RFR: 8222422: vmTestbase/nsk/jdi/ClassLoaderReference/definedClasses tests failed with Unexpected Exception: null

[David Holmes]

Hi Daniil,

On 11/05/2019 12:10 pm, Daniil Titov wrote:
> Please review the change that fixes an intermittent failure of the test.
> 
> The tests checks the implementation of  the com.sun.tools.jdi.ClassLoaderReference class. The problem here is that while com.sun.tools.jdi.ClassLoaderReferenceImpl.definedClasses() iterates over all loaded classes to retrieve a classloader and compares it to the current one, some of the classes might become unloaded and garbage collected (e.g. org.graalvm.compiler.nodes.InliningLog$$Lambda$41.899832640 or jdk.internal.reflect.GeneratedConstructorAccessor1, etc.). If this happens then the attempt to retrieve a classloader for the collected class results in com.sun.jdi.ObjectCollectedException being thrown.

That seems odd to me. If you have a reference to the Class then it can't 
be unloaded. I would not expect allClasses() to have weak-references, so 
a class should not be unloadable while you are examining it. Unless it 
is finding VM anonymous classes (which it should not!).

David
-----

> The fix catches this com.sun.jdi.ObjectCollectedException and continues iterating over the rest of the classes.
> 
> Webrev: http://cr.openjdk.java.net/~dtitov/8222422/webrev.01
> Bug: https://bugs.openjdk.java.net/browse/JDK-8222422
> 
> Thanks!
> --Daniil
> 
>