[lworld] RFR: 8377829: [lworld] SPECjvm2008:serial performance regression in comparing JDK27 mainline and valhalla default repo default mode(without --enable-preview) [v2]

[Sergey Kuksenko]

> 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.

Sergey Kuksenko has updated the pull request incrementally with one additional commit since the last revision:

  restore individual import

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

Changes:
  - all: https://git.openjdk.org/valhalla/pull/2097/files
  - new: https://git.openjdk.org/valhalla/pull/2097/files/092f59b9..dd78bb73

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=valhalla&pr=2097&range=01
 - incr: https://webrevs.openjdk.org/?repo=valhalla&pr=2097&range=00-01

  Stats: 6 lines in 1 file changed: 4 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/valhalla/pull/2097.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/2097/head:pull/2097

PR: https://git.openjdk.org/valhalla/pull/2097