conf/cassandra-env.sh

# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements.  See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership.  The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License.  You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

calculate_heap_sizes()
{
    case "`uname`" in
        Linux)
            system_memory_in_mb=`free -m | awk '/:/ {print $2;exit}'`
            system_cpu_cores=`egrep -c 'processor([[:space:]]+):.*' /proc/cpuinfo`
        ;;
        FreeBSD)
            system_memory_in_bytes=`sysctl hw.physmem | awk '{print $2}'`
            system_memory_in_mb=`expr $system_memory_in_bytes / 1024 / 1024`
            system_cpu_cores=`sysctl hw.ncpu | awk '{print $2}'`
        ;;
        SunOS)
            system_memory_in_mb=`prtconf | awk '/Memory size:/ {print $3}'`
            system_cpu_cores=`psrinfo | wc -l`
        ;;
        Darwin)
            system_memory_in_bytes=`sysctl hw.memsize | awk '{print $2}'`
            system_memory_in_mb=`expr $system_memory_in_bytes / 1024 / 1024`
            system_cpu_cores=`sysctl hw.ncpu | awk '{print $2}'`
        ;;
        *)
            # assume reasonable defaults for e.g. a modern desktop or
            # cheap server
            system_memory_in_mb="2048"
            system_cpu_cores="2"
        ;;
    esac

    # some systems like the raspberry pi don't report cores, use at least 1
    if [ "$system_cpu_cores" -lt "1" ]
    then
        system_cpu_cores="1"
    fi

    # 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="$quarter_system_memory_in_mb"
    fi
    MAX_HEAP_SIZE="${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
        HEAP_NEWSIZE="${max_sensible_yg_in_mb}M"
    else
        HEAP_NEWSIZE="${desired_yg_in_mb}M"
    fi
}

# Determine the sort of JVM we'll be running on.

java_ver_output=`"${JAVA:-java}" -version 2>&1`

jvmver=`echo "$java_ver_output" | grep '[openjdk|java] version' | awk -F'"' 'NR==1 {print $2}'`
JVM_VERSION=${jvmver%_*}
JVM_PATCH_VERSION=${jvmver#*_}

if [ "$JVM_VERSION" \< "1.7" ] ; then
    echo "Cassandra 2.0 and later require Java 7 or later."
    exit 1;
fi


jvm=`echo "$java_ver_output" | grep -A 1 'java version' | awk 'NR==2 {print $1}'`
case "$jvm" in
    OpenJDK)
        JVM_VENDOR=OpenJDK
        # this will be "64-Bit" or "32-Bit"
        JVM_ARCH=`echo "$java_ver_output" | awk 'NR==3 {print $2}'`
        ;;
    "Java(TM)")
        JVM_VENDOR=Oracle
        # this will be "64-Bit" or "32-Bit"
        JVM_ARCH=`echo "$java_ver_output" | awk 'NR==3 {print $3}'`
        ;;
    *)
        # Help fill in other JVM values
        JVM_VENDOR=other
        JVM_ARCH=unknown
        ;;
esac


# Override these to set the amount of memory to allocate to the JVM at
# start-up. For production use you may wish to adjust this for your
# environment. MAX_HEAP_SIZE is the total amount of memory dedicated
# to the Java heap; HEAP_NEWSIZE refers to the size of the young
# generation. Both MAX_HEAP_SIZE and HEAP_NEWSIZE should be either set
# or not (if you set one, set the other).
#
# The main trade-off for the young generation is that the larger it
# is, the longer GC pause times will be. The shorter it is, the more
# expensive GC will be (usually).
#
# The example HEAP_NEWSIZE assumes a modern 8-core+ machine for decent pause
# times. If in doubt, and if you do not particularly want to tweak, go with
# 100 MB per physical CPU core.

#MAX_HEAP_SIZE="4G"
#HEAP_NEWSIZE="800M"

# Set this to control the amount of arenas per-thread in glibc
#export MALLOC_ARENA_MAX=4

if [ "x$MAX_HEAP_SIZE" = "x" ] && [ "x$HEAP_NEWSIZE" = "x" ]; then
    calculate_heap_sizes
else
    if [ "x$MAX_HEAP_SIZE" = "x" ] ||  [ "x$HEAP_NEWSIZE" = "x" ]; then
        echo "please set or unset MAX_HEAP_SIZE and HEAP_NEWSIZE in pairs (see cassandra-env.sh)"
        exit 1
    fi
fi

if [ "x$MALLOC_ARENA_MAX" = "x" ]
then
    export MALLOC_ARENA_MAX=4
fi

# Specifies the default port over which Cassandra will be available for
# JMX connections.
# For security reasons, you should not expose this port to the internet.  Firewall it if needed.
JMX_PORT="7199"


# Here we create the arguments that will get passed to the jvm when
# starting cassandra.

# enable assertions.  disabling this in production will give a modest
# performance benefit (around 5%).
JVM_OPTS="$JVM_OPTS -ea"

# add the jamm javaagent
JVM_OPTS="$JVM_OPTS -javaagent:$CASSANDRA_HOME/lib/jamm-0.2.5.jar"

# some JVMs will fill up their heap when accessed via JMX, see CASSANDRA-6541
JVM_OPTS="$JVM_OPTS -XX:+CMSClassUnloadingEnabled"

# enable thread priorities, primarily so we can give periodic tasks
# a lower priority to avoid interfering with client workload
JVM_OPTS="$JVM_OPTS -XX:+UseThreadPriorities"
# allows lowering thread priority without being root.  see
# http://tech.stolsvik.com/2010/01/linux-java-thread-priorities-workaround.html
JVM_OPTS="$JVM_OPTS -XX:ThreadPriorityPolicy=42"

# min and max heap sizes should be set to the same value to avoid
# stop-the-world GC pauses during resize, and so that we can lock the
# heap in memory on startup to prevent any of it from being swapped
# out.
JVM_OPTS="$JVM_OPTS -Xms${MAX_HEAP_SIZE}"
JVM_OPTS="$JVM_OPTS -Xmx${MAX_HEAP_SIZE}"
JVM_OPTS="$JVM_OPTS -Xmn${HEAP_NEWSIZE}"
JVM_OPTS="$JVM_OPTS -XX:+HeapDumpOnOutOfMemoryError"

# set jvm HeapDumpPath with CASSANDRA_HEAPDUMP_DIR
if [ "x$CASSANDRA_HEAPDUMP_DIR" != "x" ]; then
    JVM_OPTS="$JVM_OPTS -XX:HeapDumpPath=$CASSANDRA_HEAPDUMP_DIR/cassandra-`date +%s`-pid$$.hprof"
fi


startswith() { [ "${1#$2}" != "$1" ]; }

# Per-thread stack size.
JVM_OPTS="$JVM_OPTS -Xss256k"

# Larger interned string table, for gossip's benefit (CASSANDRA-6410)
JVM_OPTS="$JVM_OPTS -XX:StringTableSize=1000003"

# GC tuning options
JVM_OPTS="$JVM_OPTS -XX:+UseParNewGC" 
JVM_OPTS="$JVM_OPTS -XX:+UseConcMarkSweepGC" 
JVM_OPTS="$JVM_OPTS -XX:+CMSParallelRemarkEnabled" 
JVM_OPTS="$JVM_OPTS -XX:SurvivorRatio=8" 
JVM_OPTS="$JVM_OPTS -XX:MaxTenuringThreshold=1"
JVM_OPTS="$JVM_OPTS -XX:CMSInitiatingOccupancyFraction=75"
JVM_OPTS="$JVM_OPTS -XX:+UseCMSInitiatingOccupancyOnly"
JVM_OPTS="$JVM_OPTS -XX:+UseTLAB"

# note: bash evals '1.7.x' as > '1.7' so this is really a >= 1.7 jvm check
if { [ "$JVM_VERSION" \> "1.7" ] && [ "$JVM_VERSION" \< "1.8.0" ] && [ "$JVM_PATCH_VERSION" -ge "60" ]; } || [ "$JVM_VERSION" \> "1.8" ] ; then
    JVM_OPTS="$JVM_OPTS -XX:+CMSParallelInitialMarkEnabled -XX:+CMSEdenChunksRecordAlways"
fi

if [ "$JVM_ARCH" = "64-Bit" ] ; then
    JVM_OPTS="$JVM_OPTS -XX:+UseCondCardMark"
fi

# GC logging options -- uncomment to enable
# JVM_OPTS="$JVM_OPTS -XX:+PrintGCDetails"
# JVM_OPTS="$JVM_OPTS -XX:+PrintGCDateStamps"
# JVM_OPTS="$JVM_OPTS -XX:+PrintHeapAtGC"
# JVM_OPTS="$JVM_OPTS -XX:+PrintTenuringDistribution"
# JVM_OPTS="$JVM_OPTS -XX:+PrintGCApplicationStoppedTime"
# JVM_OPTS="$JVM_OPTS -XX:+PrintPromotionFailure"
# JVM_OPTS="$JVM_OPTS -XX:PrintFLSStatistics=1"
# JVM_OPTS="$JVM_OPTS -Xloggc:/var/log/cassandra/gc-`date +%s`.log"
# If you are using JDK 6u34 7u2 or later you can enable GC log rotation
# don't stick the date in the log name if rotation is on.
# JVM_OPTS="$JVM_OPTS -Xloggc:/var/log/cassandra/gc.log"
# JVM_OPTS="$JVM_OPTS -XX:+UseGCLogFileRotation"
# JVM_OPTS="$JVM_OPTS -XX:NumberOfGCLogFiles=10"
# JVM_OPTS="$JVM_OPTS -XX:GCLogFileSize=10M"

# Configure the following for JEMallocAllocator and if jemalloc is not available in the system 
# library path (Example: /usr/local/lib/). Usually "make install" will do the right thing. 
# export LD_LIBRARY_PATH=<JEMALLOC_HOME>/lib/
# JVM_OPTS="$JVM_OPTS -Djava.library.path=<JEMALLOC_HOME>/lib/"

# uncomment to have Cassandra JVM listen for remote debuggers/profilers on port 1414
# JVM_OPTS="$JVM_OPTS -agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=1414"

# Prefer binding to IPv4 network intefaces (when net.ipv6.bindv6only=1). See
# http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6342561 (short version:
# comment out this entry to enable IPv6 support).
JVM_OPTS="$JVM_OPTS -Djava.net.preferIPv4Stack=true"

# jmx: metrics and administration interface
#
# add this if you're having trouble connecting:
# JVM_OPTS="$JVM_OPTS -Djava.rmi.server.hostname=<public name>"
#
# see
# https://blogs.oracle.com/jmxetc/entry/troubleshooting_connection_problems_in_jconsole
# for more on configuring JMX through firewalls, etc. (Short version:
# get it working with no firewall first.)
#
# Cassandra ships with JMX accessible  *only* from localhost.  
# To enable remote JMX connections, change the setting below to enable JMX
# with authentication and/or ssl enabled. See https://wiki.apache.org/cassandra/JmxSecurity 
#
LOCAL_JMX=yes

if [ "$LOCAL_JMX" = "yes" ]; then
  JVM_OPTS="$JVM_OPTS -Dcassandra.jmx.local.port=$JMX_PORT -XX:+DisableExplicitGC"
else
  JVM_OPTS="$JVM_OPTS -Dcom.sun.management.jmxremote.port=$JMX_PORT"
  JVM_OPTS="$JVM_OPTS -Dcom.sun.management.jmxremote.rmi.port=$JMX_PORT"
  JVM_OPTS="$JVM_OPTS -Dcom.sun.management.jmxremote.ssl=false"
  JVM_OPTS="$JVM_OPTS -Dcom.sun.management.jmxremote.authenticate=true"
  JVM_OPTS="$JVM_OPTS -Dcom.sun.management.jmxremote.password.file=/etc/cassandra/jmxremote.password"
fi

JVM_OPTS="$JVM_OPTS $JVM_EXTRA_OPTS"