RFR: 8302845: Replace finalizer usage in JNDI DNS provider with Cleaner [v4]

[Daniel Fuchs]

On Tue, 9 May 2023 13:20:28 GMT, Aleksei Efimov <aefimov at openjdk.org> wrote:

>> JNDI `DnsClient` has a finalize method to close its internal datagram channel selector.
>>  The change proposed here replaces it with a cleaner to close the selector once the `DnsClient`
>>   instance becomes phantom reachable. 
>> 
>> The change was tested with `jdk-tier1` to `jdk-tier3` test sets which showed no failures.
>
> Aleksei Efimov 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 JDK-8302845_DNS_client_replace_finalizer
>  - Use cleanable to close the selector in DnsClient::close
>  - fix comment
>  - 8302845: Replace finalizer usage in JNDI DNS provider with Cleaner

LGTM

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Marked as reviewed by dfuchs (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/13837#pullrequestreview-1418680784