RFR: 6988220: java.lang.ObjectName use of String.intern() causes major performance issues at scale

David Holmes david.holmes at oracle.com
Thu Feb 23 21:53:05 UTC 2012

Hi Fred,

java.lang.ObjectName? :) Need to fix that.

So often we intern strings precisely so that equals() can use == to 
improve performance.

It seems to me that this is a case of "fixing" something for one 
use-case without knowing what the impact will be on other use-cases!

Is there perhaps a solution that makes String.intern more scalable?


On 24/02/2012 1:36 AM, Frederic Parain wrote:
> This a simple fix to solve CR 6988220:
> http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6988220
> The use of String.intern() in the ObjectName class prevents
> the class the scale well when more than 20K ObjectNames are
> managed. The fix simply removes the use of String.intern(),
> and uses regular String instead. The Object.equals() method
> is modified too to make a regular String comparison. The
> complexity of this method now depends on the length of
> the ObjectName's canonical name, and is not impacted any
> more by the number of ObjectName instances being handled.
> The Webrev:
> http://cr.openjdk.java.net/~fparain/6988220/webrev.00/
> I've tested this fix with the jdk_lang and jdk_management
> test suites.
> Thanks,
> Fred

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