RAM usage increses with redis

[divyaprabhanna]

Hi ,

We are using redis as a cache store for our application . Each key is set with a TTl(Time to live) so that the cache store will not grow . But even though the number of keys stored was less and memory size occupied showed 2gb with the redis-cli INFO command . But the actual RAM usage of the system was huge , it was around 80 gb . AOF is also turned off .

Can you please let me know why the memory usage is so high .

[dspezia]

Probably because at a point, Redis actually needed the 80 Gb of memory. Like most Unix/Linux applications, Redis is often unable to give the memory back to the system once it has been allocated. This is just the way memory allocators work on Unix/Linux. You can check the used_memory_peak[_human] field in INFO to confirm it.

There are many reasons Redis may accumulate memory:

• to store your own data
• to buffer inbound or outbound traffic
• to buffer a replication stream
• to store the SLOWLOG

It is difficult to say what happened for your application without more information.

[ghost]

Memory leak ??

[dspezia]

AFAIK, there is no known memory leak in Redis. Anyway, if the used_memory value is low, it means Redis has correctly freed the memory.