Does kafka connect restart failed task - apache-kafka

Question

We have a source connector that reads from rdbms and put to kafka. It uses schema registry with avro schema.
I am finding following exceptions in kafka connect log and schema registry log respectively.
1.
Committing offsets (org.apache.kafka.connect.runtime.WorkerSourceTask:426)
WorkerSourceTask{id=A-0} flushing 0 outstanding messages for offset commit (org.apache.kafka.connect.runtime.WorkerSourceTask:443)
Task threw an uncaught and unrecoverable exception (org.apache.kafka.connect.runtime.WorkerTask:186)
org.apache.kafka.connect.errors.ConnectException: Tolerance exceeded in error handler
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Caused by: org.apache.kafka.connect.errors.DataException: Failed to serialize Avro data from topic A :
at io.confluent.connect.avro.AvroConverter.fromConnectData(AvroConverter.java:91)
at org.apache.kafka.connect.storage.Converter.fromConnectData(Converter.java:63)
.
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Caused by: org.apache.kafka.common.errors.SerializationException: Error registering Avro schema:
.
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Caused by: io.confluent.kafka.schemaregistry.client.rest.exceptions.RestClientException: Register operation timed out; error code: 50002
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Task is being killed and will not recover until manually restarted (org.apache.kafka.connect.runtime.WorkerTask:187)
Stopping JDBC source task (io.confluent.connect.jdbc.source.JdbcSourceTask:314)
Closing the Kafka producer with timeoutMillis = 30000 ms.
(org.apache.kafka.clients.producer.KafkaProducer:1182)
2.
Wait to catch up until the offset at 1 (io.confluent.kafka.schemaregistry.storage.KafkaStore:304)
Request Failed with exception (io.confluent.rest.exceptions.DebuggableExceptionMapper:62)
io.confluent.kafka.schemaregistry.rest.exceptions.RestSchemaRegistryTimeoutException: Register operation timed out
at io.confluent.kafka.schemaregistry.rest.exceptions.Errors.operationTimeoutException(Errors.java:132)
.
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Caused by: io.confluent.kafka.schemaregistry.exceptions.SchemaRegistryTimeoutException: Write to the Kafka store timed out while
at io.confluent.kafka.schemaregistry.storage.KafkaSchemaRegistry.register(KafkaSchemaRegistry.java:508)
at io.confluent.kafka.schemaregistry.storage.KafkaSchemaRegistry.registerOrForward(KafkaSchemaRegistry.java:553)
.
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Caused by: io.confluent.kafka.schemaregistry.storage.exceptions.StoreTimeoutException: KafkaStoreReaderThread failed to reach target offset within the timeout interval. targetOffset: 3, offsetReached: 1, timeout(ms): 50
0
So basically schema registry before registering schema moves offset to latest and there it time out 500ms.
My question was this.
How can I find why it is not able to read from kafka?
Does the source connector task restart or poll data for the failed task of one connector? Because in later section of the log I see this.
Committing offsets (org.apache.kafka.connect.runtime.WorkerSourceTask:426)
WorkerSourceTask{id=A-0} flushing 0 outstanding messages for offset commit (org.apache.kafka.connect.runtime.WorkerSourceTask:443)
So eariler it failed after this, but now it is not printing it, which means it passed.
The key thing to note is that when it failed eariler reading, it failed task for only one connector A and others passed. Later I didn't find the exception for the connector A.
If the task is not starting or connector is not polling again, I need to restart task using rest API.
Any help will be greatly appriciated.
Thanks in advance.

Answer 1

Regarding your question title, read the error.
task will not recover until manually restarted
If you have more than one task, you would still expect to see logs from other tasks.
As far as offset commits, source task offsets would not be committed until the task succeeds, and no logs given show something "moving to latest"
The error has nothing to do with reading from Kafka. The error is a timeout in your schema registry client in the AvroConverter, which isn't required for Kafka Connect.