KAFKA-10357: Extract setup of changelog from Streams partition assignor by cadonna · Pull Request #10163 · apache/kafka

cadonna · 2021-02-19T16:54:03Z

To implement the explicit user initialization of Kafka Streams as
described in KIP-698, we first need to extract the code for the
setup of the changelog topics from the Streams partition assignor
so that it can also be called outside of a rebalance.

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Verify design and implementation
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cadonna · 2021-02-19T16:58:21Z

+    public Set<TopicPartition> preExistingNonSourceTopicBasedPartitions() {
+        return Collections.unmodifiableSet(preExistingNonSourceTopicBasedChangelogPartitions);
+    }
+
+    public Set<TopicPartition> preExistingPartitionsFor(final TaskId taskId) {
+        if (preExistingChangelogPartitionsForTask.containsKey(taskId)) {
+            return Collections.unmodifiableSet(preExistingChangelogPartitionsForTask.get(taskId));
+        }
+        return Collections.emptySet();
+    }
+
+    public Set<TopicPartition> sourceTopicBasedPartitions() {
+        return Collections.unmodifiableSet(sourceTopicBasedChangelogTopicPartitions);
+    }
+
+    public Set<TaskId> taskIds() {
+        return Collections.unmodifiableSet(changelogPartitionsForTask.keySet());
+    }


I added some methods to simplify some code in the assignor.

cadonna · 2021-02-19T17:05:03Z

-                                                         final Map<TopicPartition, ListOffsetsResultInfo> endOffsets,
+    private Map<TaskId, Long> computeEndOffsetSumsByTask(final Map<TopicPartition, ListOffsetsResultInfo> endOffsets,
                                                         final Map<TopicPartition, Long> sourceChangelogEndOffsets,
-                                                         final Collection<TopicPartition> newlyCreatedChangelogPartitions) {


I removed the newly created changelog partitions because they do actually not contribute to the task end offset sums.

cadonna · 2021-02-19T17:06:31Z

Call for review: @ableegoldman @guozhangwang @stevenpyzhang

guozhangwang

Made a quick pass on the PR and it lgtm overall. Leaving to @ableegoldman and @mjsax to merge.

ableegoldman

Thanks Bruno! Some naming suggestions since this code is pretty dense, but overall LGTM

ableegoldman · 2021-02-26T20:44:29Z

+        log = logContext.logger(getClass());
+    }
+
+    public void setup() {


Is there a specific reason we need to make an explicit call to setup() rather than just doing this in the constructor? I'm always worried we'll end up forgetting to call setup again after some refactoring and someone will waste a day debugging their code because they tried to use a Changelogs object before/without first calling setup()

I agree with you and if I remember correctly you brought this up also on my change that introduces RepartitionTopics. Once we have the explicit user initialisation as described in KIP-698, we need to distinguish between setting up the broker-side state for Streams and verifying the the broker-side change. That requires changes in the InternalTopicManager. Currently, I could not separate this two concerns and left both in the setup method. Moving forward I will put everything that can be initialized in the constructor to avoid the mistakes you refer to. Consider the state of this class a temporary situation that will be soon fixed.

Sounds good 🙂

ableegoldman · 2021-03-02T03:52:04Z

+    private final InternalTopicManager internalTopicManager;
+    private final Map<Integer, TopicsInfo> topicGroups;
+    private final Map<Integer, Set<TaskId>> tasksForTopicGroup;
+    private final Map<TaskId, Set<TopicPartition>> changelogPartitionsForTask = new HashMap<>();


nit: clarify that this contains only stateful tasks (eg changelogPartitionsForStatefulTask -- for this and any other data structure which only contains stateful partitions/tasks

I also thought about this and came to the conclusion that it would be clear that the task is stateful since it has at least one changelog. But I am fine with renaming it as you proposed. Better clear!

ableegoldman · 2021-03-02T03:55:58Z

+                    if (!sourceTopicBasedChangelogTopics.contains(topicPartition.topic())) {
+                        preExistingNonSourceTopicBasedChangelogPartitions.add(topicPartition);
+                    } else {
+                        sourceTopicBasedChangelogTopicPartitions.add(topicPartition);


So technically this only contains pre-existing source topic based changelogs -- can we specify so in the set name? It's already pretty long but maybe we can drop the Topic part to help somewhat

Also here, if a changelog is source based it has to be pre-existing, because the InternalTopicManager will not setup source topics. However, making this clearer in the name does not harm.

ableegoldman · 2021-03-02T04:01:47Z

-                    changelogEndOffset = sourceChangelogEndOffsets.get(changelog);
-                } else if (endOffsets.containsKey(changelog)) {
-                    changelogEndOffset = endOffsets.get(changelog).offset();
+        for (final TaskId taskId : changelogTopics.taskIds()) {


Just to clarify, changelogTopics.taskIds() will only return stateful tasks -- again I think we should clarify that in the getter method name. I had to trace back through the code to be sure

ableegoldman

Looks good, merging to trunk

ableegoldman · 2021-03-02T19:59:20Z

Java11 failed with unrelated flaky kafka.server.ListOffsetsRequestTest.testResponseIncludesLeaderEpoch, Java15 failed with Execution failed for task ':streams:test-utils:unitTest' (this PR does not touch on the test-utils so this failure should be unrelated, however I ran them locally to verify)

* apache-github/trunk: (37 commits) KAFKA-10357: Extract setup of changelog from Streams partition assignor (apache#10163) KAFKA-10251: increase timeout for consuming records (apache#10228) KAFKA-12394; Return `TOPIC_AUTHORIZATION_FAILED` in delete topic response if no describe permission (apache#10223) MINOR: Disable transactional/idempotent system tests for Raft quorums (apache#10224) KAFKA-10766: Unit test cases for RocksDBRangeIterator (apache#9717) KAFKA-12289: Adding test cases for prefix scan in InMemoryKeyValueStore (apache#10052) KAFKA-12268: Implement task idling semantics via currentLag API (apache#10137) MINOR: Time and log producer state recovery phases (apache#10241) MINOR: correct the error message of validating uint32 (apache#10193) MINOR: Format the revoking active log output in `StreamsPartitionAssignor` (apache#10242) KAFKA-12323 Follow-up: Refactor the unit test a bit (apache#10205) MINOR: Remove stack trace of the lock exception in a debug log4j (apache#10231) MINOR: Word count should account for extra whitespaces between words (apache#10229) MINOR; Small refactor in `GroupMetadata` (apache#10236) KAFKA-10340: Proactively close producer when cancelling source tasks (apache#10016) KAFKA-12329; kafka-reassign-partitions command should give a better error message when a topic does not exist (apache#10141) KAFKA-12254: Ensure MM2 creates topics with source topic configs (apache#10217) MINOR: fix kafka-metadata-shell.sh (apache#10226) KAFKA-12374: Add missing config sasl.mechanism.controller.protocol (apache#10199) KAFKA-10101: Fix edge cases in Log.recoverLog and LogManager.loadLogs (apache#8812) ...

cadonna added 2 commits February 19, 2021 17:52

KAFKA-10357: Extract setup of changelog from Streams partition assignor

43c7dad

Add missing files and fix indentation

bca36d3

cadonna commented Feb 19, 2021

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guozhangwang reviewed Feb 23, 2021

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mjsax added kip Requires or implements a KIP streams labels Feb 23, 2021

ableegoldman reviewed Mar 2, 2021

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cadonna added 2 commits March 2, 2021 14:08

Include feedback

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Remove superfluous spaces

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ableegoldman approved these changes Mar 2, 2021

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ableegoldman merged commit a848e0c into apache:trunk Mar 2, 2021

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cadonna commented Feb 19, 2021

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cadonna Mar 2, 2021 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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cadonna Mar 2, 2021 •

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