I followed linkedin setup example in the docs and located 3g for heap size.
java -Xmx3G -Xms3G -server -XX:+UseCompressedOops -XX:+UseParNewGC -XX:+UseConcMarkSweepGC -XX:+CMSClassUnloadingEnabled -XX:+CMSScavengeBeforeRemark -XX:+DisableExplicitGC - After a day of normal run scenario I discovered the following errors flooding the error log. I can increase the heap size its not a problem, but I want to be able properly estimate how much memory kafka will use in order to predict system limits as we add topics, consumers and etc. Thanks so much in advance, Vadim [2013-08-29 23:57:14,072] ERROR [ReplicaFetcherThread--1-6], Error due to (kafka.server.ReplicaFetcherThread) java.lang.OutOfMemoryError: Java heap space at sun.nio.cs.StreamEncoder.write(StreamEncoder.java:114) at java.io.OutputStreamWriter.write(OutputStreamWriter.java:203) at java.io.Writer.write(Writer.java:140) at org.apache.log4j.helpers.QuietWriter.write(QuietWriter.java:48) at org.apache.log4j.WriterAppender.subAppend(WriterAppender.java:302) at com.ordersets.utils.logging.CustodianDailyRollingFileAppender.subAppend(CustodianDailyRollingFileAppender.java:299) at org.apache.log4j.WriterAppender.append(WriterAppender.java:160) at org.apache.log4j.AppenderSkeleton.doAppend(AppenderSkeleton.java:251) at org.apache.log4j.helpers.AppenderAttachableImpl.appendLoopOnAppenders(AppenderAttachableImpl.java:66) at org.apache.log4j.Category.callAppenders(Category.java:206) at org.apache.log4j.Category.forcedLog(Category.java:391) at org.apache.log4j.Category.warn(Category.java:1060) at kafka.utils.Logging$class.warn(Logging.scala:88) at kafka.utils.ShutdownableThread.warn(ShutdownableThread.scala:23) at kafka.server.AbstractFetcherThread.processFetchRequest(AbstractFetcherThread.scala:100) at kafka.server.AbstractFetcherThread.doWork(AbstractFetcherThread.scala:88) at kafka.utils.ShutdownableThread.run(ShutdownableThread.scala:51) [2013-08-30 10:21:44,932] ERROR [Kafka Request Handler 4 on Broker 5], Exception when handling request (kafka.server.KafkaRequestHandler) java.lang.NullPointerException at kafka.api.FetchResponsePartitionData.<init>(FetchResponse.scala:46) at kafka.api.FetchRequest$$anonfun$2.apply(FetchRequest.scala:158) at kafka.api.FetchRequest$$anonfun$2.apply(FetchRequest.scala:156) at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:233) at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:233) at scala.collection.immutable.HashMap$HashMap1.foreach(HashMap.scala:178) at scala.collection.immutable.HashMap$HashTrieMap.foreach(HashMap.scala:347) at scala.collection.immutable.HashMap$HashTrieMap.foreach(HashMap.scala:347) at scala.collection.TraversableLike$class.map(TraversableLike.scala:233) at scala.collection.immutable.HashMap.map(HashMap.scala:38) at kafka.api.FetchRequest.handleError(FetchRequest.scala:156) at kafka.server.KafkaApis.handle(KafkaApis.scala:78) at kafka.server.KafkaRequestHandler.run(KafkaRequestHandler.scala:42) at java.lang.Thread.run(Thread.java:662) [2013-08-30 10:05:17,214] ERROR [Kafka Request Handler 6 on Broker 5], Exception when handling request (kafka.server.KafkaRequestHandler) java.lang.NullPointerException at kafka.api.FetchResponsePartitionData.<init>(FetchResponse.scala:46) at kafka.api.FetchRequest$$anonfun$2.apply(FetchRequest.scala:158) at kafka.api.FetchRequest$$anonfun$2.apply(FetchRequest.scala:156) at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:233) at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:233) at scala.collection.immutable.HashMap$HashMap1.foreach(HashMap.scala:178) at scala.collection.immutable.HashMap$HashTrieMap.foreach(HashMap.scala:347) at scala.collection.immutable.HashMap$HashTrieMap.foreach(HashMap.scala:347) at scala.collection.TraversableLike$class.map(TraversableLike.scala:233) at scala.collection.immutable.HashMap.map(HashMap.scala:38) at kafka.api.FetchRequest.handleError(FetchRequest.scala:156) at kafka.server.KafkaApis.handle(KafkaApis.scala:78) at kafka.server.KafkaRequestHandler.run(KafkaRequestHandler.scala:42) at java.lang.Thread.run(Thread.java:662) [2013-08-30 10:06:55,929] INFO Closing socket connection to /10.15.11.19. (kafka.network.Processor)