RFR: 8372409: java/net/httpclient/http3/H3MultipleConnectionsToSameHost.java timed out during warmup

[Daniel Fuchs]

On Wed, 26 Nov 2025 12:42:34 GMT, Volkan Yazici <vyazici at openjdk.org> wrote:

>> Yes - but if it happens here then the exchange will have been added to `exchanges` and therefore the Http3Connection will close it. It might not get marked as unprocessed and retried in that case - but that's a smaller issue. That's what I was trying to say in the comment stating that we need to double-check if the connection is still opened *after* having added the exchange to the exchange map. It is not an issue if the exchange is closed/cancelled more than once. The first call wins :-).
>
> `registerAndStartExchange()` is only called from `createHttp3ExchangeImpl()`, where there is the block holding the lock, just before the `registerAndStartExchange()` invocation. Would it be a good idea to obtain the `isOpen()` value there and pass it to `registerAndStartExchange()`?

No - as I said we need to do the check after updating the `exchanges` map - so specifically after this line:

exchanges.put(streamId, exchange);

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PR Review Comment: https://git.openjdk.org/jdk/pull/28494#discussion_r2565712867