https://www.cnblogs.com/aquester/p/9891477.html
大压力下Redis参数调整要点
调整以下参数，可以大幅度改善Redis集群的稳定性：
记录一次redis集群一次排查过程：
https://blog.csdn.net/daiyudong2020/article/details/52496725
总结来说，有以下几个问题：
1.由于cluster-node-timeout设置比较短，慢查询KEYS导致了集群判断节点8371失联
2.由于8371失联，导致8373升级为主，开始主从同步
3.由于配置client-output-buffer-limit的限制，导致第一次全量同步失败了
4.又由于PHP客户端的连接池有问题，疯狂连接服务器，产生了类似SYN攻击的效果
5.第一次全量同步失败后，从节点重连主节点花了30秒（超过了最大连接数1w）
关于client-output-buffer-limit参数：
# The syntax of every client-output-buffer-limit directive is the following:
#
# client-output-buffer-limit <class> <hard limit> <soft limit> <soft seconds>
#
# A client is immediately disconnected once the hard limit is reached, or if
# the soft limit is reached and remains reached for the specified number of
# seconds (continuously).
# So for instance if the hard limit is 32 megabytes and the soft limit is
# 16 megabytes / 10 seconds, the client will get disconnected immediately
# if the size of the output buffers reach 32 megabytes, but will also get
# disconnected if the client reaches 16 megabytes and continuously overcomes
# the limit for 10 seconds.
#
# By default normal clients are not limited because they don't receive data
# without asking (in a push way), but just after a request, so only
# asynchronous clients may create a scenario where data is requested faster
# than it can read.
#
# Instead there is a default limit for pubsub and slave clients, since
# subscribers and slaves receive data in a push fashion.
#
# Both the hard or the soft limit can be disabled by setting them to zero.
client-output-buffer-limit normal 0 0 0
client-output-buffer-limit slave 256mb 64mb 60
client-output-buffer-limit pubsub 32mb 8mb 60
采取措施：
1.单实例的切割到4G以下，否则发生主从切换会耗时很长
2.调整client-output-buffer-limit参数，防止同步进行到一半失败
3.调整cluster-node-timeout，不能少于15s
4.禁止任何耗时超过cluster-node-timeout的慢查询，因为会导致主从切换
5.修复客户端类似SYN攻击的疯狂连接方式
————————————————
版权声明：本文为CSDN博主「带鱼兄」的原创文章，遵循CC 4.0 BY-SA版权协议，转载请附上原文出处链接及本声明。
原文链接：https://blog.csdn.net/daiyudong2020/article/details/52496725
Redis配置参数详解
https://blog.csdn.net/ljl890705/article/details/51540427