Karaf - Kafka OSGI bundle - Producer issue

Question

I am trying to create a simple bundle for Kafka producer in apache Karaf version 4.0.3 .

Here is my Java code

Properties props = new Properties();
props.put("bootstrap.servers", "localhost:9092");
props.put("acks", "all");
props.put("retries", 0);
props.put("batch.size", 16384);
props.put("linger.ms", 1);
props.put("buffer.memory", 33554432);
//props.put("key.serializer", "org.apache.kafka.common.serialization.StringSerializer");
//props.put("value.serializer", "org.apache.kafka.common.serialization.StringSerializer");
props.put("partitioner.class","org.apache.kafka.clients.producer.internals.DefaultPartitioner");
Producer<String, String> producer = new KafkaProducer<String,String>(props,new StringSerializer(),new StringSerializer());
//for(int i = 0; i < 100; i++)
    producer.send(new ProducerRecord<String, String>("test","data", outputData));

producer.close();

I have clearly declared the respective dependency in pom.xml

<dependency>
        <groupId>org.apache.servicemix.bundles</groupId>
        <artifactId>org.apache.servicemix.bundles.kafka-clients</artifactId>
        <version>0.9.0.0_1</version>
</dependency>

I have deployed that kafka client bundle too.

but on starting the producer i see below exception on first Attempt .

Exception in thread "pool-135-thread-1" java.lang.ExceptionInInitializerError
    at org.apache.kafka.clients.producer.KafkaProducer.<init>(KafkaProducer.java:194)
    .
    .
    .
    at com.google.common.util.concurrent.Futures$6.run(Futures.java:1319)
    at com.gilt.gfc.guava.future.FutureConverters$ScalaFutureAdapter$$anonfun$addListener$1.apply(FutureConverters.scala:72)
    at com.gilt.gfc.guava.future.FutureConverters$ScalaFutureAdapter$$anonfun$addListener$1.apply(FutureConverters.scala:72)
    at scala.concurrent.impl.CallbackRunnable.run(Promise.scala:32)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)
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)
    ... 12 more

And then consecutively this one ...

Exception in thread "pool-136-thread-1" java.lang.NoClassDefFoundError: Could not initialize class org.apache.kafka.clients.producer.ProducerConfig
at org.apache.kafka.clients.producer.KafkaProducer.<init>(KafkaProducer.java:194)
.
.
.
at com.google.common.util.concurrent.Futures$6.run(Futures.java:1319)
at com.gilt.gfc.guava.future.FutureConverters$ScalaFutureAdapter$$anonfun$addListener$1.apply(FutureConverters.scala:72)
at com.gilt.gfc.guava.future.FutureConverters$ScalaFutureAdapter$$anonfun$addListener$1.apply(FutureConverters.scala:72)
at scala.concurrent.impl.CallbackRunnable.run(Promise.scala:32)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745

Has anyone encoutered similar issue with the bundle ??

Answer 1

I saw this same problem in 0.9.0. It turned out that a Thread context loader was set, and in that case Kafka uses that classloader to resolve. So the thread context classloader should either be:

• A classloader that can resolve all the Kafka related stuff
• null

Don't know if this is going to bite me, but adding:

Thread.currentThread().setContextClassLoader(null);

did the trick.

Answer 2

using Kafka client version 0.8.2.2_1, solved the issue .

Answer 3

Might me useful for others, work around suggested in JIRA

props.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, org.apache.kafka.common.serialization.StringSerializer.class);

props.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, org.apache.kafka.common.serialization.StringSerializer.class);