RFR: 8330940: Impossible to create a socket backlog greater than 200 on Windows 8+ [v2]

[Jaikiran Pai]

On Mon, 16 Jun 2025 11:16:55 GMT, Daniel Fuchs <dfuchs at openjdk.org> wrote:

>> Jaikiran Pai has updated the pull request incrementally with four additional commits since the last revision:
>> 
>>  - include a test for AsynchronousServerSocketChannel
>>  - System.err instead of System.out
>>  - trim down code comment
>>  -  > 200 instead of >= 200
>
> test/jdk/java/net/ServerSocket/LargeBacklogTest.java line 96:
> 
>> 94:                 // do not attempt any more connections
>> 95:                 break;
>> 96:             }
> 
> hmm... interesting: so we don't need to leave the socket open to increase the backlog. I guess the server side has to accept the socket and read the FIN, so the backlog won't be decremented until the socket is accepted (even if it's already closed on the client side).

That's a good question. The current behaviour (on Windows and *nix) is that, closing the Socket which initiated the connection doesn't affect the number of connections that were put into a pending queue (backlog) on the server side. I will need to read up a bit to see if that is specified or if it is merely an implementation detail.

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PR Review Comment: https://git.openjdk.org/jdk/pull/25819#discussion_r2151785668