ki827

I also encountered the same problem. In version 2.3.2, I would encounter this exception as long as I called the stop() method.

> stack trace ``` Java org.apache.mina.core.write.WriteToClosedSessionException: null at org.apache.mina.core.polling.AbstractPollingIoProcessor$Processor.clearWriteRequestQueue(AbstractPollingIoProcessor.java:1192) ~[mina-core-2.2.4.jar:na] at org.apache.mina.core.polling.AbstractPollingIoProcessor$Processor.removeNow(AbstractPollingIoProcessor.java:1153) ~[mina-core-2.2.4.jar:na] at org.apache.mina.core.polling.AbstractPollingIoProcessor$Processor.removeSessions(AbstractPollingIoProcessor.java:864) ~[mina-core-2.2.4.jar:na] at org.apache.mina.core.polling.AbstractPollingIoProcessor$Processor.run(AbstractPollingIoProcessor.java:694) ~[mina-core-2.2.4.jar:na] at org.apache.mina.util.NamePreservingRunnable.run(NamePreservingRunnable.java:64) ~[mina-core-2.2.4.jar:na] at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136) ~[na:na] at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635) ~[na:na] at java.base/java.lang.Thread.run(Thread.java:840)...