RFR: JDK-8276422 Add command-line option to disable finalization

[Aleksey Shipilev]

On Thu, 18 Nov 2021 07:13:55 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> Huh, good catch! This was mostly left over from an earlier version of the flag that used system properties, which aren't initialized until after the Finalizer class is initialized.
>> 
>> It might be the case that the Holder can be removed at this point, since the finalization-enabled bit is no longer in a system property and is in a native class member that should be available before the VM is started.
>> 
>> I say "might" though because this occurs early in system startup, and weird things potentially happen. For example, suppose the first object with a finalizer is created before the Finalizer class is initialized. The VM will perform an upcall to Finalizer::register. An ordinary call to a static method will ensure the class is initialized before proceeding with the call, but this VM upcall is a special case.... I'll have to investigate this some more.
>
> @stuart-marks not sure I see how anything is different here compared to the existing logic. The `Finalizer` class is explicitly initialized quite early in the init process, but if a preceding class's initialization created an object with a finalizer then that same upcall would be involved.

Do we even have to have a flag on Java side? It looks like these calls are only done as the upcalls from VM, so we might just keep the flag on VM side?

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PR: https://git.openjdk.java.net/jdk/pull/6442