[infinispan-issues] [JBoss JIRA] (ISPN-2781) NPE in AbstractTopologyAwareEncoder1x

[Dan Berindei (JIRA)]

    [ https://issues.jboss.org/browse/ISPN-2781?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12754413#comment-12754413 ] 

Dan Berindei commented on ISPN-2781:
------------------------------------

Galderz, yes, this is again a problem with the topology cache being modified while we are writing a topology response to the client.

Earlier versions of the code had the same problem - we don't hold any lock while generating the client response, so anyone can modify the topology cache while we are generating the response, and this was always the case. Note that a new client will always require a topology response, regardless of when the topology has last changed.

At one point I did add an extra check to skip a node's hash from the topology response if it wasn't in the topology cache any more, but I thought (wrongly) that the extra membership check that you pointed out made it impossible and I deleted it.

I'm going to take a snapshot of the topology cache before generating the response and I'm going to use that copy for everything. Topology changes are very rare anyway, so it shouldn't make a difference performance-wise, and it will make the code easier to reason about.
                
> NPE in AbstractTopologyAwareEncoder1x
> -------------------------------------
>
>                 Key: ISPN-2781
>                 URL: https://issues.jboss.org/browse/ISPN-2781
>             Project: Infinispan
>          Issue Type: Bug
>          Components: Server
>    Affects Versions: 5.2.0.CR3
>            Reporter: Michal Linhard
>            Assignee: Dan Berindei
>             Fix For: 5.2.2.Final, 5.3.0.Final
>
>
> got this in an elasticity test (32nodes)
> {code}
> 06:23:20,660 ERROR [org.infinispan.server.hotrod.HotRodDecoder] (HotRodServerWorker-151) ISPN005009: Unexpected error before any request parameters read: java.lang.NullPointerException
> 	at org.infinispan.server.hotrod.AbstractTopologyAwareEncoder1x$$anonfun$writeHashTopologyUpdate11$3.apply(AbstractTopologyAwareEncoder1x.scala:102) [infinispan-server-hotrod-5.2.0.CR3-redhat-1.jar:5.2.0.CR3-redhat-1]
> 	at org.infinispan.server.hotrod.AbstractTopologyAwareEncoder1x$$anonfun$writeHashTopologyUpdate11$3.apply(AbstractTopologyAwareEncoder1x.scala:101) [infinispan-server-hotrod-5.2.0.CR3-redhat-1.jar:5.2.0.CR3-redhat-1]
> 	at scala.collection.mutable.ResizableArray$class.foreach(ResizableArray.scala:59)
> 	at scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:47)
> 	at org.infinispan.server.hotrod.AbstractTopologyAwareEncoder1x.writeHashTopologyUpdate11(AbstractTopologyAwareEncoder1x.scala:101) [infinispan-server-hotrod-5.2.0.CR3-redhat-1.jar:5.2.0.CR3-redhat-1]
> 	at org.infinispan.server.hotrod.AbstractTopologyAwareEncoder1x.writeHashTopologyUpdate(AbstractTopologyAwareEncoder1x.scala:52) [infinispan-server-hotrod-5.2.0.CR3-redhat-1.jar:5.2.0.CR3-redhat-1]
> 	at org.infinispan.server.hotrod.AbstractEncoder1x.writeHeader(AbstractEncoder1x.scala:63) [infinispan-server-hotrod-5.2.0.CR3-redhat-1.jar:5.2.0.CR3-redhat-1]
> 	at org.infinispan.server.hotrod.HotRodEncoder.encode(HotRodEncoder.scala:63) [infinispan-server-hotrod-5.2.0.CR3-redhat-1.jar:5.2.0.CR3-redhat-1]
> 	at org.jboss.netty.handler.codec.oneone.OneToOneEncoder.doEncode(OneToOneEncoder.java:66) [netty-3.6.1.Final.jar:]
> 	at org.jboss.netty.handler.codec.oneone.OneToOneEncoder.handleDownstream(OneToOneEncoder.java:59) [netty-3.6.1.Final.jar:]
> 	at org.jboss.netty.channel.Channels.write(Channels.java:704) [netty-3.6.1.Final.jar:]
> 	at org.jboss.netty.channel.Channels.write(Channels.java:671) [netty-3.6.1.Final.jar:]
> 	at org.jboss.netty.channel.AbstractChannel.write(AbstractChannel.java:248) [netty-3.6.1.Final.jar:]
> 	at org.infinispan.server.core.AbstractProtocolDecoder.writeResponse(AbstractProtocolDecoder.scala:179) [infinispan-server-core-5.2.0.CR3-redhat-1.jar:5.2.0.CR3-redhat-1]
> 	at org.infinispan.server.hotrod.HotRodDecoder.customDecodeHeader(HotRodDecoder.scala:157) [infinispan-server-hotrod-5.2.0.CR3-redhat-1.jar:5.2.0.CR3-redhat-1]
> 	at org.infinispan.server.core.AbstractProtocolDecoder.decodeHeader(AbstractProtocolDecoder.scala:105) [infinispan-server-core-5.2.0.CR3-redhat-1.jar:5.2.0.CR3-redhat-1]
> 	at org.infinispan.server.core.AbstractProtocolDecoder.decode(AbstractProtocolDecoder.scala:70) [infinispan-server-core-5.2.0.CR3-redhat-1.jar:5.2.0.CR3-redhat-1]
> 	at org.infinispan.server.core.AbstractProtocolDecoder.decode(AbstractProtocolDecoder.scala:47) [infinispan-server-core-5.2.0.CR3-redhat-1.jar:5.2.0.CR3-redhat-1]
> 	at org.jboss.netty.handler.codec.replay.ReplayingDecoder.callDecode(ReplayingDecoder.java:500) [netty-3.6.1.Final.jar:]
> 	at org.jboss.netty.handler.codec.replay.ReplayingDecoder.messageReceived(ReplayingDecoder.java:435) [netty-3.6.1.Final.jar:]
> 	at org.infinispan.server.core.AbstractProtocolDecoder.messageReceived(AbstractProtocolDecoder.scala:387) [infinispan-server-core-5.2.0.CR3-redhat-1.jar:5.2.0.CR3-redhat-1]
> 	at org.jboss.netty.channel.Channels.fireMessageReceived(Channels.java:268) [netty-3.6.1.Final.jar:]
> 	at org.jboss.netty.channel.Channels.fireMessageReceived(Channels.java:255) [netty-3.6.1.Final.jar:]
> 	at org.jboss.netty.channel.socket.nio.NioWorker.read(NioWorker.java:88) [netty-3.6.1.Final.jar:]
> 	at org.jboss.netty.channel.socket.nio.AbstractNioWorker.process(AbstractNioWorker.java:107) [netty-3.6.1.Final.jar:]
> 	at org.jboss.netty.channel.socket.nio.AbstractNioSelector.run(AbstractNioSelector.java:313) [netty-3.6.1.Final.jar:]
> 	at org.jboss.netty.channel.socket.nio.AbstractNioWorker.run(AbstractNioWorker.java:88) [netty-3.6.1.Final.jar:]
> 	at org.jboss.netty.channel.socket.nio.NioWorker.run(NioWorker.java:178) [netty-3.6.1.Final.jar:]
> 	at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) [rt.jar:1.6.0_33]
> 	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) [rt.jar:1.6.0_33]
> 	at java.lang.Thread.run(Thread.java:662) [rt.jar:1.6.0_33]
> {code}

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