CachedIntrospectionResults cannot be cleared for null class loaders [SPR-9189]

[spring-projects-issues]

Paul Austin opened SPR-9189 and commented

If a class loaded by the system class loader (null) then it is cached by the CachedIntrospectionResults class. However there is no way to clear this item from the cache as clearClassLoader ignores null class loader arguments.

This means that the classCache will include a reference to the CachedIntrospectionResults thus preventing in some cases CachedIntrospectionResults from being garbage collected.

The class that causes this problem in my spring + spring security app is ArrayList. It seems to happen when I include a task scheduler in my application.

I tried to create a simple test case below. But it was able to unload the classes in this case.

public class TestListener implements ServletContextListener {

public void contextInitialized(ServletContextEvent sce) {
CachedIntrospectionResults.acceptClassLoader(Thread.currentThread()
.getContextClassLoader());
BeanUtils.getPropertyDescriptors(ArrayList.class);

}

public void contextDestroyed(ServletContextEvent sce) {
CachedIntrospectionResults.clearClassLoader(Thread.currentThread()
.getContextClassLoader());
}
}

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Affects: 3.0.7

Backported to: 3.1.4

[spring-projects-issues]

Paul Austin commented

Any updates on this issue?

[spring-projects-issues]

Chris Beams commented

Hi Paul,

Please do what you can to put together a simple project that reproduces this issue. We would have to do the same in order to address it. You can follow the instructions here, thanks!

[spring-projects-issues]

Juergen Hoeller commented

As of 3.2.1 and 3.1.4, clearClassLoader(null) will remove cached classes that have been loaded by the system class loader, as expected.

Juergen