[GitHub] [kafka] chia7712 commented on a change in pull request #10022: KAFKA-12268; Return from KafkaConsumer.poll only when records available or timeout

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chia7712 commented on a change in pull request #10022:
URL: https://github.com/apache/kafka/pull/10022#discussion_r569105085



##########
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:
       not sure whether this is a kind of behavior change. The docs of ```KafkaConsumer#poll``` indicates that ```timeout``` is used to wait available records.
   
   ```
        * This method returns immediately if there are records available. Otherwise, it will await the passed timeout.
        * If the timeout expires, an empty record set will be returned. Note that this method may block beyond the
        * timeout in order to execute custom {@link ConsumerRebalanceListener} callbacks.
   ```
   
   Maybe we can introduce a new API ```poll(Duration, Options)``` (similar to KafkaAdmin. The options enables us to adjust the poll behavior for specific use cases. Also, it opens a room to give various ```poll``` in the future.




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