[jboss-jira] [JBoss JIRA] (WFLY-12098) Thread context class loader is wrong for ScheduledExecutorService threads

[Paul Pogonyshev (Jira)]

    [ https://issues.jboss.org/browse/WFLY-12098?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13783989#comment-13783989 ] 

Paul Pogonyshev commented on WFLY-12098:
----------------------------------------

Unfortunately, it's not trivial, as it is deeply embedded in our huge application and further complicated by the fact that the application can run both inside a Web container (WildFly) and outside it, with limited functionality. In pseudocode I could formulate it like this:

@WebListener
<whatever>
{
    public void contextInitialized (ServletContextEvent event)
    {
        use (jndiLookup ("java:comp/DefaultManagedScheduledExecutorService"));
    }
}

I'm not 100% sure, but it seems when the listener is informed that context is initialized, not _everything_ is actually initialized yet. In particular, when it tries to use the JNDI-provided ScheduledExecutorService, the service still uses class loader that cannot look up application's classes.

At some point later java:comp/DefaultManagedScheduledExecutorService is always replaced with one that uses correct class loader. However, I'm not sure when exactly this happens.

> Thread context class loader is wrong for ScheduledExecutorService threads
> -------------------------------------------------------------------------
>
>                 Key: WFLY-12098
>                 URL: https://issues.jboss.org/browse/WFLY-12098
>             Project: WildFly
>          Issue Type: Bug
>          Components: Concurrency Utilities
>    Affects Versions: 16.0.0.Final
>            Reporter: Paul Pogonyshev
>            Assignee: Ivo Studensky
>            Priority: Major
>
> Tasks submitted to the standard ScheduledExecutorService (JNDI: java:comp/DefaultManagedScheduledExecutorService) are executed in threads with class loader that cannot find application classes. This is a regression in 16.0 compared to 14.0 (haven't tested 15). Tasks submitted to the simple ExecutorService (JNDI: java:comp/DefaultManagedExecutorService) see the correct class loader.
> I.e. if I submit something like
>     () -> { System.out.println (Thread.currentThread ().getContextClassLoader (); }
> to both services (i.e. exactly the same task), I get the following output. For ScheduledExecutorService (wrong):
>     ModuleClassLoader for Module "org.jboss.as.ee" version 16.0.0.Final from local module loader @275710fc (finder: local module finder @525f1e4e (roots: [...]/wildfly/modules,[...]/wildfly/modules/system/layers/base))
> For ExecutorService (as expected):
>     ModuleClassLoader for Module "deployment.[...].war" from Service Module Loader
> Plain ExecutorService sees exactly the same class loader as normal threads in which HTTP request are processed. In version 14.0 this was also true for ScheduledExecutorService.



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