18/12/02 19:07:36 INFO graph.ComputeCallable: call: Computation took 27.80304 secs for 1 partitions on superstep 2.  Flushing started (time waiting on partitions was 0.00 s, time processing partitions was 3.68 s, time spent on gc was 24.13 s)
18/12/02 19:07:36 INFO worker.BspServiceWorker: finishSuperstep: Waiting on all requests, superstep 2 Memory (free/total/max) = 4192.91M / 13653.50M / 13653.50M
18/12/02 19:07:36 INFO netty.NettyClient: waitAllRequests: Finished all requests. MBytes/sec received = 0, MBytesReceived = 0.0001, ave received req MBytes = 0, secs waited = 28.463
MBytes/sec sent = 0, MBytesSent = 0.0006, ave sent req MBytes = 0.0001, secs waited = 28.463
18/12/02 19:07:36 INFO worker.WorkerAggregatorHandler: finishSuperstep: Start gathering aggregators, workers will send their aggregated values once they are done with superstep computation
18/12/02 19:07:36 WARN netty.NettyClient: getNextChannel: Unlikely event that the channel [id: 0x57316b8b, 0.0.0.0/0.0.0.0:38144 :> ip-172-31-20-236/172.31.20.236:30001] was already removed!
18/12/02 19:07:36 INFO netty.NettyClient: getNextChannel: Fixing disconnected channel to ip-172-31-20-236/172.31.20.236:30001, open = false, bound = false
18/12/02 19:07:36 INFO netty.NettyClient: Using Netty without authentication.
18/12/02 19:07:36 WARN netty.NettyClient: getNextChannel: Failed to reconnect to ip-172-31-20-236/172.31.20.236:30001 on attempt 1 out of 1000 max attempts, sleeping for 5 secs
java.net.ConnectException: Connection refused: ip-172-31-20-236/172.31.20.236:30001
	at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
	at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:717)
	at io.netty.channel.socket.nio.NioSocketChannel.doFinishConnect(NioSocketChannel.java:208)
	at io.netty.channel.nio.AbstractNioChannel$AbstractNioUnsafe.finishConnect(AbstractNioChannel.java:287)
	at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:528)
	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:116)
	at java.lang.Thread.run(Thread.java:748)
...
18/12/02 19:09:21 INFO zookeeper.ClientCnxn: Unable to read additional data from server sessionid 0x167705038550007, likely server has closed socket, closing socket connection and attempting reconnect