我有nginx上游的redis服务器（5台服务器上有4个redis实例），如下所示：
upstream redis_cluster { server 10.0.1.8:6379 fail_timeout=0; server 10.0.1.8:6380 fail_timeout=0; server 10.0.1.8:6381 fail_timeout=0; server 10.0.1.8:6382 fail_timeout=0; server 10.0.1.6:6379 fail_timeout=0; server 10.0.1.6:6380 fail_timeout=0; server 10.0.1.6:6381 fail_timeout=0; server 10.0.1.6:6382 fail_timeout=0; ... keepalive 16; } 在添加最后一个服务器（实际上是最后4个redis实例）之后，我注意到了一些奇怪的连接：
9684 10.0.0.17:6379 TIME_WAIT 3 10.0.0.17:6380 ESTABLISHED 9677 10.0.0.17:6380 TIME_WAIT 9664 10.0.0.17:6381 TIME_WAIT 6 10.0.0.17:6382 ESTABLISHED 9660 10.0.0.17:6382 TIME_WAIT 4 10.0.1.3:6379 ESTABLISHED 1 10.0.1.3:6379 SYN_SENT 9671 10.0.1.3:6379 TIME_WAIT 3 10.0.1.3:6380 ESTABLISHED 9665 10.0.1.3:6380 TIME_WAIT 1 10.0.1.3:6381 ESTABLISHED 9661 10.0.1.3:6381 TIME_WAIT 5 10.0.1.3:6382 ESTABLISHED 9660 10.0.1.3:6382 TIME_WAIT 5 10.0.0.7:6379 ESTABLISHED 9653 10.0.0.7:6379 TIME_WAIT 4 10.0.0.7:6380 ESTABLISHED 9663 10.0.0.7:6380 TIME_WAIT 1 10.0.0.7:6381 ESTABLISHED 9664 10.0.0.7:6381 TIME_WAIT 7 10.0.0.7:6382 ESTABLISHED 9667 10.0.0.7:6382 TIME_WAIT 5 10.0.1.8:6379 ESTABLISHED 9673 10.0.1.8:6379 TIME_WAIT 2 10.0.1.8:6380 ESTABLISHED 9676 10.0.1.8:6380 TIME_WAIT 4 10.0.1.8:6381 ESTABLISHED 9665 10.0.1.8:6381 TIME_WAIT 3 10.0.1.8:6382 ESTABLISHED
在注释掉最后一个服务器（最后4个上游条目）后，一切正常：
4 10.0.0.10:6379 ESTABLISHED 4 10.0.0.10:6380 ESTABLISHED 4 10.0.0.10:6381 ESTABLISHED 1 10.0.0.10:6381 TIME_WAIT 4 10.0.0.10:6382 ESTABLISHED 4 10.0.1.3:6379 ESTABLISHED 4 10.0.1.3:6380 ESTABLISHED 4 10.0.1.3:6381 ESTABLISHED 4 10.0.1.3:6382 ESTABLISHED 4 10.0.0.7:6379 ESTABLISHED 4 10.0.0.7:6380 ESTABLISHED 4 10.0.0.7:6381 ESTABLISHED 4 10.0.0.7:6382 ESTABLISHED 4 10.0.1.8:6379 ESTABLISHED 4 10.0.1.8:6380 ESTABLISHED 4 10.0.1.8:6381 ESTABLISHED 4 10.0.1.8:6382 ESTABLISHED
这可能是什么原因？ 先谢谢了，同志们。