mjsax commented on code in PR #18587:
URL: https://github.com/apache/kafka/pull/18587#discussion_r1920894860
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clients/src/main/java/org/apache/kafka/clients/producer/KafkaProducer.java:
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@@ -1134,6 +1129,13 @@ private ClusterAndWaitTime waitOnMetadata(String topic,
Integer partition, long
return new ClusterAndWaitTime(cluster, elapsed);
}
+ private String getErrorMessage(Integer partitionsCount, String topic,
Integer partition, long maxWaitMs) {
+ return partitionsCount == null ?
+ String.format("Topic %s not present in metadata after %d ms.",
+ topic, maxWaitMs) :
+ String.format("Partition %d of topic %s with partition count %d is
not present in metadata after %d ms.",
+ partition, topic, partitionsCount, maxWaitMs);
+ }
Review Comment:
> Is there any value in including the partition value in the error message
if it's non-null?
Yes. `partition` is an input parameter to the method, and it's only `null`
if the caller does not care about the metadata of a specific partitions (as
pointed out by Andrew). So it's if not-null, the user cares and we should log
it.
If `partition != null`, it helps to identify the case of a non-existing
partition the user wants to write into. Assume a topic with 4 partitions, and
user specific partition 5 as explicit argument when calling `send()`. The
producer would try to learn about the leader broker for partition 5, but it
does not exist, and it would loop until `max.block.ms` is exhausted and finally
fail with: `Partition 5 of topic <FOO> with partition count 4 is not present in
metadata after XXX ms.` -- Then we can suspect that the topic may really only
have 4 partitions... W/o `Partition 5` it's totally unclear why the metadata
could not be found and why we hit `max.block.ms` on `send()`; the generic error
`Topic %s not present in metadata after %d ms.` does not help us to identify
this case.
Or did you mean, if `partition == null`? For this case, I agree it's not
really helpful to log `partition` (as the user does not care anyway), but it
think we don't log it anyway given the current code... (cf below)
> Seems to me that 3 messages would be best so that we never get a "null" as
an ugly insert. wdyt?
I believe the code is correct as-is. There is only two cases:
1. `partition == null`. If we get metadata successfully, it implies that
`partitionCount != null` and we just move on and don't throw
`TimeoutException`. If we cannot get any metadata for the topic, we stay with
`partitionCount == null` and use `Topic %s not present in metadata after %d
ms.` for the `TimeoutException`.
2. `partition != null`. For this case, if we get metadata successfully, we
have a `partitionCount`, but we might still fail, if we don't get the metadata
for the specified partition. For this case, we would use `Partition %d of topic
%s with partition count %d is not present in metadata after %d ms` as error
message. The other failure case is, that we don't get any metadata for the
topic at all, and thus `partitionCount == null` and we still log the right
thing. The fact that `partition != null` does not matter if `partitionCount ==
null`.
Hence, case (3) is not an error case... If we did get metadata
(`partitionCount != null`) and if the user does not care (`partition == null`),
we will never throw `TimeoutException`.
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