JDK8即将收费，所以需要升级jdk11（目前最新的是jdk12，但是没有时间去研究）。
需要迁移的服务中大部分只要升级到最新的版本都可以支持JDK11。但是也有服务不可以的，
RocketMQ最新的是4.4.0版本，至于安装步骤我就不写啦，网上一搜一大把，
但是当RocketMQ4.4.0遇到JDK11后却出现了无法启动nameserver的问题。
原因就是RocketMQ仍然是按着JDK8的配置做为启动的。
废话少说盘他！！
主要修改点如下(修改部分主要在注释前后)：
vim runserver.sh

error_exit ()
{
    echo "ERROR: $1 !!"
    exit 1
}

[ ! -e "$JAVA_HOME/bin/java" ] && JAVA_HOME=$HOME/jdk/java
[ ! -e "$JAVA_HOME/bin/java" ] && JAVA_HOME=/usr/java
[ ! -e "$JAVA_HOME/bin/java" ] && error_exit "Please set the JAVA_HOME variable in your environment, We need java(x64)!"

export JAVA_HOME
export JAVA="$JAVA_HOME/bin/java"
export BASE_DIR=$(dirname $0)/..
export CLASSPATH=${BASE_DIR}/lib/rocketmq-namesrv-4.4.0.jar:${BASE_DIR}/lib/*:${BASE_DIR}/conf:${CLASSPATH}
#export CLASSPATH=.:${BASE_DIR}/conf:${CLASSPATH}
echo "$BASE_DIR"
echo "CLASSPATH:$CLASSPATH"

#===========================================================================================
# JVM Configuration
#===========================================================================================
#JAVA_OPT="${JAVA_OPT} -server -Xms4g -Xmx4g -Xmn2g -XX:MetaspaceSize=128m -XX:MaxMetaspaceSize=320m"
JAVA_OPT="${JAVA_OPT} -server -Xms1g -Xmx1g -Xmn512m -XX:MetaspaceSize=128m -XX:MaxMetaspaceSize=320m"
#JAVA_OPT="${JAVA_OPT} -XX:+UseConcMarkSweepGC -XX:+UseCMSCompactAtFullCollection -XX:CMSInitiatingOccupancyFraction=70 -XX:+CMSParallelRemarkEnabled -XX:SoftRefLRUPolicyMSPerMB=0 -XX:+CMSClassUnloadingEnabled -XX:SurvivorRatio=8  -XX:-UseParNewGC"
JAVA_OPT="${JAVA_OPT} -XX:+UseConcMarkSweepGC -XX:CMSInitiatingOccupancyFraction=70 -XX:+CMSParallelRemarkEnabled -XX:SoftRefLRUPolicyMSPerMB=0 -XX:+CMSClassUnloadingEnabled -XX:SurvivorRatio=8 "
JAVA_OPT="${JAVA_OPT} -verbose:gc -Xloggc:/dev/shm/rmq_srv_gc.log -XX:+PrintGCDetails"
JAVA_OPT="${JAVA_OPT} -XX:-OmitStackTraceInFastThrow"
JAVA_OPT="${JAVA_OPT}  -XX:-UseLargePages"
#JAVA_OPT="${JAVA_OPT} -Djava.ext.dirs=${JAVA_HOME}/jre/lib/ext:${BASE_DIR}/lib"
#JAVA_OPT="${JAVA_OPT} -Djava.ext.dirs=${JAVA_HOME}/bin:${BASE_DIR}/lib"
JAVA_OPT="${JAVA_OPT} -Xdebug -Xrunjdwp:transport=dt_socket,address=9555,server=y,suspend=n"
JAVA_OPT="${JAVA_OPT} ${JAVA_OPT_EXT}"
JAVA_OPT="${JAVA_OPT} -cp ${CLASSPATH}"


$JAVA ${JAVA_OPT} $@

主要有三点：内存大小、java启动配置、classpath。
这样启动的时候就不会报如下错误啦

Error: Unable to initialize main class org.apache.rocketmq.namesrv.NamesrvStartup
Caused by: java.lang.NoClassDefFoundError: org/apache/rocketmq/srvutil/ShutdownHookThread

borker启动文件修改
vim runbroker.sh

error_exit ()
{   
    echo "ERROR: $1 !!"
    exit 1
}

[ ! -e "$JAVA_HOME/bin/java" ] && JAVA_HOME=$HOME/jdk/java
[ ! -e "$JAVA_HOME/bin/java" ] && JAVA_HOME=/usr/java
[ ! -e "$JAVA_HOME/bin/java" ] && error_exit "Please set the JAVA_HOME variable in your environment, We need java(x64)!"

export JAVA_HOME
export JAVA="$JAVA_HOME/bin/java"
export BASE_DIR=$(dirname $0)/..
#export CLASSPATH=.:${BASE_DIR}/conf:${CLASSPATH}
export CLASSPATH=${BASE_DIR}/lib/rocketmq-broker-4.4.0.jar:${BASE_DIR}/lib/*:${BASE_DIR}/conf:${CLASSPATH}
export CLASSPATH=${BASE_DIR}/lib/rocketmq-broker-4.4.0.jar:${BASE_DIR}/lib/*:${BASE_DIR}/conf/:.:${CLASSPATH}
#JAVA_OPT="${JAVA_OPT} -server -Xms8g -Xmx8g -Xmn4g"
JAVA_OPT="${JAVA_OPT} -server -Xms1g -Xmx1g -Xmn512m"
JAVA_OPT="${JAVA_OPT} -XX:+UseG1GC -XX:G1HeapRegionSize=16m -XX:G1ReservePercent=25 -XX:InitiatingHeapOccupancyPercent=30 -XX:SoftRefLRUPolicyMSPerMB=0"
JAVA_OPT="${JAVA_OPT} -verbose:gc -Xloggc:/dev/shm/mq_gc_%p.log -XX:+PrintGCDetails"
#JAVA_OPT="${JAVA_OPT} -XX:+UseGCLogFileRotation -XX:NumberOfGCLogFiles=5 -XX:GCLogFileSize=30m"
JAVA_OPT="${JAVA_OPT} -XX:-OmitStackTraceInFastThrow"
JAVA_OPT="${JAVA_OPT} -XX:+AlwaysPreTouch"
JAVA_OPT="${JAVA_OPT} -XX:MaxDirectMemorySize=15g"
JAVA_OPT="${JAVA_OPT} -XX:-UseLargePages -XX:-UseBiasedLocking"
#JAVA_OPT="${JAVA_OPT} -Djava.ext.dirs=${JAVA_HOME}/jre/lib/ext:${BASE_DIR}/lib"
#JAVA_OPT="${JAVA_OPT} -Xdebug -Xrunjdwp:transport=dt_socket,address=9555,server=y,suspend=n"
JAVA_OPT="${JAVA_OPT} ${JAVA_OPT_EXT}"
JAVA_OPT="${JAVA_OPT} -cp ${CLASSPATH}"

numactl --interleave=all pwd > /dev/null 2>&1
if [ $? -eq 0 ]
then
        if [ -z "$RMQ_NUMA_NODE" ] ; then
                numactl --interleave=all $JAVA ${JAVA_OPT} $@
        else
                numactl --cpunodebind=$RMQ_NUMA_NODE --membind=$RMQ_NUMA_NODE $JAVA ${JAVA_OPT} $@
        fi
else
        $JAVA ${JAVA_OPT} $@
fi

主要修改点与nameserver配置文件的修改点相似。
修改工具类脚本文件：
vim tools.sh

error_exit ()
{
    echo "ERROR: $1 !!"
    exit 1
}

[ ! -e "$JAVA_HOME/bin/java" ] && JAVA_HOME=$HOME/jdk/java
[ ! -e "$JAVA_HOME/bin/java" ] && JAVA_HOME=/usr/java
[ ! -e "$JAVA_HOME/bin/java" ] && error_exit "Please set the JAVA_HOME variable in your environment, We need java(x64)!"

export JAVA_HOME
export JAVA="$JAVA_HOME/bin/java"
export BASE_DIR=$(dirname $0)/..
export CLASSPATH=${BASE_DIR}/lib/*:${BASE_DIR}/conf:.:${CLASSPATH}

#===========================================================================================
# JVM Configuration
#===========================================================================================
JAVA_OPT="${JAVA_OPT} -server -Xms1g -Xmx1g -Xmn256m -XX:PermSize=128m -XX:MaxPermSize=128m"
#JAVA_OPT="${JAVA_OPT} -Djava.ext.dirs=${BASE_DIR}/lib:${JAVA_HOME}/jre/lib/ext"
JAVA_OPT="${JAVA_OPT} -cp ${CLASSPATH}"

$JAVA ${JAVA_OPT} $@