TPCH Concurrency Scale tests hit ChannelClosedException

In TPCH Concurrency tests, we try to see how drill scales up with number of threads with each threads running a simple query (tpch query #6). With 96 threads, many threads terminated due to ChannelClosedException and/or FormanException:
2015-10-07 18:01:26 [pip87] ERROR PipSQuawkling executeQuery - [ 0 / 06_par100 ] SYSTEM ERROR: ChannelClosedException

[Error Id: cbae3879-8067-47cd-8c42-91a38896b81a on ucs-node9.perf.lab:31010]
java.sql.SQLException: SYSTEM ERROR: ChannelClosedException

[Error Id: cbae3879-8067-47cd-8c42-91a38896b81a on ucs-node9.perf.lab:31010]
at org.apache.drill.jdbc.impl.DrillCursor.nextRowInternally(DrillCursor.java:247)
at org.apache.drill.jdbc.impl.DrillCursor.loadInitialSchema(DrillCursor.java:290)
at org.apache.drill.jdbc.impl.DrillResultSetImpl.execute(DrillResultSetImpl.java:1359)
at org.apache.drill.jdbc.impl.DrillResultSetImpl.execute(DrillResultSetImpl.java:74)
at net.hydromatic.avatica.AvaticaConnection.executeQueryInternal(AvaticaConnection.java:404)
at net.hydromatic.avatica.AvaticaStatement.executeQueryInternal(AvaticaStatement.java:351)
at net.hydromatic.avatica.AvaticaStatement.executeQuery(AvaticaStatement.java:78)
at org.apache.drill.jdbc.impl.DrillStatementImpl.executeQuery(DrillStatementImpl.java:97)
at PipSQuawkling.executeQuery(PipSQuawkling.java:295)
at PipSQuawkling.executeTest(PipSQuawkling.java:148)
at PipSQuawkling.run(PipSQuawkling.java:76)
Caused by: org.apache.drill.common.exceptions.UserRemoteException: SYSTEM ERROR: ChannelClosedException

[Error Id: cbae3879-8067-47cd-8c42-91a38896b81a on ucs-node9.perf.lab:31010]
at org.apache.drill.exec.rpc.user.QueryResultHandler.resultArrived(QueryResultHandler.java:118)
at org.apache.drill.exec.rpc.user.UserClient.handleReponse(UserClient.java:110)
at org.apache.drill.exec.rpc.BasicClientWithConnection.handle(BasicClientWithConnection.java:47)
at org.apache.drill.exec.rpc.BasicClientWithConnection.handle(BasicClientWithConnection.java:32)
at org.apache.drill.exec.rpc.RpcBus.handle(RpcBus.java:61)
at org.apache.drill.exec.rpc.RpcBus$InboundHandler.decode(RpcBus.java:233)
at org.apache.drill.exec.rpc.RpcBus$InboundHandler.decode(RpcBus.java:205)
at io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:89)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:339)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:324)
at io.netty.handler.timeout.IdleStateHandler.channelRead(IdleStateHandler.java:254)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:339)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:324)
at io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:103)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:339)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:324)
at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:242)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:339)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:324)
at io.netty.channel.ChannelInboundHandlerAdapter.channelRead(ChannelInboundHandlerAdapter.java:86)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:339)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:324)
at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:847)
at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:131)
at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:511)
at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:468)
at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:382)
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:354)
at io.netty.util.concurrent.SingleThreadEventExecutor$2.run(SingleThreadEventExecutor.java:111)
at java.lang.Thread.run(Thread.java:744)

2015-10-07 18:18:12 [pip10] ERROR PipSQuawkling fetchRows - [ 1 / 06_par100 ] SYSTEM ERROR: ForemanException: One more more nodes lost connectivity during query. Identified nodes were [ucs-node4.perf.lab:31010].

[Error Id: 443e598e-8511-40be-a5f6-9e1c0614a33b on ucs-node9.perf.lab:31010]
java.sql.SQLException: SYSTEM ERROR: ForemanException: One more more nodes lost connectivity during query. Identified nodes were [ucs-node4.perf.lab:31010].

[Error Id: 443e598e-8511-40be-a5f6-9e1c0614a33b on ucs-node9.perf.lab:31010]
at org.apache.drill.jdbc.impl.DrillCursor.nextRowInternally(DrillCursor.java:247)
at org.apache.drill.jdbc.impl.DrillCursor.next(DrillCursor.java:320)
at net.hydromatic.avatica.AvaticaResultSet.next(AvaticaResultSet.java:187)
at org.apache.drill.jdbc.impl.DrillResultSetImpl.next(DrillResultSetImpl.java:160)
at PipSQuawkling.fetchRows(PipSQuawkling.java:330)
at PipSQuawkling.executeTest(PipSQuawkling.java:158)
at PipSQuawkling.run(PipSQuawkling.java:76)
Caused by: org.apache.drill.common.exceptions.UserRemoteException: SYSTEM ERROR: ForemanException: One more more nodes lost connectivity during query. Identified nodes were [ucs-node4.perf.lab:31010].

[Error Id: 443e598e-8511-40be-a5f6-9e1c0614a33b on ucs-node9.perf.lab:31010]
at org.apache.drill.exec.rpc.user.QueryResultHandler.resultArrived(QueryResultHandler.java:118)
at org.apache.drill.exec.rpc.user.UserClient.handleReponse(UserClient.java:110)
at org.apache.drill.exec.rpc.BasicClientWithConnection.handle(BasicClientWithConnection.java:47)
at org.apache.drill.exec.rpc.BasicClientWithConnection.handle(BasicClientWithConnection.java:32)
at org.apache.drill.exec.rpc.RpcBus.handle(RpcBus.java:61)
at org.apache.drill.exec.rpc.RpcBus$InboundHandler.decode(RpcBus.java:233)
at org.apache.drill.exec.rpc.RpcBus$InboundHandler.decode(RpcBus.java:205)
at io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:89)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:339)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:324)
at io.netty.handler.timeout.IdleStateHandler.channelRead(IdleStateHandler.java:254)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:339)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:324)
at io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:103)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:339)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:324)
at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:242)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:339)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:324)
at io.netty.channel.ChannelInboundHandlerAdapter.channelRead(ChannelInboundHandlerAdapter.java:86)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:339)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:324)
at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:847)
at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:131)
at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:511)
at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:468)
at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:382)
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:354)
at io.netty.util.concurrent.SingleThreadEventExecutor$2.run(SingleThreadEventExecutor.java:111)
at java.lang.Thread.run(Thread.java:744)

All the drillbits were still alive when the exception was hit.