotFoundException in loadType(name, resolve). Is it an expected exception in normal usage or it happened abnormally?

> Thread deadlock issue in class ProjectClassLoader.java 
> -------------------------------------------------------
>
>                 Key: DROOLS-890
>                 URL: https://issues.jboss.org/browse/DROOLS-890
>             Project: Drools
>          Issue Type: Bug
>          Components: core engine
>    Affects Versions: 6.1.0.Final
>            Reporter: Vivek Hingorani
>            Assignee: Mario Fusco
>             Fix For: 6.3.0.Final
>
>
> In our project , we are using drools6.1.0.Final jars and the rules are deployed in a jar. Another application when trying to use the rules jar is getting thread deadlock problem. Stack trace is 
> at org.drools.core.common.ProjectClassLoader$InternalTypesClassLoader.loadClass(ProjectClassLoader,java284)
> Two threads are in deadlock condition on this thread. I restarted the application and the error is gone but we need to fix this issue so that it is not reproduced later.The class is in drools-core jar



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