RFR(S) 8240205: Avoid PackageEntry lookup when loading shared classes

[Lois Foltan]

On 4/3/2020 1:23 PM, Calvin Cheung wrote:
> Hi Lois,
>
> Thanks for your review!
>
> On 4/3/20 9:46 AM, Lois Foltan wrote:
>> On 4/2/2020 8:58 PM, Calvin Cheung wrote:
>>> RFE: https://bugs.openjdk.java.net/browse/JDK-8240205
>>> webrev: http://cr.openjdk.java.net/~ccheung/jdk15/8240205/webrev.00/
>>>
>>> During loading of a shared class from a CDS archive, the 
>>> PackageEntry is being looked up in several places within the same 
>>> call stack. This RFE is to do the PackageEntry lookup at one place 
>>> and then pass it along to the subsequently called functions which 
>>> need it.
>>>
>>> Perf improvement on loading approx. 2000 classes on linux:
>>>
>>> instr delta = -17930620 -0.6155%
>>> time delta = -6.311 ms -0.7516%
>>>
>>> Passed tiers1 - 4 testing.
>>>
>>> thanks,
>>>
>>> Calvin
>>>
>>>
>> Hi Calvin,
>>
>> This looks good & promising on the numbers!  I have a slight concern 
>> that you've introduced yet another "get package entry from name" sort 
>> of function in SystemDictionaryShared. classfile/modules.cpp already 
>> contains a static method get_package_entry_by_name() but it operates 
>> on a package name not a class name.  Please consider moving 
>> SystemDictionaryShared::get_package_entry_from_class_name into 
>> ClassLoader near ClassLoader::get_package_from_class_name(). That 
>> seems like a more consistent place to add it that various areas of 
>> the JVM can take advantage of.
>
> The SystemDictionaryShared::get_package_entry_from_class_name function 
> is currently being used only within the SharedDictionaryShared class. 
> That's why it was declared private and I think that's the right place 
> for it.
>
> There also another SystemDictionaryShared::get_package_entry() which 
> operates on a package name and is very similar to the one in 
> ClassLoader. I can file another RFE to consolidate those 2 functions.

That would be great. Thanks!
Lois

>
> thanks,
>
> Calvin
>
>>
>> Thanks,
>> Lois