前言

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警告信息

如下所示：

# WARNING: The TCP backlog setting of 511 cannot be enforced because
/proc/sys/net/core/somaxconn is set to the lower value of 128
# WARNING overcommit_memory is set to 0! Background save may fail under low memory condition. To fix this issue add 'vm.overcommit_memory = 1' to /etc/sysctl.conf and then reboot or run the command 'sysctl vm.overcommit_memory=1' for this to take effect.
# WARNING you have Transparent Huge Pages (THP) support enabled in your kernel. This will create latency and memory usage issues with Redis. To fix this issue run the command 'echo never > /sys/kernel/mm/transparent_hugepage/enabled' as root, and add it to your /etc/rc.local in order to retain the setting after a reboot. Redis must be restarted after THP is disabled.

解决办法

关于TCP backlog的设置

• 提示信息

WARNING: The TCP backlog setting of 511 cannot be enforced because
/proc/sys/net/core/somaxconn is set to the lower value of 128

tcp 连接数设置为 128 太小

• 处理措施(宿主机执行操作)

]# cat >> /etc/sysctl.conf <<-EOF
net.core.somaxconn=551   # 这里的数据根据生产的需要和电脑的性能进行调整，必须大于等于 551
EOF
]# sysctl -p

关于overcommit_memory的设置

• 提示信息

WARNING overcommit_memory is set to 0! Background save may fail under low memory condition. To fix this issue add 'vm.overcommit_memory = 1' to /etc/sysctl.conf and then reboot or run the command 'sysctl vm.overcommit_memory=1' for this to take effect.

overcommit_memory 的值设置为0时 在低内存条件下，后台保存可能会失败

• 处理措施(宿主机执行操作)

]# cat >> /etc/sysctl.conf <<-EOF
vm.overcommit_memory=1
EOF
]# sysctl -p

关于 THP 支持的设置

• 提示信息

WARNING you have Transparent Huge Pages (THP) support enabled in your kernel. This will create latency and memory usage issues with Redis. To fix this issue run the command 'echo never > /sys/kernel/mm/transparent_hugepage/enabled' as root, and add it to your /etc/rc.local in order to retain the setting after a reboot. Redis must be restarted after THP is disabled.

内核中启用了透明大页面（THP）支持。 这将导致Redis的延迟和内存使用问题

• 处理措施(宿主机执行操作)

]# cat >> /etc/rc.local <<-EOF
echo never > /sys/kernel/mm/transparent_hugepage/enabled
EOF
]# chmod +x /etc/rc.local
]# source /etc/rc.local

重启redis服务

]# /data/deploy/redis
]# docker-compose down
]# docker-compose up -d
]# docker exec redis cat /proc/sys/net/core/somaxconn
128

• 当发现somaxconn的值还是128，没变为551时，说明没有在容器中生效，需要在容器执行命令，新部署redis的docker-compose.yml文件如下所示

version: "3.5"
services:
  redis:
    image: redis:5.0.0
    container_name: redis
    hostname: redis
    privileged: true
    user: root
    ports:
      - 6379:6379
    command:          # 多个命令同时执行
      - /bin/bash 
      - -c 
      - |                 
        echo 551 > /proc/sys/net/core/somaxconn	# 关键命令
        redis-server --requirepass na1234
    volumes:
      - /etc/timezone:/etc/timezone:ro
      - /etc/localtime:/etc/localtime:ro
      - /data/volume/redis:/data
    restart: always
    tty: true

更新部署

]# docker-compose up -d
]# docker exec redis cat /proc/sys/net/core/somaxconn
551

结语

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