RFR: 8372159: HttpClient SelectorManager thread could be a VirtualThread [v6]

[Daniel Jeliński]

On Mon, 24 Nov 2025 12:13:14 GMT, Daniel Fuchs <dfuchs at openjdk.org> wrote:

>> Each HttpClient instance creates an additional platform thread for its SelectorManager. With recent updates to NIO/VirtualThreads that thread could now become a VirtualThread. This would avoid having each HttpClient instance use up one platform thread.
>> This is similar to what was done for the HttpClient QuicSelectorThread in [JDK-8369920](https://bugs.openjdk.org/browse/JDK-8369920).
>> This should be transparent for users of the API. 
>> An undocumented internal system property is introduced that can revert the change in case of unforeseen trouble.
>
> Daniel Fuchs has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Update test/jdk/java/net/httpclient/http3/H3QuicVTTest.java
>   
>   Co-authored-by: Daniel Jelinski <djelinski1 at gmail.com>

Marked as reviewed by djelinski (Reviewer).

-------------

PR Review: https://git.openjdk.org/jdk/pull/28395#pullrequestreview-3500115661