[jdk25u] RFR: 8357959: (bf) ByteBuffer.allocateDirect initialization can result in large TTSP spikes

Fri Aug 22 13:47:31 UTC 2025

Hi all,

This pull request contains a backport of commit [e5ce5c57](https://github.com/openjdk/jdk/commit/e5ce5c57c83972ff52758a804c942986cab74ca7) from the [openjdk/jdk](https://git.openjdk.org/jdk) repository.

The commit being backported was authored by Rohitash Kumar on 12 Jun 2025 and was reviewed by Aleksey Shipilev and Alan Bateman.

Thanks!

Clean backport, confirmed that it has the desired effect on [reproducer](https://gist.github.com/rk-kmr/be4322b72a14ae04aeefc0260c01acf6).

Before: ~1000ms to reach safepoint
After: 0.2ms to reach safepoint

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Commit messages:
 - Backport e5ce5c57c83972ff52758a804c942986cab74ca7

Changes: https://git.openjdk.org/jdk25u/pull/125/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk25u&pr=125&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8357959
  Stats: 132 lines in 4 files changed: 115 ins; 0 del; 17 mod
  Patch: https://git.openjdk.org/jdk25u/pull/125.diff
  Fetch: git fetch https://git.openjdk.org/jdk25u.git pull/125/head:pull/125

PR: https://git.openjdk.org/jdk25u/pull/125