1. edit     /etc/elasticsearch/jvm.options and set

-Xms8g
-Xmx8g

2. edit      /etc/elasticsearch/elasticsearch.yml 

bootstrap.memory_lock: true

3. edit /etc/default/elasticsearch 

ES_JAVA_OPTS="-Xms8g -Xmx8g"
MAX_LOCKED_MEMORY=unlimited

3. systemctl edit elasticsearch

[Service]
LimitMEMLOCK=infinity

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