问运行Flink内置程序有时会出现Exception:java.io.IOException:连接通道失败

EN

java.io.IOException: Connecting the channel failed: Connecting to remote task manager + 'ccr202/127.0.0.2:49651' has failed. This might indicate that the remote task manager has been lost.
at org.apache.flink.runtime.io.network.netty.PartitionRequestClientFactory$ConnectingChannel.waitForChannel(PartitionRequestClientFactory.java:197)
at org.apache.flink.runtime.io.network.netty.PartitionRequestClientFactory$ConnectingChannel.access$000(PartitionRequestClientFactory.java:132)
at org.apache.flink.runtime.io.network.netty.PartitionRequestClientFactory.createPartitionRequestClient(PartitionRequestClientFactory.java:84)
at org.apache.flink.runtime.io.network.netty.NettyConnectionManager.createPartitionRequestClient(NettyConnectionManager.java:59)
at org.apache.flink.runtime.io.network.partition.consumer.RemoteInputChannel.requestSubpartition(RemoteInputChannel.java:156)
at org.apache.flink.runtime.io.network.partition.consumer.SingleInputGate.requestPartitions(SingleInputGate.java:480)
at org.apache.flink.runtime.io.network.partition.consumer.SingleInputGate.getNextBufferOrEvent(SingleInputGate.java:502)
at org.apache.flink.streaming.runtime.io.BarrierTracker.getNextNonBlocked(BarrierTracker.java:93)
at org.apache.flink.streaming.runtime.io.StreamInputProcessor.processInput(StreamInputProcessor.java:214)
at org.apache.flink.streaming.runtime.tasks.OneInputStreamTask.run(OneInputStreamTask.java:69)
at org.apache.flink.streaming.runtime.tasks.StreamTask.invoke(StreamTask.java:264)
at org.apache.flink.runtime.taskmanager.Task.run(Task.java:718)
at java.lang.Thread.run(Thread.java:748)
Caused by: org.apache.flink.runtime.io.network.netty.exception.RemoteTransportException: Connecting to remote task manager + 'ccr202/127.0.0.2:49651' has failed. This might indicate that the remote task manager has been lost.
at org.apache.flink.runtime.io.network.netty.PartitionRequestClientFactory$ConnectingChannel.operationComplete(PartitionRequestClientFactory.java:220)
at org.apache.flink.runtime.io.network.netty.PartitionRequestClientFactory$ConnectingChannel.operationComplete(PartitionRequestClientFactory.java:132)
at org.apache.flink.shaded.netty4.io.netty.util.concurrent.DefaultPromise.notifyListener0(DefaultPromise.java:680)
at org.apache.flink.shaded.netty4.io.netty.util.concurrent.DefaultPromise.notifyListeners0(DefaultPromise.java:603)
at org.apache.flink.shaded.netty4.io.netty.util.concurrent.DefaultPromise.notifyListeners(DefaultPromise.java:563)
at org.apache.flink.shaded.netty4.io.netty.util.concurrent.DefaultPromise.tryFailure(DefaultPromise.java:424)
at org.apache.flink.shaded.netty4.io.netty.channel.nio.AbstractNioChannel$AbstractNioUnsafe.fulfillConnectPromise(AbstractNioChannel.java:268)
at org.apache.flink.shaded.netty4.io.netty.channel.nio.AbstractNioChannel$AbstractNioUnsafe.finishConnect(AbstractNioChannel.java:284)
at org.apache.flink.shaded.netty4.io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:528)
at org.apache.flink.shaded.netty4.io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:468)
at org.apache.flink.shaded.netty4.io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:382)
at org.apache.flink.shaded.netty4.io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:354)
at org.apache.flink.shaded.netty4.io.netty.util.concurrent.SingleThreadEventExecutor$2.run(SingleThreadEventExecutor.java:111)
... 1 more
Caused by: java.net.ConnectException: Connection refused: ccr202/127.0.0.2:49651
at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:717)
at org.apache.flink.shaded.netty4.io.netty.channel.socket.nio.NioSocketChannel.doFinishConnect(NioSocketChannel.java:224)
at org.apache.flink.shaded.netty4.io.netty.channel.nio.AbstractNioChannel$AbstractNioUnsafe.finishConnect(AbstractNioChannel.java:281)
... 6 more