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18903:M 09 Aug 01:50:09.749 # WARNING: The TCP backlog setting of 511 cannot be enforced because /proc/sys/net/core/somaxconn is set
 
 to the lower value of 128.
18903:M 09 Aug 01:50:09.749 # Server started, Redis version 3.2.3
18903:M 09 Aug 01:50:09.749 # 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.
18903:M 09 Aug 01:50:09.750 # 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.

目前是懷疑阿里雲的預設yum安裝REDIS有此問題