RFR: 8355319: Update Manpage for Compact Object Headers (Production)

[David Holmes]

On Wed, 28 May 2025 11:30:46 GMT, Roman Kennke <rkennke at openjdk.org> wrote:

> Adds an entry for -XX:+UseCompactObjectHeaders in the manpage for the java command, under 'Advanced runtime options'.

Changes requested by dholmes (Reviewer).

src/java.base/share/man/java.md line 1026:

> 1024: :   Enables compact object headers. By default, this option is disabled.
> 1025:     Enabling this option reduces memory footprint in the Java heap by
> 1026:     4 bytes per object (on average).

The options are (with 3 exceptions) in alphabetical order - please move this to  where the other `UseXXX` flags are.

This does not explain at all why someone would want to use, or not use, COH. What are the trade-offs for turning it on? Please explain the usage.

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PR Review: https://git.openjdk.org/jdk/pull/25491#pullrequestreview-2890254926
PR Review Comment: https://git.openjdk.org/jdk/pull/25491#discussion_r2122379295