How to set Redis max memory?

Question

I find the configure in this, it just said the command to use the specify configure:

./redis-server <path>/redis.conf

But,I have no idea about how to write the configure. So I have find the default configure in this. But, I still don't understand how to set max memory. Does it just add this line in configure?

maxmemory 2mb

By the way, I want to know how much the default memory is. and I want to set the memory to 2GB, how to do it?

Then, I have added this line to the redis configure to set maxmemory to 40GB:

maxmemory 41943040

And I use the command in redis-cli:

config get maxmemory

it show me:

127.0.0.1:6379> config get maxmemory
1) "maxmemory"
2) "41943040"

But, my java program throw the exception like this when key number is about 200000:

Exception in thread "Thread-228" redis.clients.jedis.exceptions.JedisDataException: OOM command not allowed when used memory > 'maxmemory'.
    at redis.clients.jedis.Protocol.processError(Protocol.java:117)
    at redis.clients.jedis.Protocol.process(Protocol.java:151)
    at redis.clients.jedis.Protocol.read(Protocol.java:205)
    at redis.clients.jedis.Connection.readProtocolWithCheckingBroken(Connection.java:297)
    at redis.clients.jedis.Connection.getStatusCodeReply(Connection.java:196)
    at redis.clients.jedis.Jedis.hmset(Jedis.java:644)
    at cn.ict.dt2redis.analyser.AbstractAnalyser.pushOne(AbstractAnalyser.java:21)
    at cn.ict.dt2redis.analyser.BatchAbstractAnalyser.run(BatchAbstractAnalyser.java:16)
    at java.lang.Thread.run(Thread.java:722)

I have no idea about it, do I success in setting max memory to 40 GB? How to do it? please give me some code in detail.

score 69 · Accepted Answer · edited Oct 14 '19 at 09:19

69

Yes - to set the memory limit just uncomment the maxmemory line in the .conf file. The default is 0, which means unlimited (until the operating system runs out of RAM and kills the process - I recommend to always set maxmemory to a sane value).

Updated: as @Eric Uldall mentioned in the comments, a CONFIG SET maxmemory <sane value>, followed by a CONFIG REWRITE should also do the trick. This will modify your redis.conf to preserve changes in case of restart

edited Oct 14 '19 at 09:19

Jim Aho

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answered Oct 14 '15 at 07:48

Itamar Haber

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I have added the line "maxmemory 41943040" to set max memory 40GB,but it throw exception "OOM command not allowed when used memory > 'maxmemory'." – v11 Oct 14 '15 at 07:56
4

You've set maxmemory to 41943040 bytes = 40960KB = 40MB – Itamar Haber Oct 14 '15 at 08:16
4

Oh,I see. I have changed to "maxmemory 40gb" to test. Thanks! – v11 Oct 14 '15 at 08:19
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It's also worth noting. If you run `config rewrite` after `config set [key] [value]` it will commit the changes to your redis.conf so it will be preserved in the event of a restart. – Eric Uldall Dec 07 '17 at 19:27
@EricUldall very true :) – Itamar Haber Dec 08 '17 at 14:39
can we set max memory on a set in redis? – Sachin Sharma Nov 30 '18 at 06:58
No, it is not possible to limit individual keys' values – Itamar Haber Nov 30 '18 at 12:00
@ItamarHaber Is it possible to do the same on AWS ElasticCache/Redis Cluster? Thanks – Yair Nevet Dec 09 '20 at 13:40
@YairNevet IDK - I work for Redis Labs, home of Open Source Redis and Redis Cloud :) – Itamar Haber Dec 09 '20 at 14:47
@ItamarHaber Okay, Thanks :) – Yair Nevet Dec 09 '20 at 14:57

score 36 · Answer 2 · answered May 31 '18 at 16:36

The documentation in the comments call out bytes but I've used extensions such as mb & gb without any issues.

$ grep ^maxmemory /etc/redis-server.conf
maxmemory 8gb
maxmemory-policy allkeys-lru

And to confirm:

$ redis-cli
...
127.0.0.1:6379> config get maxmemory
1) "maxmemory"
2) "8589934592"

score 15 · Answer 3 · edited Apr 10 '23 at 17:50

No need of changing any thing in the .conf file just follow the following steps

Step 1: First check whether redis-server is working or not

$ redis-cli
127.0.0.1:6379> ping
PONG

if the reply is PONG then your server is working absolutely fine.

Step 2: To get the current max memory run the following commands:

$ redis-cli
127.0.0.1:6379> config get maxmemory
1) "maxmemory"
2) "0"

Initially it is set to 0 by default.

Step 3: After running the above step run the following commands to set the maxmemory:

127.0.0.1:6379> config set maxmemory 128M
OK

To check whether the maxmemory is set to 128M run step 2 again.

Step 4: After changing the maxmemory restart the redis-server

$ sudo systemctl restart redis
OR
$ sudo systemctl restart redis-server

score 8 · Answer 4 · answered Jan 31 '18 at 16:14

8

maxmemory 41943040

option set in bytes, so you set 40MB

answered Jan 31 '18 at 16:14

Max

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score 1 · Answer 5 · answered Sep 10 '19 at 02:38

If anyone is still having trouble setting the maxmemory config setting in a local environment, the actual steps are as follows:

In a terminal, start your redis instance redis-server
In a new terminal window run redis-cli
In the new terminal window (step 2) run config set maxmemory 2mb
Verify maxmemory by running config get maxmemory in same terminal window as steps 2/3

Somewhat documented here under the Changing Redis configuration while the server is running section

score 1 · Answer 6 · answered Dec 21 '19 at 21:32

Since this is an old question, users who are reading in 2019 and using Ubuntu 18.04, the configuration file is located in /etc/redis/redis.conf and if you have installed using (default/recommended method) apt install redis-server the default memory limit is set to "0" which practically means there is "no limit" which can be troublesome if user has limited/small amount of RAM/memory. To set your custom memory limit you may simply edit configuration file and type "maxmemory 1gb" as the very first line. Restart redis service for changes to take effect. To verify changes use redis-cli config get maxmemory

Ubuntu 18.04 users may read more here: How to install and configure REDIS on Ubuntu 18.04

How to set Redis max memory?

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