[lworld] RFR: 8377829: [lworld] SPECjvm2008:serial performance regression in comparing JDK27 mainline and valhalla default repo default mode(without --enable-preview)

[Roger Riggs]

On Fri, 13 Feb 2026 00:01:34 GMT, Sergey Kuksenko <skuksenko at openjdk.org> wrote:

> SPECjvm2008:serial shows a performance regression when comparing JDK27 mainline and valhalla default repo default mode (without --enable-preview). The regression is -10%-15% on all platforms.
> Rewriting ObjectInputStream from StreamAPI to loops and iterators allows restoring the performance.

Looks good, Thanks

src/java.base/share/classes/java/io/ObjectInputStream.java line 39:

> 37: import java.lang.reflect.Proxy;
> 38: import java.nio.charset.StandardCharsets;
> 39: import java.util.*;

Please restore the individual imports, wildcards are discouraged.

-------------

PR Review: https://git.openjdk.org/valhalla/pull/2097#pullrequestreview-3797466943
PR Review Comment: https://git.openjdk.org/valhalla/pull/2097#discussion_r2804389035