RFR(S) 8246181: Avoid walking SymbolTable during -Xshare:dump

[Yumin Qi]

Thanks again --- tested jtreg runtime/cds/appcds on fastdebug.


Yumin

On 6/24/20 10:16 AM, Calvin Cheung wrote:
>
>
> On 6/24/20 10:08 AM, Yumin Qi wrote:
>>
>> HI, Calvin
>>
>>
>> Thanks for review!
>>
>> On 6/24/20 9:18 AM, Calvin Cheung wrote:
>>> Hi Yumin,
>>>
>>> Code changes look good.
>>>
>>> I guess the following assert isn't applicable to the new code 
>>> anymore since the SymbolTable::do_add_if_needed will be called for 
>>> non-permanent symbols?
>>>
>>> 1244     assert((*sym)->is_permanent(), "archived symbols must be 
>>> permanent");
>>>
>>> Are we archiving more symbols with this change?
>>>
>> It does not change the number of symbols, in development, I already 
>> checked with original result with the new change. In -Xshare:dump, 
>> all symbols are permanent, I could add this back.
>>
>> + for (int i = 0; i < all_symbols->length(); i++) { + 
>> assert(all_symbols->at(i)->is_permanent(), "archived symbols must be 
>> permanent"); // <---- add here new line metaspaceShared.cpp: 1460 + 
>> all_symbols->at(i)->update_identity_hash();
>>         }
>>
>> Let me know if you need second webrev, or I will push with this adding.
>
> No need for another webrev. Do some testing with the assert before push.
>
> thanks,
>
> Calvin
>
>> Thanks
>> Yumin
>>> thanks,
>>>
>>> Calvin
>>>
>>> On 6/23/20 2:44 PM, Yumin Qi wrote:
>>>> Hi, Please review
>>>>
>>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8246181
>>>>
>>>> Webrev:http://cr.openjdk.java.net/~minqi/2020/8246181/webrev-00/
>>>>
>>>>
>>>> Summary: This is a little different from the bug suggested 
>>>> implementation. To avoid working the SymbolTable during dump, the 
>>>> symbol is added to a global array when it is created, 
>>>> SymbolTable::do_add_if_needed. The symbol only created once during 
>>>> its lifetime. There is just little performance overhead for runtime.
>>>>
>>>>
>>>> Tests: local jtreg on runtime/cds/appcds for debug/release.
>>>>
>>>> mach5: tier1,tier2,tier4
>>>>
>>>>
>>>> Thanks
>>>>
>>>> Yumin
>>>>