RFR: 8212136: Remove BaseSSLSocketImpl finalizer method [v2]

[Bradford Wetmore]

On Thu, 7 Apr 2022 20:17:28 GMT, Xue-Lei Andrew Fan <xuelei at openjdk.org> wrote:

>> Please review the update to remove finalizer method in the SunJSSE provider implementation.  It is one of the efforts to clean up the use of finalizer method in JDK.
>
> Xue-Lei Andrew Fan has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - typo blank linke correction
>  - revise the update

Thanks for the explanation: this is my first exposure to the `java.lang.ref.Cleaner` API, so am getting up to speed.  Sorry if these are dumb comments/questions.  

I see now what was being talked about in your other PR:  https://github.com/openjdk/jdk/pull/8136 and to not use a reference to `this` which would keep it from being GC'd.  I also see how you're keeping a cleaner object that has outside ("static") references to the actual things that need to be released, but don't we need to do the similar cleaning for the underlying Socket somehow?  What do Sockets do to make sure the underlying file descriptors/native memory are properly released? 

That said, we still need to send the close_notify at the TLS layer, right?  Simply removing the finalize() method is just going to silently shutdown the connection, and then the Socket is going to do whatever it does for finalization/Cleaning.

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PR: https://git.openjdk.java.net/jdk/pull/8065