RFR: 8201179: Regression due loading java.nio.charset.StandardCharsets during bootstrap

[Ulf Zibis]

Maybe have a DefaultCharsets or StartupCharsets provider?

-Ulf


Am 09.04.2018 um 18:47 schrieb Martin Buchholz:
> Thanks, Claes.
>
> I like very much how you've been reducing java startup every release, 
> but ...
> I'm bothered by the small but eternal overhead of the INSTANCE fields ...
> It looks like the UTF_16* charsets don't need INSTANCE fields since 
> they will not be referenced anywhere else in java.base - can we at 
> least get rid of those, despite the asymmetry?
>
> A heroic optimization would be to create a StandardCharsets with only 
> the 3 special fields and then somehow retransform the class to add 
> some more final static fields after phase1 is over (but I have no idea 
> what it would take).
>
> On Mon, Apr 9, 2018 at 6:45 AM, Claes Redestad 
> <claes.redestad at oracle.com <mailto:claes.redestad at oracle.com>> wrote:
>
>     Hi,
>
>     JDK-8200310 cleaned up java.nio.charset.StandardCharsets to not
>     use Charset.forName, but also removed the optimization to have
>     unconditionally loaded charsets set up static INSTANCE constants,
>     which means that many systems the
>     java.nio.charset.StandardCharsets will be initialized in
>     System.initPhase1.
>
>     This should be avoided since at this point the VM is just booting
>     up and any code executed delays initialization of JIT etc.
>
>     Webrev: http://cr.openjdk.java.net/~redestad/8201179/open.00/
>     <http://cr.openjdk.java.net/%7Eredestad/8201179/open.00/>
>     Bug: https://bugs.openjdk.java.net/browse/JDK-8201179
>     <https://bugs.openjdk.java.net/browse/JDK-8201179>
>
>     This patch makes all the constants in j.n.c.StandardCharsets use
>     new INSTANCE fields of each respective Charset and adds some
>     comments as to why they exist.
>
>     I also think we should avoid depending on j.n.c.StandardCharsets
>     within java.base as to not accidentally execute more code in
>     initPhase1 than absolutely necessary, so I've changed uses in core
>     packages (java.lang, java.util, java.zip...) to use the internal
>     alternative.
>
>     Thanks!
>
>     /Claes
>
>

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