RFR: 8243469: Lazily encode name in ZipFile.getEntryPos

[Lance Andersen]

Hi Claes,

Thank you for continuing to improve the performance in this part of java.util.zip.  The changes I think look pretty good. 

Best
Lance

> On Apr 23, 2020, at 8:34 AM, Claes Redestad <claes.redestad at oracle.com> wrote:
> 
> Hi,
> 
> current implementation of ZipFile.getEntryPos takes the encoded byte[]
> of the String we're looking up. Which means when looking up entries
> across multiple jar files, we allocate the byte[] over and over for each
> jar file searched.
> 
> If we instead refactor the internal hash table to use a normalized
> String-based hash value, we can almost always avoid both the repeated
> encoding and (most of) the hash calculation when the entry is not found
> in the jar/zip.
> 
> This realizes a significant startup improvement on applications with
> several or many jar files. A rather typical case. For example I see a
> 25% speedup of ZipEnty.getEntry calls on a Spring PetClinic, which
> reduces total startup time by ~120ms, or ~2.5% of total, on my setup. At
> the same time remaining neutral on single-jar apps.
> 
> Webrev: http://cr.openjdk.java.net/~redestad/8243469/open.00/
> Bug:    https://bugs.openjdk.java.net/browse/JDK-8243469
> 
> Testing: tier1-2
> 
> Thanks!
> 
> /Claes

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 <http://oracle.com/us/design/oracle-email-sig-198324.gif>Lance Andersen| Principal Member of Technical Staff | +1.781.442.2037
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