[KAFKA-3218] Kafka-0.9.0.0 does not work as OSGi module

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.9.0.0
• Fix Version/s: 0.10.1.0
• Component/s: clients
• Environment: Apache Felix OSGi container; jdk_1.8.0_60
• Assignee: Rajini Sivaram
• Reporter: Joe O'Connor
• Created: 08/Feb/16 10:58
• Updated: 09/Nov/17 10:58
• Resolved: 23/Aug/16 12:02

Description

KAFKA-2295 changed all Class.forName() calls to use currentThread().getContextClassLoader() instead of the default "classloader that loaded the current class".

OSGi loads each module's classes using a separate classloader so this is now broken.

Steps to reproduce:

1. install the kafka-clients servicemix OSGi module 0.9.0.0_1
2. attempt to initialize the Kafka producer client from Java code

Expected results:

• call to "new KafkaProducer()" succeeds

Actual results:

• "new KafkaProducer()" throws ConfigException:

  Suppressed: java.lang.Exception: Error starting bundle54: Activator start error in bundle com.openet.testcase.ContextClassLoaderBug [54].
  at org.apache.karaf.bundle.command.BundlesCommand.doExecute(BundlesCommand.java:66)
  ... 12 more
  Caused by: org.osgi.framework.BundleException: Activator start error in bundle com.openet.testcase.ContextClassLoaderBug [54].
  at org.apache.felix.framework.Felix.activateBundle(Felix.java:2276)
  at org.apache.felix.framework.Felix.startBundle(Felix.java:2144)
  at org.apache.felix.framework.BundleImpl.start(BundleImpl.java:998)
  at org.apache.karaf.bundle.command.Start.executeOnBundle(Start.java:38)
  at org.apache.karaf.bundle.command.BundlesCommand.doExecute(BundlesCommand.java:64)
  ... 12 more
  Caused by: java.lang.ExceptionInInitializerError
  at org.apache.kafka.clients.producer.KafkaProducer.<init>(KafkaProducer.java:156)
  at com.openet.testcase.Activator.start(Activator.java:16)
  at org.apache.felix.framework.util.SecureAction.startActivator(SecureAction.java:697)
  at org.apache.felix.framework.Felix.activateBundle(Felix.java:2226)
  ... 16 more
  Caused by: org.apache.kafka.common.config.ConfigException: Invalid value org.apache.kafka.clients.producer.internals.DefaultPartitioner for configuration partitioner.class: Class org.apache.kafka.clients.producer.internals.DefaultPartitioner could not be found.
  at org.apache.kafka.common.config.ConfigDef.parseType(ConfigDef.java:255)
  at org.apache.kafka.common.config.ConfigDef.define(ConfigDef.java:78)
  at org.apache.kafka.common.config.ConfigDef.define(ConfigDef.java:94)
  at org.apache.kafka.clients.producer.ProducerConfig.<clinit>(ProducerConfig.java:206)

Workaround is to call "currentThread().setContextClassLoader(null)" before initializing the kafka producer.

Possible fix is to catch ClassNotFoundException at ConfigDef.java:247 and retry the Class.forName() call with the default classloader. However with this fix there is still a problem at AbstractConfig.java:206, where the newInstance() call succeeds but "instanceof" is false because the classes were loaded by different classloaders.

Testcase attached, see README.txt for instructions.

See also SM-2743

Issue Links

• relates to: KAFKA-2295 Dynamically loaded classes (encoders, etc.) may not be found by Kafka Producer
• relates to: SM-2743 Create OSGi bundles for Kafka 0.9.0.0
• links to: GitHub Pull Request #888