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A place to hold mainly reading notes, and some technical stuff occasionally. 这里主要是一些读书笔记、感悟；还有部分技术相关的内容。

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Failed to close the ServletOutputStream connection cleanly, Broken pipe

发布：2018-11-14 Wednesday 标签：WebSocket

目录[-]

Problem1: 服务端报错：Broken pipe

java.io.IOException: Connection timed out
  at sun.nio.ch.FileDispatcherImpl.read0(Native Method)
  at sun.nio.ch.SocketDispatcher.read(SocketDispatcher.java:39)
  at sun.nio.ch.IOUtil.readIntoNativeBuffer(IOUtil.java:223)
  at sun.nio.ch.IOUtil.read(IOUtil.java:197)
  at sun.nio.ch.SocketChannelImpl.read(SocketChannelImpl.java:380)
  at org.apache.tomcat.util.net.SecureNioChannel.read(SecureNioChannel.java:581)
  at org.apache.tomcat.util.net.NioEndpoint$NioSocketWrapper.fillReadBuffer(NioEndpoint.java:1248)
  at org.apache.tomcat.util.net.NioEndpoint$NioSocketWrapper.fillReadBuffer(NioEndpoint.java:1221)
  at org.apache.tomcat.util.net.NioEndpoint$NioSocketWrapper.read(NioEndpoint.java:1194)
  at org.apache.tomcat.websocket.server.WsFrameServer.onDataAvailable(WsFrameServer.java:72)
  at org.apache.tomcat.websocket.server.WsFrameServer.doOnDataAvailable(WsFrameServer.java:171)
  at org.apache.tomcat.websocket.server.WsFrameServer.notifyDataAvailable(WsFrameServer.java:151)
  at org.apache.tomcat.websocket.server.WsHttpUpgradeHandler.upgradeDispatch(WsHttpUpgradeHandler.java:148)
  at org.apache.coyote.http11.upgrade.UpgradeProcessorInternal.dispatch(UpgradeProcessorInternal.java:54)
  at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:53)
  at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:790)
  at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1459)
  at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
  at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
  at java.lang.Thread.run(Thread.java:748)
05-Nov-2018 09:17:07.881 INFO [https-jsse-nio-443-exec-6] org.apache.tomcat.websocket.server.WsRemoteEndpointImplServer.doClose Failed to close the ServletOutputStream connection cleanly
 java.io.IOException: Broken pipe
  at sun.nio.ch.FileDispatcherImpl.write0(Native Method)
  at sun.nio.ch.SocketDispatcher.write(SocketDispatcher.java:47)
  at sun.nio.ch.IOUtil.writeFromNativeBuffer(IOUtil.java:93)
  at sun.nio.ch.IOUtil.write(IOUtil.java:65)
  at sun.nio.ch.SocketChannelImpl.write(SocketChannelImpl.java:471)
  at org.apache.tomcat.util.net.SecureNioChannel.flush(SecureNioChannel.java:144)
  at org.apache.tomcat.util.net.SecureNioChannel.close(SecureNioChannel.java:526)
  at org.apache.tomcat.util.net.NioEndpoint$NioSocketWrapper.close(NioEndpoint.java:1209)
  at org.apache.tomcat.websocket.server.WsRemoteEndpointImplServer.doClose(WsRemoteEndpointImplServer.java:167)
  at org.apache.tomcat.websocket.WsRemoteEndpointImplBase.close(WsRemoteEndpointImplBase.java:710)
  at org.apache.tomcat.websocket.WsSession.onClose(WsSession.java:518)
  at org.apache.tomcat.websocket.server.WsHttpUpgradeHandler.close(WsHttpUpgradeHandler.java:240)
  at org.apache.tomcat.websocket.server.WsHttpUpgradeHandler.upgradeDispatch(WsHttpUpgradeHandler.java:162)
  at org.apache.coyote.http11.upgrade.UpgradeProcessorInternal.dispatch(UpgradeProcessorInternal.java:54)
  at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:53)
  at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:790)
  at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1459)
  at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
  at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
  at java.lang.Thread.run(Thread.java:748)

报出超时的原因可能是后端在向前端发起数据请求时，没有成功。可能的原因是，在服务端，负责和前端通信的websocket连接Session存放在一个Map中，当由于某种未知的原因，导致前后端连接断开后，即客户端失联了，但是Map里的Session并未被移除。所以当服务端有新消息要发送给这个已经失联的Session，便会报错：Connection timed out, Broken pipe。

Solution：当产生这个异常后，后端从Map中移除(remove)已断开连接的客户端Session。

Note：也可以在前端把错误打印出来：WebSocket断开时，会触发CloseEvent, CloseEvent的code字段表示了WebSocket断开的原因。可以从该字段中分析断开的原因。

CloseEvent的三个字段：

CloseEvent.code: code是错误码，是整数类型
CloseEvent.reason: reason是断开原因，是字符串
CloseEvent.wasClean: wasClean表示是否正常断开，是布尔值。一般异常断开时，该值为false

websocket.onclose = function (e) {
     console.log('WebSocket连接断开：Code:' + e.code + ' Reason:' + e.reason + ' wasClean:' + e.wasClean);
}

Problem2: 客户端断开后，如何做到尝试再次连接，即断线重连

Solution: websocket断线重连解决方案: ReconnectingWebSocket

let ws = new WebSocket('ws://host:port');
// 替换为：
let ws = new ReconnectingWebSocket('ws://host:port');

当然ReconnectingWebSocket中还有其他诸如重试间隔等各类配置项，可以查看文档或源码。

Note：如果服务器域名为HTTPS，那么使用的WebSocket协议也必须是wss

If you have any questions or any bugs are found, please feel free to contact me.

Your comments and suggestions are welcome!

Heartsuit's Simple Blog

Failed to close the ServletOutputStream connection cleanly, Broken pipe

Problem1: 服务端报错：Broken pipe

Problem2: 客户端断开后，如何做到尝试再次连接，即断线重连

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