由MemcachedTCPSession.destroy异常引起的There is no available connection at this moment错误

先看错误信息：
java.lang.NullPointerException
   at net.rubyeye.xmemcached.impl.MemcachedTCPSession.destroy(MemcachedTCPSession.java:112)
   at net.rubyeye.xmemcached.impl.MemcachedHandler.onSessionClosed(MemcachedHandler.java:136)
   at com.google.code.yanf4j.core.impl.AbstractSession.onClosed(AbstractSession.java:305)
   at com.google.code.yanf4j.core.impl.AbstractSession.close(AbstractSession.java:293)
   at com.google.code.yanf4j.nio.impl.NioTCPSession.decode(NioTCPSession.java:302)
   at com.google.code.yanf4j.nio.impl.NioTCPSession.readFromBuffer(NioTCPSession.java:205)
   at com.google.code.yanf4j.nio.impl.AbstractNioSession.onRead(AbstractNioSession.java:198)
   at com.google.code.yanf4j.nio.impl.AbstractNioSession.onEvent(AbstractNioSession.java:343)
   at com.google.code.yanf4j.nio.impl.SocketChannelController.dispatchReadEvent(SocketChannelController.java:56)
   at com.google.code.yanf4j.nio.impl.NioController$ReadTask.run(NioController.java:110)
   at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
   at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
   at java.lang.Thread.run(Thread.java:662)

看了一下MemcachedTCPSession.destroy方法：
public void destroy() {
        Command command = this.currentCommand.get();
        if (command != null) {
            command.setException(new MemcachedException(
                    "Session has been closed"));
            command.getLatch().countDown();
        }
        while ((command = this.commandAlreadySent.poll()) != null) {
            command.setException(new MemcachedException(
                    "Session has been closed"));
            if (command.getLatch() != null) {
                command.getLatch().countDown();
            }
        }

    }

不知为什么第一个command.getLatch().countDown()不判断command.getLatch(
)为null的情况？
出现几次这个异常后，以后的调用会一直抛There is no available 
connection at this moment错误。
个人觉得由于这个异常导致MemcachedHandler方法onSessionClosed中的t
his.reconnect(memcachedSession)不能执行，导致session不能重建，不知
对不对？

版本：1.3.5

Original issue reported on code.google.com by zhaodj1...@gmail.com on 29 Aug 2013 at 11:09

lishunli / xmemcached

由MemcachedTCPSession.destroy异常引起的There is no available connection at this moment错误 #265