Invokes CassandraDataStoreHandler TransportException

[Dark0096]

I was encountered below situations:

2020-01-05 19:45:31.856 ERROR 1 --- [-3-thread-12139] c.g.w.s.data.CassandraDataStoreHandler   : com.datastax.driver.core.exceptions.TransportException: [/x.x.x.x:9042] Connection has been closed

com.datastax.driver.core.exceptions.TransportException: [/x.x.x.x:9042] Connection has been closed
        at com.datastax.driver.core.Connection$ConnectionCloseFuture.force(Connection.java:1427) ~[cassandra-driver-core-3.8.0.jar!/:na]
        at com.datastax.driver.core.Connection$ConnectionCloseFuture.force(Connection.java:1408) ~[cassandra-driver-core-3.8.0.jar!/:na]
        at com.datastax.driver.core.Connection.defunct(Connection.java:585) ~[cassandra-driver-core-3.8.0.jar!/:na]
        at com.datastax.driver.core.Connection$Dispatcher.exceptionCaught(Connection.java:1330) ~[cassandra-driver-core-3.8.0.jar!/:na]
        at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:297) ~[netty-all-4.1.43.Final.jar!/:4.1.43.Final]
        at io.netty.channel.AbstractChannelHandlerContext.notifyHandlerException(AbstractChannelHandlerContext.java:831) ~[netty-all-4.1.43.Final.jar!/:4.1.43.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeUserEventTriggered(AbstractChannelHandlerContext.java:343) ~[netty-all-4.1.43.Final.jar!/:4.1.43.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeUserEventTriggered(AbstractChannelHandlerContext.java:327) ~[netty-all-4.1.43.Final.jar!/:4.1.43.Final]
        at io.netty.channel.AbstractChannelHandlerContext.fireUserEventTriggered(AbstractChannelHandlerContext.java:319) ~[netty-all-4.1.43.Final.jar!/:4.1.43.Final]
        at io.netty.handler.timeout.IdleStateHandler.channelIdle(IdleStateHandler.java:372) ~[netty-all-4.1.43.Final.jar!/:4.1.43.Final]
        at io.netty.handler.timeout.IdleStateHandler$ReaderIdleTimeoutTask.run(IdleStateHandler.java:505) ~[netty-all-4.1.43.Final.jar!/:4.1.43.Final]
        at io.netty.handler.timeout.IdleStateHandler$AbstractIdleTask.run(IdleStateHandler.java:477) ~[netty-all-4.1.43.Final.jar!/:4.1.43.Final]
        at io.netty.util.concurrent.PromiseTask.runTask(PromiseTask.java:98) ~[netty-all-4.1.43.Final.jar!/:4.1.43.Final]
        at io.netty.util.concurrent.ScheduledFutureTask.run(ScheduledFutureTask.java:150) ~[netty-all-4.1.43.Final.jar!/:4.1.43.Final]
        at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:163) ~[netty-all-4.1.43.Final.jar!/:4.1.43.Final]
        at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:510) ~[netty-all-4.1.43.Final.jar!/:4.1.43.Final]
        at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:413) ~[netty-all-4.1.43.Final.jar!/:4.1.43.Final]
        at io.netty.util.concurrent.SingleThreadEventExecutor$6.run(SingleThreadEventExecutor.java:1050) ~[netty-all-4.1.43.Final.jar!/:4.1.43.Final]
        at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74) ~[netty-all-4.1.43.Final.jar!/:4.1.43.Final]
        at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30) ~[netty-all-4.1.43.Final.jar!/:4.1.43.Final]
        at java.lang.Thread.run(Thread.java:748) [na:1.8.0_222]