RFR: 8349107: Remove RMI finalizers [v2]

[Stuart Marks]

On Mon, 3 Feb 2025 19:13:10 GMT, Brent Christian <bchristi at openjdk.org> wrote:

>> 3 finalizers in RMI code can be removed, as they do not perform meaningful cleanup.
>> 
>> **`jdk.naming.rmi/share/classes/com/sun/jndi/rmi/registry/RegistryContext`**
>> 
>> `RegistryContext.finalize()` just calls `close()`. The `close()` method does not perform any cleanup per se, but rather "helps the garbage collector" by setting `environment` and `registry` to `null`.
>> 
>> 
>> **`jdk.naming.rmi/share/classes/com/sun/jndi/rmi/registry/RegistryContext.BindingEnumeration`**
>> 
>> `BindingEnumeration.finalize()` simply calls `close()` on the `ctx` field, itself a `RegistryContext` (and `close()` just "helps the GC.")
>> 
>> 
>> **`src/java.rmi/share/classes/sun/rmi/log/LogInputStream`**
>> 
>> `LogInputStream` tracks its length with an int field, `length`. If `length` ever becomes == 0, `LogInputStream`'s methods will return without doing anything.
>> 
>> The finalizer calls `close()`, which just sets length = 0.
>> 
>> By the time a `LogInputStream` becomes unreachable and is finalized, it's a moot point whether length == 0, as no more methods can be called.
>> If anything, this finalizer could cause a bug. If a `LogInputStream` were to became unreachable while a method were still running, the finalizer could set the length to 0 while method code is still running and expecting a length != 0.
>> It's possible that there is a very long standing bug that `close()` should be calling `in.close()`, in which case this evaluation will need to be revisited.
>
> Brent Christian has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains four additional commits since the last revision:
> 
>  - Merge branch 'master' into rmF10Nnow
>  - Remove finalizer from RMI LogInputStream
>  - Remove finalizer from RMI RegistryContext.BindingEnumeration
>  - Remove finalizer from RMI RegistryContext

> It's possible that there is a very long standing bug that close() should be calling in.close(), in which case this evaluation will need to be revisited.

I don't think this is an issue. The only user of LogInputStream appears to be in [ReliableLog](https://github.com/openjdk/jdk/blob/bad39b6d8892ba9b86bc81bf01108a1df617defb/src/java.rmi/share/classes/sun/rmi/log/ReliableLog.java#L754), which creates an input stream, wraps it in a LogInputStream one or more times, and then closes the input stream in a finally-block. Thus LogInputStream isn't responsible for closing the input stream.

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PR Comment: https://git.openjdk.org/jdk/pull/23406#issuecomment-2634747157