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Posted to jira@kafka.apache.org by GitBox <gi...@apache.org> on 2021/02/01 21:14:06 UTC

[GitHub] [kafka] abbccdda opened a new pull request #10017: KAFKA-12260: Avoid hitting NPE for partitionsFor

abbccdda opened a new pull request #10017:
URL: https://github.com/apache/kafka/pull/10017


   As mentioned in the ticket, returning `null` for `consumer#partitionsFor` is not a good client side agreement. Addressing this problem by returning the empty list instead.
   
   ### Committer Checklist (excluded from commit message)
   - [ ] Verify design and implementation 
   - [ ] Verify test coverage and CI build status
   - [ ] Verify documentation (including upgrade notes)
   


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[GitHub] [kafka] abbccdda commented on a change in pull request #10017: KAFKA-12260: Avoid hitting NPE for partitionsFor

Posted by GitBox <gi...@apache.org>.
abbccdda commented on a change in pull request #10017:
URL: https://github.com/apache/kafka/pull/10017#discussion_r568845018



##########
File path: clients/src/main/java/org/apache/kafka/clients/consumer/KafkaConsumer.java
##########
@@ -1948,7 +1948,7 @@ public OffsetAndMetadata committed(TopicPartition partition, final Duration time
             Timer timer = time.timer(timeout);
             Map<String, List<PartitionInfo>> topicMetadata = fetcher.getTopicMetadata(
                     new MetadataRequest.Builder(Collections.singletonList(topic), metadata.allowAutoTopicCreation()), timer);
-            return topicMetadata.get(topic);
+            return topicMetadata.getOrDefault(topic, Collections.emptyList());

Review comment:
       I don't think you could have a topic with 0 partition.




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[GitHub] [kafka] chia7712 commented on a change in pull request #10017: KAFKA-12260: Avoid hitting NPE for partitionsFor

Posted by GitBox <gi...@apache.org>.
chia7712 commented on a change in pull request #10017:
URL: https://github.com/apache/kafka/pull/10017#discussion_r568403080



##########
File path: clients/src/main/java/org/apache/kafka/clients/consumer/KafkaConsumer.java
##########
@@ -1948,7 +1948,7 @@ public OffsetAndMetadata committed(TopicPartition partition, final Duration time
             Timer timer = time.timer(timeout);
             Map<String, List<PartitionInfo>> topicMetadata = fetcher.getTopicMetadata(
                     new MetadataRequest.Builder(Collections.singletonList(topic), metadata.allowAutoTopicCreation()), timer);
-            return topicMetadata.get(topic);
+            return topicMetadata.getOrDefault(topic, Collections.emptyList());

Review comment:
       just curious.
   
   Is it possible that an existent topic has no partitions? If so, returning empty list may confuse users who querying nonexistent topic. Maybe we should throw ```UnknownTopicOrPartitionException``` for nonexistent topic and return empty list for existent topic.

##########
File path: clients/src/main/java/org/apache/kafka/clients/consumer/KafkaConsumer.java
##########
@@ -1948,7 +1948,7 @@ public OffsetAndMetadata committed(TopicPartition partition, final Duration time
             Timer timer = time.timer(timeout);
             Map<String, List<PartitionInfo>> topicMetadata = fetcher.getTopicMetadata(
                     new MetadataRequest.Builder(Collections.singletonList(topic), metadata.allowAutoTopicCreation()), timer);
-            return topicMetadata.get(topic);
+            return topicMetadata.getOrDefault(topic, Collections.emptyList());

Review comment:
       BTW, it is worth writing docs for this case (return empty list).




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[GitHub] [kafka] chia7712 commented on pull request #10017: KAFKA-12260: Avoid hitting NPE for partitionsFor

Posted by GitBox <gi...@apache.org>.
chia7712 commented on pull request #10017:
URL: https://github.com/apache/kafka/pull/10017#issuecomment-774852045


   @abbccdda Thanks for updating code. Two minor comments are left.
   
   1. The docs of ```KafkaConsumer#partitionsFor(String topic, Duration timeout)``` is not updated. 
   1. ```MockConsumer``` still return null when `topic` is nonexistent. Should we make it return empty collection as well?


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[GitHub] [kafka] abbccdda commented on a change in pull request #10017: KAFKA-12260: Avoid hitting NPE for partitionsFor

Posted by GitBox <gi...@apache.org>.
abbccdda commented on a change in pull request #10017:
URL: https://github.com/apache/kafka/pull/10017#discussion_r568845018



##########
File path: clients/src/main/java/org/apache/kafka/clients/consumer/KafkaConsumer.java
##########
@@ -1948,7 +1948,7 @@ public OffsetAndMetadata committed(TopicPartition partition, final Duration time
             Timer timer = time.timer(timeout);
             Map<String, List<PartitionInfo>> topicMetadata = fetcher.getTopicMetadata(
                     new MetadataRequest.Builder(Collections.singletonList(topic), metadata.allowAutoTopicCreation()), timer);
-            return topicMetadata.get(topic);
+            return topicMetadata.getOrDefault(topic, Collections.emptyList());

Review comment:
       I don't think you could have a topic with 0 partition.




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[GitHub] [kafka] abbccdda merged pull request #10017: KAFKA-12260: Avoid hitting NPE for partitionsFor

Posted by GitBox <gi...@apache.org>.
abbccdda merged pull request #10017:
URL: https://github.com/apache/kafka/pull/10017


   


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[GitHub] [kafka] abbccdda commented on pull request #10017: KAFKA-12260: Avoid hitting NPE for partitionsFor

Posted by GitBox <gi...@apache.org>.
abbccdda commented on pull request #10017:
URL: https://github.com/apache/kafka/pull/10017#issuecomment-775301979


   @chia7712 Sounds good


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[GitHub] [kafka] chia7712 commented on a change in pull request #10017: KAFKA-12260: Avoid hitting NPE for partitionsFor

Posted by GitBox <gi...@apache.org>.
chia7712 commented on a change in pull request #10017:
URL: https://github.com/apache/kafka/pull/10017#discussion_r568403080



##########
File path: clients/src/main/java/org/apache/kafka/clients/consumer/KafkaConsumer.java
##########
@@ -1948,7 +1948,7 @@ public OffsetAndMetadata committed(TopicPartition partition, final Duration time
             Timer timer = time.timer(timeout);
             Map<String, List<PartitionInfo>> topicMetadata = fetcher.getTopicMetadata(
                     new MetadataRequest.Builder(Collections.singletonList(topic), metadata.allowAutoTopicCreation()), timer);
-            return topicMetadata.get(topic);
+            return topicMetadata.getOrDefault(topic, Collections.emptyList());

Review comment:
       just curious.
   
   Is it possible that an existent topic has no partitions? If so, returning empty list may confuse users who querying nonexistent topic. Maybe we should throw ```UnknownTopicOrPartitionException``` for nonexistent topic and return empty list for existent topic.




----------------------------------------------------------------
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[GitHub] [kafka] chia7712 commented on a change in pull request #10017: KAFKA-12260: Avoid hitting NPE for partitionsFor

Posted by GitBox <gi...@apache.org>.
chia7712 commented on a change in pull request #10017:
URL: https://github.com/apache/kafka/pull/10017#discussion_r568411777



##########
File path: clients/src/main/java/org/apache/kafka/clients/consumer/KafkaConsumer.java
##########
@@ -1948,7 +1948,7 @@ public OffsetAndMetadata committed(TopicPartition partition, final Duration time
             Timer timer = time.timer(timeout);
             Map<String, List<PartitionInfo>> topicMetadata = fetcher.getTopicMetadata(
                     new MetadataRequest.Builder(Collections.singletonList(topic), metadata.allowAutoTopicCreation()), timer);
-            return topicMetadata.get(topic);
+            return topicMetadata.getOrDefault(topic, Collections.emptyList());

Review comment:
       BTW, it is worth writing docs for this case (return empty list).




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