RFR: 8214712: Archive Attributes$Name.KNOWN_NAMES

David Holmes david.holmes at oracle.com
Tue Dec 4 05:09:52 UTC 2018

Hi Claes,

Meta-comment: are these Names candidates for the forthcoming 
compile-time evaluation of constants? Just wondering if these 
optimizations (and even the archiving itself) will be moot in the future?


On 4/12/2018 2:02 am, Claes Redestad wrote:
> Hi,
> initializing java.util.jar.Attributes.Name.<clinit> executes ~20k 
> bytecodes setting up and eagerly calculating case-insensitive hash codes 
> for a slew of Name objects.
> By archiving the resulting set of Names and initializing public 
> constants from the archived map, we reduce time spent starting up 
> (Name.<clinit> drops to 368 executed bytecodes) and improve the 
> footprint sharing effect of using CDS:
> http://cr.openjdk.java.net/~redestad/8214712/jdk.00/
> Testing: tier1-2 running
> Verified a 1-2.5ms startup improvement on java -jar Hello.jar
> - significant and stable reduction in instruction count, branches and 
> branch misses
> - only adds ~1.1Kb to the dumped CDS archive
> Thanks!
> /Claes

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