RFR: 7133138 Improve io performance around timezone lookups

[Masayoshi Okutsu]

The fix looks good.

Thanks,
Masayoshi

On 2/22/2012 3:19 AM, Seán Coffey wrote:
> I've worked with Masayoshi on this issue. Hoping to push to JDK8 and 
> backport to 7u and a jdk6 once baked for a while.
>
> Some windows boxes were showing performance issues when attempting to 
> iterate through all available timezones available in the JRE. Changes 
> made here should reduce the amount of file stat calls made on 
> jre/lib/zi/* files.  Tweaks are made to the alias table also to reduce 
> number of aliases that require lookup.
>
> All TZ regression tests run without issue. I've seen a 20-30% speed up 
> on iteration of timezones on windows as a result. Unix doesn't appear 
> to suffer as badly from such a file IO hit.
>
> http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7133138
> http://cr.openjdk.java.net/~coffeys/webrev.7133138/
>
> regards,
> Sean.
>