Unexpected behaviour for asynchronous doSend-Call

[agering-hmmh]

doSend() returns CompletableFuture

Expectation: sending is async and all errors are handled as CompletableFuture.exceptionally()

Reality:

• the Call is synchronous, Timeout blocks the application (caller needs to use @Async),
• Timeout causes a runtime exception outside of CompletableFuture, so the caller needs a try catch to handle all possible exceptions, otherwise where is status 500, although CompletableFuture.exceptionally defined

[artembilan]

This is how KafkaProducer.send() works. It is blocked on the waitOnMetadata():

          ClusterAndWaitTime clusterAndWaitTime;
            try {
                clusterAndWaitTime = waitOnMetadata(record.topic(), record.partition(), nowMs, maxBlockTimeMs);
            } catch (KafkaException e) {
                if (metadata.isClosed())
                    throw new KafkaException("Producer closed while send in progress", e);
                throw e;
            }

That is not what we can control some way on KafkaTemplate.