[jdk20u] RFR: 8307425: Socket input stream read burns CPU cycles with back-to-back poll(0) calls

Wed May 17 18:23:53 UTC 2023

Backport the fix for [JDK-8307425](https://bugs.openjdk.org/browse/JDK-8307425) from openjdk/jdk to jdk20u.
This is a clean backport.

It fixes places in NIO where nanoseconds are rounded down to milliseconds, leading to expensive tight poll/read loops in some scenarios - where for instance a 1ms timeout was supplied.

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Commit messages:
 - Backport 73ac710533a45bf5ba17f308aa49556b877b8bf9

Changes: https://git.openjdk.org/jdk20u/pull/80/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk20u&pr=80&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8307425
  Stats: 22 lines in 3 files changed: 20 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk20u/pull/80.diff
  Fetch: git fetch https://git.openjdk.org/jdk20u.git pull/80/head:pull/80

PR: https://git.openjdk.org/jdk20u/pull/80