RFR 8038212: Method::is_valid_method() check has performance regression impact for stackwalking

[Coleen Phillimore]

Hi again,

I have moved the metaspace vm internal test to the end of execution, and 
also test if klasses are in metaspace, which works fine.  Thank you for 
the suggestion!  Here is a new webrev:

http://cr.openjdk.java.net/~coleenp/8038212_2/

Thanks,
Coleen

On 5/13/14, 9:51 AM, Coleen Phillimore wrote:
>
> Hi Mikael,
>
> On 5/13/14, 6:33 AM, Mikael Gerdin wrote:
>> Hi Coleen,
>>
>> On Monday 12 May 2014 20.19.15 Coleen Phillimore wrote:
>>> Summary: Only prune metaspace virtual spaces at safepoint so walking
>>> them is safe outside a safepoint.
>>>
>>> Walking class loader data graph for contains is really slow for
>>> applications like nashorn that has a lot of class loader data.
>>>
>>> Tested with nsk.quick.testlist, jtreg tests, and jck tests. Also ran
>>>
>>> open webrev at http://cr.openjdk.java.net/~coleenp/8038212/
>>> bug link https://bugs.openjdk.java.net/browse/JDK-8038212
>> Thanks for taking care of this fix.
>> I think the idea of deferring CLDG::purge to the next safepoint 
>> cleanup is
>> sound.
>
> Oh great!  I'm glad you agree.
>>
>> I like the removal of CLDG::contains since it makes more sense to ask
>> Metaspace straight up.
>>
>> I have a small question about the test you added:
>>
>> 3798   static void test_contains() {
>> 3799     // Test that all the methods in the CLDG are contained
>> 3800     ClassLoaderDataGraph::methods_do(assert_contains);
>> 3801   }
>>
>> Have we always allocated methods at this point in the VM startup?
>
> I thought this ExecuteVMInternalTests (or whatever the option is 
> called) is at shutdown?  I'll check.
>> Should we also test CLDG::classes_do to make sure it works for the 
>> compressed
>> class space?
>
> I had that same thought this morning.  Yes, I'll add it.
>
> Coleen
>
>>
>> /Mikael
>>
>>> Marcus L. tested it with nashorn tests.
>>>
>>> Thanks,
>>> Coleen
>