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

[Volkan Yazici]

On Wed, 26 Nov 2025 12:33:25 GMT, Daniel Fuchs <dfuchs at openjdk.org> wrote:

>> src/java.net.http/share/classes/jdk/internal/net/http/Http3Connection.java line 555:
>> 
>>> 553:             // only start the exchange if the connection is
>>> 554:             // still open
>>> 555:             exchange.start();
>> 
>> Given `isOpen()` and `exchange.start()` are not run while the lock is held, isn't there still, yet slight, a chance that the connection is closed before the `exchange.start()` invocation?
>
> 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()`?

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PR Review Comment: https://git.openjdk.org/jdk/pull/28494#discussion_r2564862070