Code and Design Feedback request: 7114376: tune system dictionary size

[Dean Long]

OK :-)

dl

On 1/24/2012 6:42 PM, Karen Kinnear wrote:
> Dean,
>
> That is actually a really good idea. True, it is out of scope for the current release timeframe, but once we have the permgen removal
> changes in, we will want to move more metadata to per classloader data structures that will more quickly free up when we unload classes/classloader.
>
> I filed RFE to capture this idea - 7133093 and put my name on it because it sounds quite promising :-)
>
> thanks!
> Karen
>
> On Jan 23, 2012, at 6:22 PM, Dean Long wrote:
>
>> It is probably out of the scope of this CR, but is it possible that the internal data structure might one day change from monolithic hash table to something more hierarchical?  For example having a separate data structure per package or per classloader.  I was reading online about something called a HAT-trie that deals with shared prefixes and was designed with cache locality in mind.
>>
>> dl
>>
>> On 1/21/2012 11:04 AM, Karen Kinnear wrote:
>>> David,
>>>
>>> Thank you for asking, my mistake. Here is an accessible webrev.
>>>
>>> Webrev: http://cr.openjdk.java.net/~acorn/7114376/webrev/
>>>
>>> An alternative possibility for supplying a single flag might be: -XX:LoadedClasses=#
>>>
>>> This could be an anticipated count of expected total classes, which we could use
>>> internally to set the initial SystemDictionary size. This might outlast any internal changes
>>> in data structures.
>>>
>>> Tests run:
>>> vmsqe: nsk.quick.testlist: solaris-sparc, fastdbg - this includes sa testing
>>> jck: vm,lang,api: solaris-sparc, fastdbg
>>> JPRT - this includes CDS testing
>>> performance runs in progress, including frequency of checking need to resize
>>>
>>> thanks,
>>> Karen
>>>
>>> On Jan 21, 2012, at 12:04 PM, David Schlosnagle wrote:
>>>
>>>> On Fri, Jan 20, 2012 at 6:06 PM, Karen Kinnear<karen.kinnear at oracle.com>   wrote:
>>>>> Please review initial proposal for: 7114376: tune system dictionary size
>>>>>
>>>>> http://oklahoma.us.oracle.com/~kmkinnea/webrev/sdresize/webrev/
>>>> Karen,
>>>>
>>>> Is there a URL where this webrev is accessible outside of Oracle?
>>>>
>>>> Thanks,
>>>> Dave