RFR: 8365292: Remove javax.imageio.spi.ServiceRegistry.finalize()

[Sergey Bylokhov]

On Tue, 12 Aug 2025 19:32:33 GMT, Phil Race <prr at openjdk.org> wrote:

> Remove javax.imageio.spi.ServiceRegistry.finalize() since it is deprecated for removal.
> The impact of this should be minimal. The IIORegistry will now be a singleton - which it already was 
> in practice since Applets are no longer supported. Since it is a singleton, it will persist for the life
> of the VM, so will never be garbage collected.
> A test that verifies one per-AppContext is now obsolete, and is deleted, and there's no good reason to make it a negative test, since in due course AppContext itself will be deleted and is un-used today except in tests.
> 
> Since JDK 9, ServiceRegistry has supported only Image I/O specified providers, and since the IIORegistry does this,
> in practice there is very little reason for an application to create instances or subclasses of it.
> And even if they do, typically like IIORegistry, they be used for the life time of the application.
> And if they are collected, without calling ServiceRegistry.deregisterAll() there may be no impact,
> since only providers that implement RegisterableService will be affected.
> 
> See the JBS issue for all the details.
> 
> The CSR is ready for review https://bugs.openjdk.org/browse/JDK-8365409

src/java.desktop/share/classes/javax/imageio/spi/IIORegistry.java line 109:

> 107:     private static final IIORegistry registry;
> 108:     static {
> 109:         registry = new IIORegistry();

Constructor of IIORegistry executes a large amount of code, might be better to load it lazily as before? instead of from the class initialization. could be a good opportunity to use StableValue?

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PR Review Comment: https://git.openjdk.org/jdk/pull/26752#discussion_r2277756129