/etc/default/elasticsearch on Debian

elasticsearch.sh

# Index settings:
# index.store.compress.tv: true
# index.store.compress.stored: true

# Based on Cassandra Java configuration:
# https://svn.apache.org/repos/asf/cassandra/trunk/conf/cassandra-env.sh
calculate_heap_sizes()
{
    system_memory_in_mb=`free -m | awk '/Mem:/ {print $2}'`
    system_cpu_cores=`egrep -c 'processor([[:space:]]+):.*' /proc/cpuinfo`

    # set max heap size based on the following
    # max(min(1/2 ram, 1024MB), min(1/4 ram, 8GB))
    # calculate 1/2 ram and cap to 1024MB
    # calculate 1/4 ram and cap to 8192MB
    # pick the max
    half_system_memory_in_mb=`expr $system_memory_in_mb / 2`
    quarter_system_memory_in_mb=`expr $half_system_memory_in_mb / 2`
    if [ "$half_system_memory_in_mb" -gt "1024" ]
    then
        half_system_memory_in_mb="1024"
    fi

    if [ "$quarter_system_memory_in_mb" -gt "8192" ]
    then
        quarter_system_memory_in_mb="8192"
    fi

    if [ "$half_system_memory_in_mb" -gt "$quarter_system_memory_in_mb" ]
    then
        max_heap_size_in_mb="$half_system_memory_in_mb"
    else
        max_heap_size_in_mb="$quarter_system_memory_in_mb"
    fi

    ES_HEAP_SIZE="${max_heap_size_in_mb}M"

    # Young gen: min(max_sensible_per_modern_cpu_core * num_cores, 1/4 * heap size)
    max_sensible_yg_per_core_in_mb="100"
    max_sensible_yg_in_mb=`expr $max_sensible_yg_per_core_in_mb "*" $system_cpu_cores`

    desired_yg_in_mb=`expr $max_heap_size_in_mb / 4`

    if [ "$desired_yg_in_mb" -gt "$max_sensible_yg_in_mb" ]
    then
        ES_HEAP_NEWSIZE="${max_sensible_yg_in_mb}M"
    else
        ES_HEAP_NEWSIZE="${desired_yg_in_mb}M"
    fi
}

calculate_heap_sizes

# Additional Java OPTS
ES_JAVA_OPTS="-XX:+CMSParallelRemarkEnabled -XX:SurvivorRatio=8 -XX:MaxTenuringThreshold=1"