[
https://issues.apache.org/jira/browse/FLINK-4280?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15865859#comment-15865859
]
ASF GitHub Bot commented on FLINK-4280:
---------------------------------------
Github user rmetzger commented on a diff in the pull request:
https://github.com/apache/flink/pull/2509#discussion_r101047374
--- Diff:
flink-connectors/flink-connector-kafka-base/src/test/java/org/apache/flink/streaming/connectors/kafka/FlinkKafkaConsumerBaseMigrationTest.java
---
@@ -299,91 +131,60 @@ public Object answer(InvocationOnMock
invocationOnMock) throws Throwable {
testHarness.setTimeCharacteristic(TimeCharacteristic.ProcessingTime);
testHarness.setup();
+ // restore state from binary snapshot file using legacy method
testHarness.initializeStateFromLegacyCheckpoint(
getResourceFilename("kafka-consumer-migration-test-flink1.1-snapshot"));
testHarness.open();
- final Throwable[] error = new Throwable[1];
+ // assert that there are partitions and is identical to
expected list
+ Assert.assertTrue(consumerFunction.getSubscribedPartitions() !=
null);
+
Assert.assertTrue(!consumerFunction.getSubscribedPartitions().isEmpty());
+ Assert.assertEquals(partitions,
consumerFunction.getSubscribedPartitions());
- // run the source asynchronously
- Thread runner = new Thread() {
- @Override
- public void run() {
- try {
- consumerFunction.run(new
DummySourceContext() {
- @Override
- public void collect(String
element) {
- //latch.trigger();
- }
- });
- }
- catch (Throwable t) {
- t.printStackTrace();
- error[0] = t;
- }
- }
- };
- runner.start();
+ // the expected state in
"kafka-consumer-migration-test-flink1.1-snapshot"
+ final HashMap<KafkaTopicPartition, Long> expectedState = new
HashMap<>();
+ expectedState.put(new KafkaTopicPartition("abc", 13), 16768L);
+ expectedState.put(new KafkaTopicPartition("def", 7),
987654321L);
- if (!latch.isTriggered()) {
- latch.await();
- }
+ // assert that state is correctly restored from legacy
checkpoint
+ Assert.assertTrue(consumerFunction.getRestoredState() != null);
+ Assert.assertEquals(expectedState,
consumerFunction.getRestoredState());
consumerOperator.close();
-
- runner.join();
-
- Assert.assertNull(error[0]);
- }
-
- private abstract static class DummySourceContext
- implements SourceFunction.SourceContext<String> {
-
- private final Object lock = new Object();
-
- @Override
- public void collectWithTimestamp(String element, long
timestamp) {
- }
-
- @Override
- public void emitWatermark(Watermark mark) {
- }
-
- @Override
- public Object getCheckpointLock() {
- return lock;
- }
-
- @Override
- public void close() {
- }
--- End diff --
Looks like you've removed a lot of code from this test here. I guess that
the `DummyFlinkKafkaConsumer` covers everything the deleted code did?
> New Flink-specific option to set starting position of Kafka consumer without
> respecting external offsets in ZK / Broker
> -----------------------------------------------------------------------------------------------------------------------
>
> Key: FLINK-4280
> URL: https://issues.apache.org/jira/browse/FLINK-4280
> Project: Flink
> Issue Type: New Feature
> Components: Kafka Connector
> Reporter: Tzu-Li (Gordon) Tai
> Assignee: Tzu-Li (Gordon) Tai
> Fix For: 1.3.0
>
>
> Currently, to start reading from the "earliest" and "latest" position in
> topics for the Flink Kafka consumer, users set the Kafka config
> {{auto.offset.reset}} in the provided properties configuration.
> However, the way this config actually works might be a bit misleading if
> users were trying to find a way to "read topics from a starting position".
> The way the {{auto.offset.reset}} config works in the Flink Kafka consumer
> resembles Kafka's original intent for the setting: first, existing external
> offsets committed to the ZK / brokers will be checked; if none exists, then
> will {{auto.offset.reset}} be respected.
> I propose to add Flink-specific ways to define the starting position, without
> taking into account the external offsets. The original behaviour (reference
> external offsets first) can be changed to be a user option, so that the
> behaviour can be retained for frequent Kafka users that may need some
> collaboration with existing non-Flink Kafka consumer applications.
> How users will interact with the Flink Kafka consumer after this is added,
> with a newly introduced {{flink.starting-position}} config:
> {code}
> Properties props = new Properties();
> props.setProperty("flink.starting-position", "earliest/latest");
> props.setProperty("auto.offset.reset", "..."); // this will be ignored (log a
> warning)
> props.setProperty("group.id", "...") // this won't have effect on the
> starting position anymore (may still be used in external offset committing)
> ...
> {code}
> Or, reference external offsets in ZK / broker:
> {code}
> Properties props = new Properties();
> props.setProperty("flink.starting-position", "external-offsets");
> props.setProperty("auto.offset.reset", "earliest/latest"); // default will be
> latest
> props.setProperty("group.id", "..."); // will be used to lookup external
> offsets in ZK / broker on startup
> ...
> {code}
> A thing we would need to decide on is what would the default value be for
> {{flink.starting-position}}.
> Two merits I see in adding this:
> 1. This compensates the way users generally interpret "read from a starting
> position". As the Flink Kafka connector is somewhat essentially a
> "high-level" Kafka consumer for Flink users, I think it is reasonable to add
> Flink-specific functionality that users will find useful, although it wasn't
> supported in Kafka's original consumer designs.
> 2. By adding this, the idea that "the Kafka offset store (ZK / brokers) is
> used only to expose progress to the outside world, and not used to manipulate
> how Kafka topics are read in Flink (unless users opt to do so)" is even more
> definite and solid. There was some discussion in this PR
> (https://github.com/apache/flink/pull/1690, FLINK-3398) on this aspect. I
> think adding this "decouples" more Flink's internal offset checkpointing from
> the external Kafka's offset store.
--
This message was sent by Atlassian JIRA
(v6.3.15#6346)
