conf/cassandra-env.sh

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# 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 '/Mem:/ {print $2}'`
            system_cpu_cores=`egrep -c 'processor([[:space:]]+):.*' /proc/cpuinfo`
            break
        ;;
        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}'`
            break
        ;;
        SunOS)
            system_memory_in_mb=`prtconf | awk '/Memory size:/ {print $3}'`
            system_cpu_cores=`psrinfo | wc -l`
            break
        ;;
        *)
            # assume reasonable defaults for e.g. a modern desktop or
            # cheap server
            system_memory_in_mb="2048"
            system_cpu_cores="2"
        ;;
    esac

    # 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
}

# Override these to set the amount of memory to allocate to the JVM at
# start-up. For production use you almost certainly want 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"

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

# Specifies the default port over which Cassandra will be available for
# JMX connections.
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
check_openjdk=`"${JAVA:-java}" -version 2>&1 | awk '{if (NR == 2) {print $1}}'`
if [ "$check_openjdk" != "OpenJDK" ]
then
    JVM_OPTS="$JVM_OPTS -javaagent:$CASSANDRA_HOME/lib/jamm-0.2.5.jar"
fi

# 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

if [ "`uname`" = "Linux" ] ; then
    # reduce the per-thread stack size to minimize the impact of Thrift
    # thread-per-client.  (Best practice is for client connections to
    # be pooled anyway.) Only do so on Linux where it is known to be
    # supported.
    JVM_OPTS="$JVM_OPTS -Xss128k"
fi

# 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"

# 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"

# uncomment to have Cassandra JVM listen for remote debuggers/profilers on port 1414
# JVM_OPTS="$JVM_OPTS -Xdebug -Xnoagent -Xrunjdwp: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="$JVM_OPTS -Djava.rmi.server.hostname=<public name>"
# 
# see 
# https://blogs.oracle.com/jmxetc/entry/troubleshooting_connection_problems_in_jconsole
# for more on configuring JMX through firewalls, etc. (Short version:
# get it working with no firewall first.)
JVM_OPTS="$JVM_OPTS -Dcom.sun.management.jmxremote.port=$JMX_PORT" 
JVM_OPTS="$JVM_OPTS -Dcom.sun.management.jmxremote.ssl=false" 
JVM_OPTS="$JVM_OPTS -Dcom.sun.management.jmxremote.authenticate=false"