RFR: 8061254: SPECjvm2008-XML performance regressions in 9-b33
claes.redestad at oracle.com
Fri May 15 13:46:35 UTC 2015
On 2015-05-15 15:23, Alan Bateman wrote:
> On 13/05/2015 12:51, Claes Redestad wrote:
>> 9-b33 introduced a sustained regression in SPECjvm2008
>> xml.transform on a number of our test setups.
>> JDK-8058643 removed the check on value.length > 0, which
>> means repeated calls to "".hashCode() now do a store of the
>> calculated value (0) to the hash field. This has potential to
>> cause excessive cache coherence traffic in xml.transform
> I remember the original change but of course didn't spot that empty
> String would result in a write of 0. I like Shipilev's First Law.
Yes, this is a fine example of that law. :-)
> The patch looks good to me.
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