How to change Elasticsearch max memory size

I have an Apache server with a default configuration of Elasticsearch and everything works perfectly, except that the default configuration has a max size of 1GB.

I don't have such a large number of documents to store in Elasticsearch, so I want to reduce the memory.

I have seen that I have to change the -Xmx parameter in the Java configuration, but I don't know how.

I have seen I can execute this:

bin/ElasticSearch -Xmx=2G -Xms=2G

But when I have to restart Elasticsearch this will be lost.

Is it possible to change max memory usage when Elasticsearch is installed as a service?

In ElasticSearch >= 5 the documentation has changed, which means none of the above answers worked for me.

I tried changing ES_HEAP_SIZE in /etc/default/elasticsearch and in /etc/init.d/elasticsearch, but when I ran ps aux | grep elasticsearch the output still showed:

/usr/bin/java -Xms2g -Xmx2g # aka 2G min and max ram

I had to make these changes in:

/etc/elasticsearch/jvm.options

# Xms represents the initial size of total heap space
# Xmx represents the maximum size of total heap space

-Xms1g 
-Xmx1g 
# the settings shipped with ES 5 were: -Xms2g
# the settings shipped with ES 5 were: -Xmx2g

Updated on Nov 24, 2016: Elasticsearch 5 apparently has changed the way to configure the JVM. See this answer here. The answer below still applies to versions < 5.

tirdadc, thank you for pointing this out in your comment below.

I have a pastebin page that I share with others when wondering about memory and ES. It's worked OK for me: http://pastebin.com/mNUGQCLY. I'll paste the contents here as well:

References:

https://github.com/grigorescu/Brownian/wiki/ElasticSearch-Configuration http://www.elasticsearch.org/guide/reference/setup/installation/

Edit the following files to modify memory and file number limits. These instructions assume Ubuntu 10.04, may work on later versions and other distributions/OSes. (Edit: This works for Ubuntu 14.04 as well.)

/etc/security/limits.conf:

elasticsearch - nofile 65535
elasticsearch - memlock unlimited

/etc/default/elasticsearch (on CentOS/RH: /etc/sysconfig/elasticsearch ):

ES_HEAP_SIZE=512m
MAX_OPEN_FILES=65535
MAX_LOCKED_MEMORY=unlimited

/etc/elasticsearch/elasticsearch.yml:

bootstrap.mlockall: true

For anyone looking to do this on Centos 7 or with another system running SystemD, you change it in

/etc/sysconfig/elasticsearch 

Uncomment the ES_HEAP_SIZE line, and set a value, eg:

# Heap Size (defaults to 256m min, 1g max)
ES_HEAP_SIZE=16g

(Ignore the comment about 1g max - that's the default)