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

[Yumin Qi]

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.

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
>>