RFR: 8337505: Footprint and startup regressions up to 20% in GUI apps

[Daniel Gredler]

On Mon, 28 Oct 2024 21:26:38 GMT, Phil Race <prr at openjdk.org> wrote:

> https://bugs.openjdk.org/browse/JDK-8338677 already improved things for this so that's good.
> 
> This fix adds to it lazy initialisation of VarHandles in StrikeCache at the cost of some extra code.
> Since these VarHandles get used more or less immediately on Linux this new fix won't further improve matters there
> But should help on Mac where they aren't usually needed at startup
> And Windows is somewhere in between.

src/java.desktop/share/classes/sun/font/StrikeCache.java line 150:

> 148:     private static VarHandle imageHandle;
> 149: 
> 150:     private static VarHandle getXAdvanceHandle() {

Quick question: is there no concern with multi-threading / race conditions for these lazy creation methods? (e.g. requiring double-checked locking or similar)

This looks like a good use case for `StableValue`, if it were ready!

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PR Review Comment: https://git.openjdk.org/jdk/pull/21748#discussion_r1821157527