Shawyeok opened a new pull request #14317:
URL: https://github.com/apache/pulsar/pull/14317
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### Motivation
If a message reached maxRedeliverCount, it will send to deadLetterTopic,
since `2.8.0`, this mechanism is **broken**, it was introduced in #9970
You can reproduce with code below:
```java
class Scratch {
private static final Logger LOG = LoggerFactory.getLogger(Scratch.class);
public static void main(String[] args) throws Exception {
PulsarClient pulsarClient = PulsarClient.builder()
.serviceUrl(args[0])
.build();
DeadLetterPolicy deadLetterPolicy = DeadLetterPolicy.builder()
.maxRedeliverCount(0)
.build();
Consumer<byte[]> consumer = pulsarClient.newConsumer()
.topic(args[1])
.subscriptionName("consumeTest")
.subscriptionType(SubscriptionType.Shared)
.deadLetterPolicy(deadLetterPolicy)
.ackTimeout(10, TimeUnit.SECONDS)
.subscribe();
int i = 1;
Message<byte[]> message;
while ((message = consumer.receive()) != null) {
MessageId messageId = message.getMessageId();
LOG.info("Receive a message {}: {}", messageId, new
String(message.getData()));
if (i-- > 0) {
LOG.info("Skip a message {}", messageId);
continue;
}
consumer.acknowledge(messageId);
}
new CountDownLatch(1).await();
}
}
```
It will log exception below:
```
Dead letter producer exception with topic: {{topic}}
java.util.concurrent.CompletionException: java.lang.NullPointerException
at
java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:273)
at
java.util.concurrent.CompletableFuture.completeThrowable(CompletableFuture.java:280)
at
java.util.concurrent.CompletableFuture.uniAccept(CompletableFuture.java:659)
at
java.util.concurrent.CompletableFuture$UniAccept.tryFire(CompletableFuture.java:632)
at
java.util.concurrent.CompletableFuture$Completion.exec(CompletableFuture.java:443)
at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289)
at
java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056)
at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1692)
at
java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157)
Caused by: java.lang.NullPointerException
at java.util.Objects.requireNonNull(Objects.java:203)
at
org.apache.pulsar.client.impl.schema.AbstractSchema.atSchemaVersion(AbstractSchema.java:81)
at
org.apache.pulsar.client.impl.MessageImpl.getReaderSchema(MessageImpl.java:398)
at
org.apache.pulsar.client.impl.ConsumerImpl.lambda$processPossibleToDLQ$38(ConsumerImpl.java:1692)
at
java.util.concurrent.CompletableFuture.uniAccept(CompletableFuture.java:656)
... 6 more
```
```java
// MessageImpl#getReaderSchema
public Optional<Schema<?>> getReaderSchema() {
ensureSchemaIsLoaded();
if (schema == null) {
return Optional.empty();
}
if (schema instanceof AutoConsumeSchema) {
byte[] schemaVersion = getSchemaVersion();
return Optional.of(((AutoConsumeSchema) schema)
.atSchemaVersion(schemaVersion));
} else if (schema instanceof AbstractSchema) {
byte[] schemaVersion = getSchemaVersion(); // schemaVersion
may be null, e.g. BYTES schema
return Optional.of(((AbstractSchema<?>) schema)
.atSchemaVersion(schemaVersion)); // if
schemaVersion is null, a NPE will throw
} else {
return Optional.of(schema);
}
}
```
### Modifications
Make `AbstractSchema#atSchemaVersion` throw NPE only if
`supportSchemaVersioning` is true and schemaVersion is null.
### Verifying this change
This change added tests and can be verified as follows:
- *Added a unit test for MessageImpl#getReaderSchema with a message which
has BYTES schema*
### Does this pull request potentially affect one of the following parts:
*If `yes` was chosen, please highlight the changes*
- Dependencies (does it add or upgrade a dependency): (no)
- The public API: (no)
- The schema: (no)
- The default values of configurations: (no)
- The wire protocol: (no)
- The rest endpoints: (no)
- The admin cli options: (no)
- Anything that affects deployment: (no)
### Documentation
Check the box below or label this PR directly (if you have committer
privilege).
Need to update docs?
- [ ] `doc-required`
(If you need help on updating docs, create a doc issue)
- [x] `no-need-doc`
Bugfix only
- [ ] `doc`
(If this PR contains doc changes)
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