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From "Gareth Davis (JIRA)" <j...@apache.org>
Subject [jira] [Created] (AVRO-1407) NettyTransceiver can cause a infinite loop when slow to connect
Date Fri, 29 Nov 2013 11:01:36 GMT
Gareth Davis created AVRO-1407:
----------------------------------

             Summary: NettyTransceiver can cause a infinite loop when slow to connect
                 Key: AVRO-1407
                 URL: https://issues.apache.org/jira/browse/AVRO-1407
             Project: Avro
          Issue Type: Bug
          Components: java
    Affects Versions: 1.7.5, 1.7.6
            Reporter: Gareth Davis



When a new {{NettyTransceiver}} is created it forces the channel to be allocated and connected
to the remote host. it waits for the connectTimeout ms on the [connect channel future|https://github.com/apache/avro/blob/1579ab1ac95731630af58fc303a07c9bf28541d6/lang/java/ipc/src/main/java/org/apache/avro/ipc/NettyTransceiver.java#L271]
this is obivously a good thing it's only that on being unsuccessful, ie {{!channelFuture.isSuccess()}}
an exception is thrown and the call to the constructor fails with an {{IOException}}, but
has the potential to leave a active channel associated with the {{ChannelFactory}}

The problem is that a Netty {{NioClientSocketChannelFactory}} will not shutdown if there are
active channels still around and if you have supplied the {{ChannelFactory}} to the {{NettyTransceiver}}
then  you will not be able to cancel it by calling {{ChannelFactory.releaseExternalResources()}}
like the [Flume Avro RPC client does|https://github.com/apache/flume/blob/b8cf789b8509b1e5be05dd0b0b16c5d9af9698ae/flume-ng-sdk/src/main/java/org/apache/flume/api/NettyAvroRpcClient.java#L158].
In order to recreate this you need a very laggy network, where the connect attempt takes longer
than the connect timeout but does actually work, this very hard to organise in a test case,
although I do have a test setup using vagrant VM's that recreates this everytime, using the
Flume RPC client and server.

The following stack is from a production system, it won't ever leave recover until the channel
is disconnected (by forcing a disconnect at the remote host) or restarting the JVM.

{noformat:title=Production stack trace}
"TLOG-0" daemon prio=10 tid=0x00007f581c7be800 nid=0x39a1 waiting on condition [0x00007f57ef9f2000]
  java.lang.Thread.State: TIMED_WAITING (parking)
  at sun.misc.Unsafe.park(Native Method)
  parking to wait for <0x00000007218b16e0> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
  at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:196)
  at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awaitNanos(AbstractQueuedSynchronizer.java:2025)
  at java.util.concurrent.ThreadPoolExecutor.awaitTermination(ThreadPoolExecutor.java:1253)
  at org.jboss.netty.util.internal.ExecutorUtil.terminate(ExecutorUtil.java:103)
  at org.jboss.netty.channel.socket.nio.AbstractNioWorkerPool.releaseExternalResources(AbstractNioWorkerPool.java:80)
  at org.jboss.netty.channel.socket.nio.NioClientSocketChannelFactory.releaseExternalResources(NioClientSocketChannelFactory.java:181)
  at org.apache.flume.api.NettyAvroRpcClient.connect(NettyAvroRpcClient.java:142)
  at org.apache.flume.api.NettyAvroRpcClient.connect(NettyAvroRpcClient.java:101)
  at org.apache.flume.api.NettyAvroRpcClient.configure(NettyAvroRpcClient.java:564)
  locked <0x00000006c30ae7b0> (a org.apache.flume.api.NettyAvroRpcClient)
  at org.apache.flume.api.RpcClientFactory.getInstance(RpcClientFactory.java:88)
  at org.apache.flume.api.LoadBalancingRpcClient.createClient(LoadBalancingRpcClient.java:214)
  at org.apache.flume.api.LoadBalancingRpcClient.getClient(LoadBalancingRpcClient.java:205)
  locked <0x00000006a97b18e8> (a org.apache.flume.api.LoadBalancingRpcClient)
  at org.apache.flume.api.LoadBalancingRpcClient.appendBatch(LoadBalancingRpcClient.java:95)
  at com.ean.platform.components.tlog.client.service.AvroRpcEventRouter$1.call(AvroRpcEventRouter.java:45)
  at com.ean.platform.components.tlog.client.service.AvroRpcEventRouter$1.call(AvroRpcEventRouter.java:43)
{noformat}

The solution is very simple, and a patch should be along in a moment.



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