RFR (M): JDK-8159262: Walking PackageEntry Export and ModuleEntry Reads Must Occur Only When Neccessary And Wait Until ClassLoader's Aliveness Determined

[Lois Foltan]

On 6/27/2016 12:03 PM, Zhengyu Gu wrote:
> Hi Lois,
>
> I have a question:
>
> classLoaderData.cpp # 1004 - 1013
>
> If there is no class loader unloaded, (for example, _unloading == 
> NULL), do you still need to execute this purge loop?
Hi Zhengyu,

Thank you for the review.  I have addressed your concern by moving the 
purge loop into the following conditional that only executes "if 
(seen_dead_loader)", nice catch.  This updated webrev also contains an 
improvement to the test ModuleStress.java to include a module defined to 
a custom system class loader, specified via -Djava.system.class.loader.

http://cr.openjdk.java.net/~lfoltan/bug_jdk8159262.2/webrev/

Thanks,
Lois

>
> Thanks,
>
> -Zhengyu
>
> On 06/22/2016 10:51 AM, Lois Foltan wrote:
>>
>> On 6/22/2016 8:56 AM, Alan Bateman wrote:
>>>
>>>
>>> On 22/06/2016 13:51, David Holmes wrote:
>>>>
>>>> How do you envisage any system classloader "dying" ??
>>> The system class loader (be it the built-in application class loader 
>>> or a custom system class loader configured via 
>>> -Djava.system.class.loader) will/can never be GC'ed. 
>>> ClassLoader.getSystemClassLoader() always returns a reference to it 
>>> (for example).
>> Ahh, ok, I was being overly cautious, so no opportunity to reset the 
>> system class loader dynamically at all? 
>> SystemDictionary::_java_class_loader is not initialized until after 
>> the module system initialization is complete.  Due to this I have 
>> updated my webrev to check for either the built-in application class 
>> loader or a custom system class loader and have renamed the method to 
>> is_system_class_loader().
>>
>> http://cr.openjdk.java.net/~lfoltan/bug_jdk8159262.1/webrev/
>>
>> Thanks,
>> Lois
>>
>