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David Arthur commented on KAFKA-690: ------------------------------------ Removing the debug statement fixes the issue. However, it seems instead of returning all of the topic metadata - I get none. Here are some trace logs when I send a TopicMetadataRequest with no topics [2013-01-08 19:53:34,463] TRACE 26 bytes read from /127.0.0.1:61558 (kafka.network.Processor) [2013-01-08 19:53:34,465] TRACE Received request: TopicMetadataRequest(0,kafka-python,List(),0) (kafka.network.RequestChannel$) [2013-01-08 19:53:34,466] TRACE Recieved request, sending for processing by handler: Request(1,sun.nio.ch.SelectionKeyImpl@785e8d7d,java.nio.HeapByteBuffer[pos=0 lim=26 cap=26],1357692814463) (kafka.network.Processor) [2013-01-08 19:53:34,466] DEBUG [Kafka Request Handler 1 on Broker 0], handles request Request(1,sun.nio.ch.SelectionKeyImpl@785e8d7d,java.nio.HeapByteBuffer[pos=0 lim=26 cap=26],1357692814463) (kafka.server.KafkaRequestHandler) [2013-01-08 19:53:34,466] TRACE Handling topic metadata request TopicMetadataRequest(0,kafka-python,List(),0) (kafka.request.logger) [2013-01-08 19:53:34,466] TRACE [KafkaApi-0] Handling topic metadata request TopicMetadataRequest(0,kafka-python,List(),0) (kafka.server.KafkaApis) [2013-01-08 19:53:34,475] TRACE Socket server received response to send, registering for write: Response(1,Request(1,sun.nio.ch.SelectionKeyImpl@785e8d7d,java.nio.HeapByteBuffer[pos=0 lim=26 cap=26],1357692814463),kafka.network.BoundedByteBufferSend@2e82674b) (kafka.network.Processor) [2013-01-08 19:53:34,476] TRACE 16 bytes written to /127.0.0.1:61558 (kafka.network.Processor) [2013-01-08 19:53:34,476] TRACE Completed request: TopicMetadataRequest(0,kafka-python,List(),0) totalTime:13 queueTime:3 localTime:9 remoteTime:0 sendTime:1 (kafka.network.RequestChannel$) I would expect this to return info about the one existing topic "test". Here are the logs for when I send a TopicMetadataRequest with the "test" topic (this gives the expected response): [2013-01-08 19:55:26,247] TRACE 32 bytes read from /127.0.0.1:61719 (kafka.network.Processor) [2013-01-08 19:55:26,247] TRACE Received request: TopicMetadataRequest(0,kafka-python,List(test),0) (kafka.network.RequestChannel$) [2013-01-08 19:55:26,247] TRACE Recieved request, sending for processing by handler: Request(0,sun.nio.ch.SelectionKeyImpl@30d647d8,java.nio.HeapByteBuffer[pos=0 lim=32 cap=32],1357692926247) (kafka.network.Processor) [2013-01-08 19:55:26,247] DEBUG [Kafka Request Handler 0 on Broker 0], handles request Request(0,sun.nio.ch.SelectionKeyImpl@30d647d8,java.nio.HeapByteBuffer[pos=0 lim=32 cap=32],1357692926247) (kafka.server.KafkaRequestHandler) [2013-01-08 19:55:26,247] TRACE Handling topic metadata request TopicMetadataRequest(0,kafka-python,List(test),0) (kafka.request.logger) [2013-01-08 19:55:26,247] TRACE [KafkaApi-0] Handling topic metadata request TopicMetadataRequest(0,kafka-python,List(test),0) (kafka.server.KafkaApis) [2013-01-08 19:55:26,248] DEBUG Reading reply sessionid:0x13c15a1d848003f, packet:: clientPath:null serverPath:null finished:false header:: 30,3 replyHeader:: 30,354,0 request:: '/kafka/brokers/topics/test,F response:: s{320,320,1357689749289,1357689749289,0,1,0,0,14,1,323} (org.apache.zookeeper.ClientCnxn) [2013-01-08 19:55:26,249] DEBUG Reading reply sessionid:0x13c15a1d848003f, packet:: clientPath:null serverPath:null finished:false header:: 31,4 replyHeader:: 31,354,0 request:: '/kafka/brokers/topics/test,F response:: #7b202230223a205b2230225d207d,s{320,320,1357689749289,1357689749289,0,1,0,0,14,1,323} (org.apache.zookeeper.ClientCnxn) [2013-01-08 19:55:26,252] DEBUG Partition map for /brokers/topics/test is Map(0 -> List(0)) (kafka.utils.ZkUtils$) [2013-01-08 19:55:26,255] DEBUG Reading reply sessionid:0x13c15a1d848003f, packet:: clientPath:null serverPath:null finished:false header:: 32,4 replyHeader:: 32,354,0 request:: '/kafka/brokers/topics/test/partitions/0/leaderAndISR,F response:: #7b2022495352223a2230222c226c6561646572223a2230222c22636f6e74726f6c6c657245706f6368223a2232222c226c656164657245706f6368223a223022207d,s{325,325,1357689749406,1357689749406,0,0,0,0,66,0,325} (org.apache.zookeeper.ClientCnxn) [2013-01-08 19:55:26,266] DEBUG Reading reply sessionid:0x13c15a1d848003f, packet:: clientPath:null serverPath:null finished:false header:: 33,4 replyHeader:: 33,354,0 request:: '/kafka/brokers/topics/test/partitions/0/leaderAndISR,F response:: #7b2022495352223a2230222c226c6561646572223a2230222c22636f6e74726f6c6c657245706f6368223a2232222c226c656164657245706f6368223a223022207d,s{325,325,1357689749406,1357689749406,0,0,0,0,66,0,325} (org.apache.zookeeper.ClientCnxn) [2013-01-08 19:55:26,277] DEBUG replicas = List(0), in sync replicas = ArrayBuffer(0), leader = Some(0) (kafka.admin.AdminUtils$) [2013-01-08 19:55:26,278] DEBUG Reading reply sessionid:0x13c15a1d848003f, packet:: clientPath:null serverPath:null finished:false header:: 34,4 replyHeader:: 34,354,0 request:: '/kafka/brokers/ids/0,F response:: #3139322e3136382e322e313a393039323a39393939,s{352,352,1357692804787,1357692804787,0,0,0,88969877503082559,21,0,352} (org.apache.zookeeper.ClientCnxn) >>> The TopicMetadataResponse <<< [2013-01-08 19:55:26,282] TRACE [KafkaApi-0] Sending topic metadata TopicMetadata(test,List(PartitionMetadata(0,Some(id:0,host:192.168.2.1,port:9092),List(id:0,host:192.168.2.1,port:9092),ArrayBuffer(id:0,host:192.168.2.1,port:9092),0)),0) (kafka.server.KafkaApis) [2013-01-08 19:55:26,284] TRACE Socket server received response to send, registering for write: Response(0,Request(0,sun.nio.ch.SelectionKeyImpl@30d647d8,java.nio.HeapByteBuffer[pos=0 lim=32 cap=32],1357692926247),kafka.network.BoundedByteBufferSend@3ddfd90f) (kafka.network.Processor) [2013-01-08 19:55:26,284] TRACE 75 bytes written to /127.0.0.1:61719 (kafka.network.Processor) [2013-01-08 19:55:26,284] TRACE Completed request: TopicMetadataRequest(0,kafka-python,List(test),0) totalTime:37 queueTime:0 localTime:37 remoteTime:0 sendTime:0 (kafka.network.RequestChannel$) [2013-01-08 19:55:26,285] INFO Closing socket connection to /127.0.0.1. (kafka.network.Processor) [2013-01-08 19:55:26,285] DEBUG Closing connection from /127.0.0.1:61719 (kafka.network.Processor) > TopicMetadataRequest throws exception when no topics are specified > ------------------------------------------------------------------ > > Key: KAFKA-690 > URL: https://issues.apache.org/jira/browse/KAFKA-690 > Project: Kafka > Issue Type: Bug > Components: core > Affects Versions: 0.8 > Reporter: David Arthur > Fix For: 0.8 > > > If no topics are sent in a TopicMetadataRequest, `readFrom` throws an > exception when trying to get the the head of the topic list for a debug > statement. > java.util.NoSuchElementException: head of empty list > at scala.collection.immutable.Nil$.head(List.scala:386) > at scala.collection.immutable.Nil$.head(List.scala:383) > at > kafka.api.TopicMetadataRequest$$anonfun$readFrom$2.apply(TopicMetadataRequest.scala:43) > at > kafka.api.TopicMetadataRequest$$anonfun$readFrom$2.apply(TopicMetadataRequest.scala:43) > at kafka.utils.Logging$class.debug(Logging.scala:51) > at kafka.api.TopicMetadataRequest$.debug(TopicMetadataRequest.scala:25) > at > kafka.api.TopicMetadataRequest$.readFrom(TopicMetadataRequest.scala:43) > at kafka.api.RequestKeys$$anonfun$4.apply(RequestKeys.scala:37) > at kafka.api.RequestKeys$$anonfun$4.apply(RequestKeys.scala:37) > at kafka.network.RequestChannel$Request.<init>(RequestChannel.scala:47) > at kafka.network.Processor.read(SocketServer.scala:320) > at kafka.network.Processor.run(SocketServer.scala:231) > at java.lang.Thread.run(Thread.java:680) -- This message is automatically generated by JIRA. 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