[GitHub] [kafka] rajinisivaram commented on a change in pull request #10022: KAFKA-12268; Return from KafkaConsumer.poll only when records available or timeout

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rajinisivaram commented on a change in pull request #10022:
URL: https://github.com/apache/kafka/pull/10022#discussion_r569292052



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File path: clients/src/main/java/org/apache/kafka/clients/consumer/KafkaConsumer.java
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@@ -1236,7 +1236,7 @@ public void assign(Collection<TopicPartition> partitions) {
                 }
 
                 final FetchedRecords<K, V> records = pollForFetches(timer);
-                if (!records.isEmpty()) {
+                if (!records.records().isEmpty()) {

Review comment:
       Fixing system tests would be straightforward, but as @chia7712 said, this could impact existing applications which rely on the current behaviour. For example, applications may `poll(longTimeout)` and exit if no records are returned, treating it as an error condition, similar to system tests. Adding a new API with options sounds like the safe alternative to maintain compatibility. But it may be good to follow up on the mailing list, perhaps on the discussion thread  of KIP-695 to get wider opinion. Anyway the change proposed in this PR seems unsuitable, we can either fix system tests or make the new behaviour optional.




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