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[improve][broker] log incompatible schema failures at warn level, rather than logging at error level - #26804

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[improve][broker] log incompatible schema failures at warn level, rather than logging at error level#26804
poorbarcode wants to merge 1 commit into
apache:masterfrom
poorbarcode:improve/log_put_incompatable_schema

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@poorbarcode

@poorbarcode poorbarcode commented Oct 1, 2026 •
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Motivation

Schema compatibility validation failures can be wrapped in CompletionException. The schema registry previously checked only the outer exception type, causing expected incompatible-schema failures to be logged as errors. Unwrapping the completion exception allows these expected validation failures to be logged at WARN level while preserving ERROR logging for unexpected failures.

You can reproduce it by the test SchemaServiceTest.checkIsCompatible -> case 3 -> assertThatThrownBy(() -> putSchema(...)

2026-10-01T13:25:26,800+0000 [BookKeeperClientWorker-OrderedExecutor-1-0] WARN  org.apache.pulsar.broker.service.schema.SchemaRegistryServiceImpl - [public/default/tp] Schema is incompatible
2026-10-01T13:25:26,801+0000 [BookKeeperClientWorker-OrderedExecutor-1-0] ERROR org.apache.pulsar.broker.service.schema.SchemaRegistryServiceImpl - [public/default/tp] Put schema failed
java.util.concurrent.CompletionException: org.apache.pulsar.broker.service.schema.exceptions.IncompatibleSchemaException: Error during schema compatibility check with strategy FULL: org.apache.avro.SchemaValidationException: Unable to read schema: 
{...}
	at java.base/java.util.concurrent.CompletableFuture.encodeRelay(Unknown Source)
	at java.base/java.util.concurrent.CompletableFuture.completeRelay(Unknown Source)
	at java.base/java.util.concurrent.CompletableFuture$UniCompose.tryFire(Unknown Source)
	at java.base/java.util.concurrent.CompletableFuture.postComplete(Unknown Source)
	at java.base/java.util.concurrent.CompletableFuture.complete(Unknown Source)
	at org.apache.pulsar.broker.service.schema.BookkeeperSchemaStorage$Functions.lambda$getLedgerEntry$0(BookkeeperSchemaStorage.java:711)
	at org.apache.bookkeeper.client.LedgerHandle$6.onSuccess(LedgerHandle.java:1050)
	at org.apache.bookkeeper.client.LedgerHandle$6.onSuccess(LedgerHandle.java:1047)
	at org.apache.bookkeeper.common.concurrent.FutureEventListener.accept(FutureEventListener.java:42)
	at org.apache.bookkeeper.common.concurrent.FutureEventListener.accept(FutureEventListener.java:26)
	at java.base/java.util.concurrent.CompletableFuture.uniWhenComplete(Unknown Source)
	at java.base/java.util.concurrent.CompletableFuture$UniWhenComplete.tryFire(Unknown Source)
	at java.base/java.util.concurrent.CompletableFuture$Completion.run(Unknown Source)
	at org.apache.bookkeeper.common.util.SingleThreadExecutor.safeRunTask(SingleThreadExecutor.java:128)
	at org.apache.bookkeeper.common.util.SingleThreadExecutor.run(SingleThreadExecutor.java:99)
	at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
	at java.base/java.lang.Thread.run(Unknown Source)
Caused by: org.apache.pulsar.broker.service.schema.exceptions.IncompatibleSchemaException: Error during schema compatibility check with strategy FULL: org.apache.avro.SchemaValidationException
...
...

Modifications

Correct log level. Since it is a log level change, it is hard to add a verification for it, I did not modify the test

Does this pull request potentially affect one of the following parts:

If the box was checked, please highlight the changes

  • Dependencies (add or upgrade a dependency)
  • The public API
  • The schema
  • The default values of configurations
  • The threading model
  • The binary protocol
  • The REST endpoints
  • The admin CLI options
  • The metrics
  • Anything that affects deployment

@poorbarcode poorbarcode added this to the 5.0.0 milestone Oct 1, 2026
@poorbarcode poorbarcode self-assigned this Oct 1, 2026
@poorbarcode poorbarcode changed the title [improve][log] log incompatible schema failures at warn level, rather… [improve][broker] log incompatible schema failures at warn level, rather… Oct 1, 2026
@poorbarcode poorbarcode changed the title [improve][broker] log incompatible schema failures at warn level, rather… [improve][broker] log incompatible schema failures at warn level, rather than logging at error level Oct 1, 2026
merlimat
merlimat reviewed Oct 1, 2026
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Comment thread ...-broker/src/main/java/org/apache/pulsar/broker/service/schema/SchemaRegistryServiceImpl.java
var latencyMs = this.clock.millis() - start.longValue();
if (ex != null) {
if (ex instanceof IncompatibleSchemaException) {
if (actEx instanceof IncompatibleSchemaException) {

@merlimat merlimat Oct 1, 2026 •
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@poorbarcode We could also use exceptionMessage() instead of exception() cause we don't need the full stacktrace. And log actEx instead of ex

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@merlimat merlimat merlimat left review comments
@gaoran10 gaoran10 gaoran10 approved these changes

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