websocket报错导致连接关闭?报错

RT，websocket当并发连接过多时就容易报错：

Websocket Connection Exception:java.lang.IllegalStateException: The remote endpoint was in state [TEXT_FULL_WRITING] which is an invalid state for called method
Wepsocket Close Connection:userid_ocnBnw9i4CRxXLiFvNZEq0yNb7-8
Jan 12, 2017 3:14:54 PM org.apache.tomcat.websocket.pojo.PojoEndpointBase onClose
SEVERE: Failed to call onClose method of POJO end point for POJO of type [cn.pxzs.train.websocket.ShakeWapSocket]
java.lang.reflect.InvocationTargetException
at sun.reflect.GeneratedMethodAccessor35.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.apache.tomcat.websocket.pojo.PojoEndpointBase.onClose(PojoEndpointBase.java:107)
at org.apache.tomcat.websocket.WsSession.fireEndpointOnClose(WsSession.java:514)
at org.apache.tomcat.websocket.WsSession.onClose(WsSession.java:496)
at org.apache.tomcat.websocket.server.WsHttpUpgradeHandler.close(WsHttpUpgradeHandler.java:184)
at org.apache.tomcat.websocket.server.WsHttpUpgradeHandler.access$200(WsHttpUpgradeHandler.java:47)
at org.apache.tomcat.websocket.server.WsHttpUpgradeHandler$WsReadListener.onDataAvailable(WsHttpUpgradeHandler.java:206)
at org.apache.coyote.http11.upgrade.AbstractServletInputStream.onDataAvailable(AbstractServletInputStream.java:203)
at org.apache.coyote.http11.upgrade.AbstractProcessor.upgradeDispatch(AbstractProcessor.java:93)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:621)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1756)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1715)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.IllegalStateException: The remote endpoint was in state [TEXT_FULL_WRITING] which is an invalid state for called method
at org.apache.tomcat.websocket.WsRemoteEndpointImplBase$StateMachine.checkState(WsRemoteEndpointImplBase.java:1206)
at org.apache.tomcat.websocket.WsRemoteEndpointImplBase$StateMachine.textStart(WsRemoteEndpointImplBase.java:1169)
at org.apache.tomcat.websocket.WsRemoteEndpointImplBase.sendStringByCompletion(WsRemoteEndpointImplBase.java:213)
at org.apache.tomcat.websocket.WsRemoteEndpointImplBase.sendStringByFuture(WsRemoteEndpointImplBase.java:201)
at org.apache.tomcat.websocket.WsRemoteEndpointAsync.sendText(WsRemoteEndpointAsync.java:53)
at cn.pxzs.train.websocket.common.SessionUtils.broadcast(SessionUtils.java:48)
at cn.pxzs.train.websocket.ShakeWapSocket.onClose(ShakeWapSocket.java:76)
... 18 more

不知道哪里出了问题。有没有懂的前辈？