yuzhou created KAFKA-21285:
------------------------------
Summary: Dynamic configs less than half the value in
server.properties will not take effect after restart in kraft mode
Key: KAFKA-21285
URL: https://issues.apache.org/jira/browse/KAFKA-21285
Project: Kafka
Issue Type: Bug
Components: config
Affects Versions: 4.3.1
Reporter: yuzhou
Dynamic configs less than half the value in server.properties will not take
effect after restart in kraft mode
first, start kafka kraft mode, in server.properties, add "num.io.threads=16"
then, modify config from 16 to 8 then to 6
bin/kafka-configs.sh --bootstrap-server localhost:9092 --entity-type brokers
--entity-default --alter --add-config num.io.threads=8
bin/kafka-configs.sh --bootstrap-server localhost:9092 --entity-type brokers
--entity-default --alter --add-config num.io.threads=6
finally, restart broker.
after restart, log show:
[2026-10-15 15:45:10,838] INFO [DynamicConfigPublisher controller id=1]
Updating cluster configuration : num.io.threads -> 6,min.insync.replicas -> 1
(kafka.server.metadata.DynamicConfigPublisher)
...
[2026-10-15 15:45:11,274] ERROR Failed to update broker configuration with
configs :
{advertised.listeners=PLAINTEXT://localhost:9092,CONTROLLER://localhost:9093,
broker.id=1, controller.listener.names=CONTROLLER,
controller.quorum.bootstrap.servers=localhost:9093,
inter.broker.listener.name="PLAINTEXT",
listener.security.protocol.map="CONTROLLER:PLAINTEXT,PLAINTEXT:PLAINTEXT,SSL:SSL,SASL_PLAINTEXT:SASL_PLAINTEXT,SASL_SSL:SASL_SSL",
listeners=PLAINTEXT://:9092,CONTROLLER://:9093,
log.dirs=/tmp/kraft-combined-logs, log.retention.check.interval.ms=300000,
log.retention.hours=168, log.segment.bytes=1073741824, min.insync.replicas=1,
node.id=1, num.io.threads=6, num.network.threads=3, num.partitions=1,
num.recovery.threads.per.data.dir=2, offsets.topic.replication.factor=1,
process.roles=broker,controller, share.coordinator.state.topic.min.isr=1,
share.coordinator.state.topic.replication.factor=1,
socket.receive.buffer.bytes=102400, socket.request.max.bytes=104857600,
socket.send.buffer.bytes=102400, transaction.state.log.min.isr=1,
transaction.state.log.replication.factor=1} (kafka.server.DynamicBrokerConfig)
org.apache.kafka.common.config.ConfigException: Dynamic thread count update
validation failed for num.io.threads=6, value should be at least half the
current value 16
at
org.apache.kafka.server.DynamicThreadPool.validateReconfiguration(DynamicThreadPool.java:51)
at
kafka.server.BrokerDynamicThreadPool.validateReconfiguration(DynamicBrokerConfig.scala:647)
at
kafka.server.DynamicBrokerConfig.$anonfun$processReconfiguration$3(DynamicBrokerConfig.scala:466)
at
java.base/java.util.concurrent.CopyOnWriteArrayList.forEach(CopyOnWriteArrayList.java:807)
at
kafka.server.DynamicBrokerConfig.processReconfiguration(DynamicBrokerConfig.scala:464)
at
kafka.server.DynamicBrokerConfig.updateCurrentConfig(DynamicBrokerConfig.scala:437)
at
kafka.server.DynamicBrokerConfig.$anonfun$updateDefaultConfig$1(DynamicBrokerConfig.scala:293)
at org.apache.kafka.server.util.LockUtils.inLock(LockUtils.java:96)
at
org.apache.kafka.server.util.LockUtils.inWriteLock(LockUtils.java:115)
at
kafka.server.DynamicBrokerConfig.updateDefaultConfig(DynamicBrokerConfig.scala:288)
at
kafka.server.BrokerConfigHandler.processConfigChanges(ConfigHandler.scala:150)
at
kafka.server.metadata.DynamicConfigPublisher.$anonfun$onMetadataUpdate$5(DynamicConfigPublisher.scala:81)
at scala.Option.foreach(Option.scala:437)
at
kafka.server.metadata.DynamicConfigPublisher.$anonfun$onMetadataUpdate$2(DynamicConfigPublisher.scala:74)
at java.base/java.util.HashMap$KeySet.forEach(HashMap.java:1008)
at
kafka.server.metadata.DynamicConfigPublisher.$anonfun$onMetadataUpdate$1(DynamicConfigPublisher.scala:57)
at
kafka.server.metadata.DynamicConfigPublisher.$anonfun$onMetadataUpdate$1$adapted(DynamicConfigPublisher.scala:56)
at scala.Option.foreach(Option.scala:437)
at
kafka.server.metadata.DynamicConfigPublisher.onMetadataUpdate(DynamicConfigPublisher.scala:56)
at
kafka.server.metadata.BrokerMetadataPublisher.onMetadataUpdate(BrokerMetadataPublisher.scala:190)
at
org.apache.kafka.image.loader.MetadataLoader.initializeNewPublishers(MetadataLoader.java:332)
at
org.apache.kafka.image.loader.MetadataLoader.lambda$scheduleInitializeNewPublishers$0(MetadataLoader.java:288)
at
org.apache.kafka.queue.KafkaEventQueue$EventContext.run(KafkaEventQueue.java:134)
at
org.apache.kafka.queue.KafkaEventQueue$EventHandler.handleEvents(KafkaEventQueue.java:217)
at
org.apache.kafka.queue.KafkaEventQueue$EventHandler.run(KafkaEventQueue.java:188)
at java.base/java.lang.Thread.run(Thread.java:840)
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
