Hadoop启动脚本全解析，不能再全了！[bed]
转自:http://blog.csdn.net/mrtitan/article/details/9115621
在工作过程中，经常需要调整一些hadoop的参数配置，所以经常会遇到各种各样的问题。比如改了个配置怎么突然namenode起不来啦，加了个jar包怎么让hadoop的jvm加载啊，如何设定log目录啦等等，每次都需要仔细的查一遍启动脚本才能找到原因，费时又费力，因此专门总结了一下以便不时之需。
cloudera的hadoop的启动脚本写的异常复杂和零散，各种shell脚本分散在系统的各个角落，让人很无语。下面以namenode启动的过程为例说明hadoop的启动脚本的调用关系和各个脚本的作用。
hadoop启动的入口脚本是/etc/init.d/hadoop-hdfs-name，下面我们顺着启动namenode的顺序看看hadoop的启动调用过程。
/etc/init.d/hadoop-hdfs-namenode：
#1.加载/etc/default/hadoop /etc/default/hadoop-hdfs-namenode
#2.执行/usr/lib/hadoop/sbin/hadoop-daemon.sh启动namenode
cloudera启动namenode的用户为hdfs，默认的配置目录是/etc/hadoop/conf
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[*]start(){
[*][-x$EXEC_PATH]||exit$ERROR_PROGRAM_NOT_INSTALLED
[*][-d$CONF_DIR]||exit$ERROR_PROGRAM_NOT_CONFIGURED
[*]log_success_msg"Starting${DESC}:"
[*]
[*]su-s/bin/bash$SVC_USER-c"$EXEC_PATH--config'$CONF_DIR'start$DAEMON_FLAGS"
[*]
[*]#Someprocessesareslowtostart
[*]sleep$SLEEP_TIME
[*]checkstatusofproc
[*]RETVAL=$?
[*]
[*][$RETVAL-eq$RETVAL_SUCCESS]&&touch$LOCKFILE
[*]return$RETVAL
[*]}
start() {
[ -x $EXEC_PATH ] || exit $ERROR_PROGRAM_NOT_INSTALLED
[ -d $CONF_DIR ] || exit $ERROR_PROGRAM_NOT_CONFIGURED
log_success_msg "Starting ${DESC}: "
su -s /bin/bash $SVC_USER -c "$EXEC_PATH --config '$CONF_DIR' start $DAEMON_FLAGS"
# Some processes are slow to start
sleep $SLEEP_TIME
checkstatusofproc
RETVAL=$?
[ $RETVAL -eq $RETVAL_SUCCESS ] && touch $LOCKFILE
return $RETVAL
}
/etc/default/hadoop /etc/default/hadoop-hdfs-namenode：
#1.配置logdir，piddir，user
/usr/lib/hadoop/sbin/hadoop-daemon.sh
#1.加载/usr/lib/hadoop/libexec/hadoop-config.sh
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[*]DEFAULT_LIBEXEC_DIR="$bin"/../libexec
[*]HADOOP_LIBEXEC_DIR=${HADOOP_LIBEXEC_DIR:-$DEFAULT_LIBEXEC_DIR}
[*].$HADOOP_LIBEXEC_DIR/hadoop-config.sh
DEFAULT_LIBEXEC_DIR="$bin"/../libexec
HADOOP_LIBEXEC_DIR=${HADOOP_LIBEXEC_DIR:-$DEFAULT_LIBEXEC_DIR}
. $HADOOP_LIBEXEC_DIR/hadoop-config.sh
#2.加载hadoop-env.sh
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[*]if[-f"${HADOOP_CONF_DIR}/hadoop-env.sh"];then
[*]."${HADOOP_CONF_DIR}/hadoop-env.sh"
[*]fi
if [ -f "${HADOOP_CONF_DIR}/hadoop-env.sh" ]; then
. "${HADOOP_CONF_DIR}/hadoop-env.sh"
fi
#3.指定log目录
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[*]#getlogdirectory
[*]if["$HADOOP_LOG_DIR"=""];then
[*]exportHADOOP_LOG_DIR="$HADOOP_PREFIX/logs"
[*]fi
# get log directory
if [ "$HADOOP_LOG_DIR" = "" ]; then
export HADOOP_LOG_DIR="$HADOOP_PREFIX/logs"
fi
#4.补全log目录和log4j的logger等参数
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[*]exportHADOOP_LOGFILE=hadoop-$HADOOP_IDENT_STRING-$command-$HOSTNAME.log
[*]exportHADOOP_ROOT_LOGGER=${HADOOP_ROOT_LOGGER:-"INFO,RFA"}
[*]exportHADOOP_SECURITY_LOGGER=${HADOOP_SECURITY_LOGGER:-"INFO,RFAS"}
[*]exportHDFS_AUDIT_LOGGER=${HDFS_AUDIT_LOGGER:-"INFO,NullAppender"}
[*]log=$HADOOP_LOG_DIR/hadoop-$HADOOP_IDENT_STRING-$command-$HOSTNAME.out
[*]pid=$HADOOP_PID_DIR/hadoop-$HADOOP_IDENT_STRING-$command.pid
[*]HADOOP_STOP_TIMEOUT=${HADOOP_STOP_TIMEOUT:-5}
export HADOOP_LOGFILE=hadoop-$HADOOP_IDENT_STRING-$command-$HOSTNAME.log
export HADOOP_ROOT_LOGGER=${HADOOP_ROOT_LOGGER:-"INFO,RFA"}
export HADOOP_SECURITY_LOGGER=${HADOOP_SECURITY_LOGGER:-"INFO,RFAS"}
export HDFS_AUDIT_LOGGER=${HDFS_AUDIT_LOGGER:-"INFO,NullAppender"}
log=$HADOOP_LOG_DIR/hadoop-$HADOOP_IDENT_STRING-$command-$HOSTNAME.out
pid=$HADOOP_PID_DIR/hadoop-$HADOOP_IDENT_STRING-$command.pid
HADOOP_STOP_TIMEOUT=${HADOOP_STOP_TIMEOUT:-5}
#5.调用/usr/lib/hadoop-hdfs/bin/hdfs
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[*]hadoop_rotate_log$log
[*]echostarting$command,loggingto$log
[*]cd"$HADOOP_PREFIX"
[*]case$commandin
[*]namenode|secondarynamenode|datanode|journalnode|dfs|dfsadmin|fsck|balancer|zkfc)
[*]if[-z"$HADOOP_HDFS_HOME"];then
[*]hdfsScript="$HADOOP_PREFIX"/bin/hdfs
[*]else
[*]hdfsScript="$HADOOP_HDFS_HOME"/bin/hdfs
[*]fi
[*]nohupnice-n$HADOOP_NICENESS$hdfsScript--config$HADOOP_CONF_DIR$command"$@">"$log"2>&1</dev/null&
[*];;
[*](*)
[*]nohupnice-n$HADOOP_NICENESS$hadoopScript--config$HADOOP_CONF_DIR$command"$@">"$log"2>&1</dev/null&
[*];;
[*]esac
[*]echo$!>$pid
[*]sleep1;head"$log"
[*]sleep3;
[*]if!ps-p$!>/dev/null;then
[*]exit1
[*]fi
hadoop_rotate_log $log
echo starting $command, logging to $log
cd "$HADOOP_PREFIX"
case $command in
namenode|secondarynamenode|datanode|journalnode|dfs|dfsadmin|fsck|balancer|zkfc)
if [ -z "$HADOOP_HDFS_HOME" ]; then
hdfsScript="$HADOOP_PREFIX"/bin/hdfs
else
hdfsScript="$HADOOP_HDFS_HOME"/bin/hdfs
fi
nohup nice -n $HADOOP_NICENESS $hdfsScript --config $HADOOP_CONF_DIR $command "$@" > "$log" 2>&1 < /dev/null &
;;
(*)
nohup nice -n $HADOOP_NICENESS $hadoopScript --config $HADOOP_CONF_DIR $command "$@" > "$log" 2>&1 < /dev/null &
;;
esac
echo $! > $pid
sleep 1; head "$log"
sleep 3;
if ! ps -p $! > /dev/null ; then
exit 1
fi
可以看到namenode的sysout输出到$log中，即log=$HADOOP_LOG_DIR/hadoop-$HADOOP_IDENT_STRING-$command-$HOSTNAME.out
/usr/lib/hadoop/libexec/hadoop-config.sh
#1.加载/usr/lib/hadoop/libexec/hadoop-layout.sh
hadoop-layout.sh主要描述了hadoop的lib的文件夹结构，主要内容如下
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[*]HADOOP_COMMON_DIR="./"
[*]HADOOP_COMMON_LIB_JARS_DIR="lib"
[*]HADOOP_COMMON_LIB_NATIVE_DIR="lib/native"
[*]HDFS_DIR="./"
[*]HDFS_LIB_JARS_DIR="lib"
[*]YARN_DIR="./"
[*]YARN_LIB_JARS_DIR="lib"
[*]MAPRED_DIR="./"
[*]MAPRED_LIB_JARS_DIR="lib"
[*]
[*]HADOOP_LIBEXEC_DIR=${HADOOP_LIBEXEC_DIR:-"/usr/lib/hadoop/libexec"}
[*]HADOOP_CONF_DIR=${HADOOP_CONF_DIR:-"/etc/hadoop/conf"}
[*]HADOOP_COMMON_HOME=${HADOOP_COMMON_HOME:-"/usr/lib/hadoop"}
[*]HADOOP_HDFS_HOME=${HADOOP_HDFS_HOME:-"/usr/lib/hadoop-hdfs"}
[*]HADOOP_MAPRED_HOME=${HADOOP_MAPRED_HOME:-"/usr/lib/hadoop-0.20-mapreduce"}
[*]YARN_HOME=${YARN_HOME:-"/usr/lib/hadoop-yarn"}
HADOOP_COMMON_DIR="./"
HADOOP_COMMON_LIB_JARS_DIR="lib"
HADOOP_COMMON_LIB_NATIVE_DIR="lib/native"
HDFS_DIR="./"
HDFS_LIB_JARS_DIR="lib"
YARN_DIR="./"
YARN_LIB_JARS_DIR="lib"
MAPRED_DIR="./"
MAPRED_LIB_JARS_DIR="lib"
HADOOP_LIBEXEC_DIR=${HADOOP_LIBEXEC_DIR:-"/usr/lib/hadoop/libexec"}
HADOOP_CONF_DIR=${HADOOP_CONF_DIR:-"/etc/hadoop/conf"}
HADOOP_COMMON_HOME=${HADOOP_COMMON_HOME:-"/usr/lib/hadoop"}
HADOOP_HDFS_HOME=${HADOOP_HDFS_HOME:-"/usr/lib/hadoop-hdfs"}
HADOOP_MAPRED_HOME=${HADOOP_MAPRED_HOME:-"/usr/lib/hadoop-0.20-mapreduce"}
YARN_HOME=${YARN_HOME:-"/usr/lib/hadoop-yarn"}
#2.指定HDFS和YARN的lib
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[*]HADOOP_COMMON_DIR=${HADOOP_COMMON_DIR:-"share/hadoop/common"}
[*]HADOOP_COMMON_LIB_JARS_DIR=${HADOOP_COMMON_LIB_JARS_DIR:-"share/hadoop/common/lib"}
[*]HADOOP_COMMON_LIB_NATIVE_DIR=${HADOOP_COMMON_LIB_NATIVE_DIR:-"lib/native"}
[*]HDFS_DIR=${HDFS_DIR:-"share/hadoop/hdfs"}
[*]HDFS_LIB_JARS_DIR=${HDFS_LIB_JARS_DIR:-"share/hadoop/hdfs/lib"}
[*]YARN_DIR=${YARN_DIR:-"share/hadoop/yarn"}
[*]YARN_LIB_JARS_DIR=${YARN_LIB_JARS_DIR:-"share/hadoop/yarn/lib"}
[*]MAPRED_DIR=${MAPRED_DIR:-"share/hadoop/mapreduce"}
[*]MAPRED_LIB_JARS_DIR=${MAPRED_LIB_JARS_DIR:-"share/hadoop/mapreduce/lib"}
[*]
[*]#therootoftheHadoopinstallation
[*]#SeeHADOOP-6255fordirectorystructurelayout
[*]HADOOP_DEFAULT_PREFIX=$(cd-P--"$common_bin"/..&&pwd-P)
[*]HADOOP_PREFIX=${HADOOP_PREFIX:-$HADOOP_DEFAULT_PREFIX}
[*]exportHADOOP_PREFIX
HADOOP_COMMON_DIR=${HADOOP_COMMON_DIR:-"share/hadoop/common"}
HADOOP_COMMON_LIB_JARS_DIR=${HADOOP_COMMON_LIB_JARS_DIR:-"share/hadoop/common/lib"}
HADOOP_COMMON_LIB_NATIVE_DIR=${HADOOP_COMMON_LIB_NATIVE_DIR:-"lib/native"}
HDFS_DIR=${HDFS_DIR:-"share/hadoop/hdfs"}
HDFS_LIB_JARS_DIR=${HDFS_LIB_JARS_DIR:-"share/hadoop/hdfs/lib"}
YARN_DIR=${YARN_DIR:-"share/hadoop/yarn"}
YARN_LIB_JARS_DIR=${YARN_LIB_JARS_DIR:-"share/hadoop/yarn/lib"}
MAPRED_DIR=${MAPRED_DIR:-"share/hadoop/mapreduce"}
MAPRED_LIB_JARS_DIR=${MAPRED_LIB_JARS_DIR:-"share/hadoop/mapreduce/lib"}
# the root of the Hadoop installation
# See HADOOP-6255 for directory structure layout
HADOOP_DEFAULT_PREFIX=$(cd -P -- "$common_bin"/.. && pwd -P)
HADOOP_PREFIX=${HADOOP_PREFIX:-$HADOOP_DEFAULT_PREFIX}
export HADOOP_PREFIX
#3.对slave文件判断。但cdh的hadoop不是依靠slave来启动集群的，而是要用户自己写集群启动脚本（也许是为了逼用户用他的CloudManager。。。）
#4.再次指定env文件
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[*]if[-f"${HADOOP_CONF_DIR}/hadoop-env.sh"];then
[*]."${HADOOP_CONF_DIR}/hadoop-env.sh"
[*]fi
if [ -f "${HADOOP_CONF_DIR}/hadoop-env.sh" ]; then
. "${HADOOP_CONF_DIR}/hadoop-env.sh"
fi
#5.指定java home
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[*]#AttempttosetJAVA_HOMEifitisnotset
[*]if[[-z$JAVA_HOME]];then
[*]#OnOSXusejava_home(or/Libraryforolderversions)
[*]if["Darwin"=="$(uname-s)"];then
[*]if[-x/usr/libexec/java_home];then
[*]exportJAVA_HOME=($(/usr/libexec/java_home))
[*]else
[*]exportJAVA_HOME=(/Library/Java/Home)
[*]fi
[*]fi
[*]
[*]#Bailifwedidnotdetectit
[*]if[[-z$JAVA_HOME]];then
[*]echo"Error:JAVA_HOMEisnotsetandcouldnotbefound."1>&2
[*]exit1
[*]fi
[*]fi
# Attempt to set JAVA_HOME if it is not set
if [[ -z $JAVA_HOME ]]; then
# On OSX use java_home (or /Library for older versions)
if [ "Darwin" == "$(uname -s)" ]; then
if [ -x /usr/libexec/java_home ]; then
export JAVA_HOME=($(/usr/libexec/java_home))
else
export JAVA_HOME=(/Library/Java/Home)
fi
fi
# Bail if we did not detect it
if [[ -z $JAVA_HOME ]]; then
echo "Error: JAVA_HOME is not set and could not be found." 1>&2
exit 1
fi
fi
#6.指定Java程序启动的heapsize，如果用户在hadoop-env.sh中指定了HADOOP_HEAPSIZE字段则会覆盖默认值1000m
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[*]#someJavaparameters
[*]JAVA_HEAP_MAX=-Xmx1000m
[*]
[*]#checkenvvarswhichmightoverridedefaultargs
[*]if["$HADOOP_HEAPSIZE"!=""];then
[*]#echo"runwithheapsize$HADOOP_HEAPSIZE"
[*]JAVA_HEAP_MAX="-Xmx""$HADOOP_HEAPSIZE""m"
[*]#echo$JAVA_HEAP_MAX
[*]fi
# some Java parameters
JAVA_HEAP_MAX=-Xmx1000m
# check envvars which might override default args
if [ "$HADOOP_HEAPSIZE" != "" ]; then
#echo "run with heapsize $HADOOP_HEAPSIZE"
JAVA_HEAP_MAX="-Xmx""$HADOOP_HEAPSIZE""m"
#echo $JAVA_HEAP_MAX
fi
#7.指定程序的classpath，一大串代码，总结下就是
HADOOP_CONF_DIR+HADOOP_CLASSPATH+HADOOP_COMMON_DIR+HADOOP_COMMON_LIB_JARS_DIR+
HADOOP_COMMON_LIB_JARS_DIR+HADOOP_COMMON_LIB_NATIVE_DIR+HDFS_DIR+HDFS_LIB_JARS_DIR
+YARN_DIR+YARN_LIB_JARS_DIR+MAPRED_DIR+MAPRED_LIB_JARS_DIR
有一个要注意的，hadoop比较贴心的提供了HADOOP_USER_CLASSPATH_FIRST属性，如何设置了，
则HADOOP_CLASSPATH（用户自定义classpath）会在hadoop自身的jar包前加载，用来解决用户
想最先加载自定义的jar包情况。
#8.指定HADOOP_OPTS，-Dhadoop.log.dir这些类似参数会在conf下的log4j配置中用到
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[*]HADOOP_OPTS="$HADOOP_OPTS-Dhadoop.log.dir=$HADOOP_LOG_DIR"
[*]HADOOP_OPTS="$HADOOP_OPTS-Dhadoop.log.file=$HADOOP_LOGFILE"
[*]HADOOP_OPTS="$HADOOP_OPTS-Dhadoop.home.dir=$HADOOP_PREFIX"
[*]HADOOP_OPTS="$HADOOP_OPTS-Dhadoop.id.str=$HADOOP_IDENT_STRING"
[*]HADOOP_OPTS="$HADOOP_OPTS-Dhadoop.root.logger=${HADOOP_ROOT_LOGGER:-INFO,console}"
[*]if["x$JAVA_LIBRARY_PATH"!="x"];then
[*]HADOOP_OPTS="$HADOOP_OPTS-Djava.library.path=$JAVA_LIBRARY_PATH"
[*]exportLD_LIBRARY_PATH=$LD_LIBRARY_PATH:$JAVA_LIBRARY_PATH
[*]fi
[*]HADOOP_OPTS="$HADOOP_OPTS-Dhadoop.policy.file=$HADOOP_POLICYFILE"
[*]
[*]#Disableipv6asitcancauseissues
[*]HADOOP_OPTS="$HADOOP_OPTS-Djava.net.preferIPv4Stack=true"
[*]
[*]<SPANstyle="FONT-SIZE:18px">
[*]</SPAN>
HADOOP_OPTS="$HADOOP_OPTS -Dhadoop.log.dir=$HADOOP_LOG_DIR"
HADOOP_OPTS="$HADOOP_OPTS -Dhadoop.log.file=$HADOOP_LOGFILE"
HADOOP_OPTS="$HADOOP_OPTS -Dhadoop.home.dir=$HADOOP_PREFIX"
HADOOP_OPTS="$HADOOP_OPTS -Dhadoop.id.str=$HADOOP_IDENT_STRING"
HADOOP_OPTS="$HADOOP_OPTS -Dhadoop.root.logger=${HADOOP_ROOT_LOGGER:-INFO,console}"
if [ "x$JAVA_LIBRARY_PATH" != "x" ]; then
HADOOP_OPTS="$HADOOP_OPTS -Djava.library.path=$JAVA_LIBRARY_PATH"
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$JAVA_LIBRARY_PATH
fi
HADOOP_OPTS="$HADOOP_OPTS -Dhadoop.policy.file=$HADOOP_POLICYFILE"
# Disable ipv6 as it can cause issues
HADOOP_OPTS="$HADOOP_OPTS -Djava.net.preferIPv4Stack=true"
/usr/lib/hadoop-hdfs/bin/hdfs
#1.加载/usr/lib/hadoop/libexec/hdfs-config.sh，但好像没啥作用
#2.根据启动参数指定java的启动mainclass：
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[*]if["$COMMAND"="namenode"];then
[*]CLASS='org.apache.hadoop.hdfs.server.namenode.NameNode'
[*]HADOOP_OPTS="$HADOOP_OPTS$HADOOP_NAMENODE_OPTS"
[*]
if [ "$COMMAND" = "namenode" ] ; then
CLASS='org.apache.hadoop.hdfs.server.namenode.NameNode'
HADOOP_OPTS="$HADOOP_OPTS $HADOOP_NAMENODE_OPTS"
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[*]#3.启动Java程序
[*]exec"$JAVA"-Dproc_$COMMAND$JAVA_HEAP_MAX$HADOOP_OPTS$CLASS"$@"
#3.启动Java程序
exec "$JAVA" -Dproc_$COMMAND $JAVA_HEAP_MAX $HADOOP_OPTS $CLASS "$@"
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[*]
最后介绍几个配置的小例子。
1.如何指定hadoop的log目录：
从启动脚本中看几个配置的优先级排序是hadoop-env.sh>hadoop-config.sh>/etc/default/hadoop，因此我们如果想指定hadoop的log目录只需在hadoop-env.sh中添加一行：
export HADOOP_LOG_DIR=xxxxx
2.如何添加自己的jar包到hadoop中被namenode，datanode使用
export HADOOP_CLASSPATH=xxxxx
3.如何单独设定namenode的java heapsize。
比如想设置namenode10G，datanode1G，这个就有点意思了。如果直接指定HADOOP_HEAPSIZE那么此参数会作用于namenode,datanode，而单独在namenode的参数中指定也会有点小问题哦，不过基本是可以使用的。
总之，由于hadoop的启动脚本极其多而且琐碎，再加上hbase hive的启动脚本都是类似的结构，导致在添加修改一些配置时会产生很多莫名的问题，大家也可以在使用的过程中细细体会啦
在工作过程中，经常需要调整一些hadoop的参数配置，所以经常会遇到各种各样的问题。比如改了个配置怎么突然namenode起不来啦，加了个jar包怎么让hadoop的jvm加载啊，如何设定log目录啦等等，每次都需要仔细的查一遍启动脚本才能找到原因，费时又费力，因此专门总结了一下以便不时之需。
cloudera的hadoop的启动脚本写的异常复杂和零散，各种shell脚本分散在系统的各个角落，让人很无语。下面以namenode启动的过程为例说明hadoop的启动脚本的调用关系和各个脚本的作用。
hadoop启动的入口脚本是/etc/init.d/hadoop-hdfs-name，下面我们顺着启动namenode的顺序看看hadoop的启动调用过程。
/etc/init.d/hadoop-hdfs-namenode：
#1.加载/etc/default/hadoop /etc/default/hadoop-hdfs-namenode
#2.执行/usr/lib/hadoop/sbin/hadoop-daemon.sh启动namenode
cloudera启动namenode的用户为hdfs，默认的配置目录是/etc/hadoop/conf
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[*]start(){
[*][-x$EXEC_PATH]||exit$ERROR_PROGRAM_NOT_INSTALLED
[*][-d$CONF_DIR]||exit$ERROR_PROGRAM_NOT_CONFIGURED
[*]log_success_msg"Starting${DESC}:"
[*]
[*]su-s/bin/bash$SVC_USER-c"$EXEC_PATH--config'$CONF_DIR'start$DAEMON_FLAGS"
[*]
[*]#Someprocessesareslowtostart
[*]sleep$SLEEP_TIME
[*]checkstatusofproc
[*]RETVAL=$?
[*]
[*][$RETVAL-eq$RETVAL_SUCCESS]&&touch$LOCKFILE
[*]return$RETVAL
[*]}
start() {
[ -x $EXEC_PATH ] || exit $ERROR_PROGRAM_NOT_INSTALLED
[ -d $CONF_DIR ] || exit $ERROR_PROGRAM_NOT_CONFIGURED
log_success_msg "Starting ${DESC}: "
su -s /bin/bash $SVC_USER -c "$EXEC_PATH --config '$CONF_DIR' start $DAEMON_FLAGS"
# Some processes are slow to start
sleep $SLEEP_TIME
checkstatusofproc
RETVAL=$?
[ $RETVAL -eq $RETVAL_SUCCESS ] && touch $LOCKFILE
return $RETVAL
}
/etc/default/hadoop /etc/default/hadoop-hdfs-namenode：
#1.配置logdir，piddir，user
/usr/lib/hadoop/sbin/hadoop-daemon.sh
#1.加载/usr/lib/hadoop/libexec/hadoop-config.sh
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[*]DEFAULT_LIBEXEC_DIR="$bin"/../libexec
[*]HADOOP_LIBEXEC_DIR=${HADOOP_LIBEXEC_DIR:-$DEFAULT_LIBEXEC_DIR}
[*].$HADOOP_LIBEXEC_DIR/hadoop-config.sh
DEFAULT_LIBEXEC_DIR="$bin"/../libexec
HADOOP_LIBEXEC_DIR=${HADOOP_LIBEXEC_DIR:-$DEFAULT_LIBEXEC_DIR}
. $HADOOP_LIBEXEC_DIR/hadoop-config.sh
#2.加载hadoop-env.sh
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[*]if[-f"${HADOOP_CONF_DIR}/hadoop-env.sh"];then
[*]."${HADOOP_CONF_DIR}/hadoop-env.sh"
[*]fi
if [ -f "${HADOOP_CONF_DIR}/hadoop-env.sh" ]; then
. "${HADOOP_CONF_DIR}/hadoop-env.sh"
fi
#3.指定log目录
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[*]#getlogdirectory
[*]if["$HADOOP_LOG_DIR"=""];then
[*]exportHADOOP_LOG_DIR="$HADOOP_PREFIX/logs"
[*]fi
# get log directory
if [ "$HADOOP_LOG_DIR" = "" ]; then
export HADOOP_LOG_DIR="$HADOOP_PREFIX/logs"
fi
#4.补全log目录和log4j的logger等参数
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[*]exportHADOOP_LOGFILE=hadoop-$HADOOP_IDENT_STRING-$command-$HOSTNAME.log
[*]exportHADOOP_ROOT_LOGGER=${HADOOP_ROOT_LOGGER:-"INFO,RFA"}
[*]exportHADOOP_SECURITY_LOGGER=${HADOOP_SECURITY_LOGGER:-"INFO,RFAS"}
[*]exportHDFS_AUDIT_LOGGER=${HDFS_AUDIT_LOGGER:-"INFO,NullAppender"}
[*]log=$HADOOP_LOG_DIR/hadoop-$HADOOP_IDENT_STRING-$command-$HOSTNAME.out
[*]pid=$HADOOP_PID_DIR/hadoop-$HADOOP_IDENT_STRING-$command.pid
[*]HADOOP_STOP_TIMEOUT=${HADOOP_STOP_TIMEOUT:-5}
export HADOOP_LOGFILE=hadoop-$HADOOP_IDENT_STRING-$command-$HOSTNAME.log
export HADOOP_ROOT_LOGGER=${HADOOP_ROOT_LOGGER:-"INFO,RFA"}
export HADOOP_SECURITY_LOGGER=${HADOOP_SECURITY_LOGGER:-"INFO,RFAS"}
export HDFS_AUDIT_LOGGER=${HDFS_AUDIT_LOGGER:-"INFO,NullAppender"}
log=$HADOOP_LOG_DIR/hadoop-$HADOOP_IDENT_STRING-$command-$HOSTNAME.out
pid=$HADOOP_PID_DIR/hadoop-$HADOOP_IDENT_STRING-$command.pid
HADOOP_STOP_TIMEOUT=${HADOOP_STOP_TIMEOUT:-5}
#5.调用/usr/lib/hadoop-hdfs/bin/hdfs
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[*]hadoop_rotate_log$log
[*]echostarting$command,loggingto$log
[*]cd"$HADOOP_PREFIX"
[*]case$commandin
[*]namenode|secondarynamenode|datanode|journalnode|dfs|dfsadmin|fsck|balancer|zkfc)
[*]if[-z"$HADOOP_HDFS_HOME"];then
[*]hdfsScript="$HADOOP_PREFIX"/bin/hdfs
[*]else
[*]hdfsScript="$HADOOP_HDFS_HOME"/bin/hdfs
[*]fi
[*]nohupnice-n$HADOOP_NICENESS$hdfsScript--config$HADOOP_CONF_DIR$command"$@">"$log"2>&1</dev/null&
[*];;
[*](*)
[*]nohupnice-n$HADOOP_NICENESS$hadoopScript--config$HADOOP_CONF_DIR$command"$@">"$log"2>&1</dev/null&
[*];;
[*]esac
[*]echo$!>$pid
[*]sleep1;head"$log"
[*]sleep3;
[*]if!ps-p$!>/dev/null;then
[*]exit1
[*]fi
hadoop_rotate_log $log
echo starting $command, logging to $log
cd "$HADOOP_PREFIX"
case $command in
namenode|secondarynamenode|datanode|journalnode|dfs|dfsadmin|fsck|balancer|zkfc)
if [ -z "$HADOOP_HDFS_HOME" ]; then
hdfsScript="$HADOOP_PREFIX"/bin/hdfs
else
hdfsScript="$HADOOP_HDFS_HOME"/bin/hdfs
fi
nohup nice -n $HADOOP_NICENESS $hdfsScript --config $HADOOP_CONF_DIR $command "$@" > "$log" 2>&1 < /dev/null &
;;
(*)
nohup nice -n $HADOOP_NICENESS $hadoopScript --config $HADOOP_CONF_DIR $command "$@" > "$log" 2>&1 < /dev/null &
;;
esac
echo $! > $pid
sleep 1; head "$log"
sleep 3;
if ! ps -p $! > /dev/null ; then
exit 1
fi
可以看到namenode的sysout输出到$log中，即log=$HADOOP_LOG_DIR/hadoop-$HADOOP_IDENT_STRING-$command-$HOSTNAME.out
/usr/lib/hadoop/libexec/hadoop-config.sh
#1.加载/usr/lib/hadoop/libexec/hadoop-layout.sh
hadoop-layout.sh主要描述了hadoop的lib的文件夹结构，主要内容如下
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[*]HADOOP_COMMON_DIR="./"
[*]HADOOP_COMMON_LIB_JARS_DIR="lib"
[*]HADOOP_COMMON_LIB_NATIVE_DIR="lib/native"
[*]HDFS_DIR="./"
[*]HDFS_LIB_JARS_DIR="lib"
[*]YARN_DIR="./"
[*]YARN_LIB_JARS_DIR="lib"
[*]MAPRED_DIR="./"
[*]MAPRED_LIB_JARS_DIR="lib"
[*]
[*]HADOOP_LIBEXEC_DIR=${HADOOP_LIBEXEC_DIR:-"/usr/lib/hadoop/libexec"}
[*]HADOOP_CONF_DIR=${HADOOP_CONF_DIR:-"/etc/hadoop/conf"}
[*]HADOOP_COMMON_HOME=${HADOOP_COMMON_HOME:-"/usr/lib/hadoop"}
[*]HADOOP_HDFS_HOME=${HADOOP_HDFS_HOME:-"/usr/lib/hadoop-hdfs"}
[*]HADOOP_MAPRED_HOME=${HADOOP_MAPRED_HOME:-"/usr/lib/hadoop-0.20-mapreduce"}
[*]YARN_HOME=${YARN_HOME:-"/usr/lib/hadoop-yarn"}
HADOOP_COMMON_DIR="./"
HADOOP_COMMON_LIB_JARS_DIR="lib"
HADOOP_COMMON_LIB_NATIVE_DIR="lib/native"
HDFS_DIR="./"
HDFS_LIB_JARS_DIR="lib"
YARN_DIR="./"
YARN_LIB_JARS_DIR="lib"
MAPRED_DIR="./"
MAPRED_LIB_JARS_DIR="lib"
HADOOP_LIBEXEC_DIR=${HADOOP_LIBEXEC_DIR:-"/usr/lib/hadoop/libexec"}
HADOOP_CONF_DIR=${HADOOP_CONF_DIR:-"/etc/hadoop/conf"}
HADOOP_COMMON_HOME=${HADOOP_COMMON_HOME:-"/usr/lib/hadoop"}
HADOOP_HDFS_HOME=${HADOOP_HDFS_HOME:-"/usr/lib/hadoop-hdfs"}
HADOOP_MAPRED_HOME=${HADOOP_MAPRED_HOME:-"/usr/lib/hadoop-0.20-mapreduce"}
YARN_HOME=${YARN_HOME:-"/usr/lib/hadoop-yarn"}
#2.指定HDFS和YARN的lib
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[*]HADOOP_COMMON_DIR=${HADOOP_COMMON_DIR:-"share/hadoop/common"}
[*]HADOOP_COMMON_LIB_JARS_DIR=${HADOOP_COMMON_LIB_JARS_DIR:-"share/hadoop/common/lib"}
[*]HADOOP_COMMON_LIB_NATIVE_DIR=${HADOOP_COMMON_LIB_NATIVE_DIR:-"lib/native"}
[*]HDFS_DIR=${HDFS_DIR:-"share/hadoop/hdfs"}
[*]HDFS_LIB_JARS_DIR=${HDFS_LIB_JARS_DIR:-"share/hadoop/hdfs/lib"}
[*]YARN_DIR=${YARN_DIR:-"share/hadoop/yarn"}
[*]YARN_LIB_JARS_DIR=${YARN_LIB_JARS_DIR:-"share/hadoop/yarn/lib"}
[*]MAPRED_DIR=${MAPRED_DIR:-"share/hadoop/mapreduce"}
[*]MAPRED_LIB_JARS_DIR=${MAPRED_LIB_JARS_DIR:-"share/hadoop/mapreduce/lib"}
[*]
[*]#therootoftheHadoopinstallation
[*]#SeeHADOOP-6255fordirectorystructurelayout
[*]HADOOP_DEFAULT_PREFIX=$(cd-P--"$common_bin"/..&&pwd-P)
[*]HADOOP_PREFIX=${HADOOP_PREFIX:-$HADOOP_DEFAULT_PREFIX}
[*]exportHADOOP_PREFIX
HADOOP_COMMON_DIR=${HADOOP_COMMON_DIR:-"share/hadoop/common"}
HADOOP_COMMON_LIB_JARS_DIR=${HADOOP_COMMON_LIB_JARS_DIR:-"share/hadoop/common/lib"}
HADOOP_COMMON_LIB_NATIVE_DIR=${HADOOP_COMMON_LIB_NATIVE_DIR:-"lib/native"}
HDFS_DIR=${HDFS_DIR:-"share/hadoop/hdfs"}
HDFS_LIB_JARS_DIR=${HDFS_LIB_JARS_DIR:-"share/hadoop/hdfs/lib"}
YARN_DIR=${YARN_DIR:-"share/hadoop/yarn"}
YARN_LIB_JARS_DIR=${YARN_LIB_JARS_DIR:-"share/hadoop/yarn/lib"}
MAPRED_DIR=${MAPRED_DIR:-"share/hadoop/mapreduce"}
MAPRED_LIB_JARS_DIR=${MAPRED_LIB_JARS_DIR:-"share/hadoop/mapreduce/lib"}
# the root of the Hadoop installation
# See HADOOP-6255 for directory structure layout
HADOOP_DEFAULT_PREFIX=$(cd -P -- "$common_bin"/.. && pwd -P)
HADOOP_PREFIX=${HADOOP_PREFIX:-$HADOOP_DEFAULT_PREFIX}
export HADOOP_PREFIX
#3.对slave文件判断。但cdh的hadoop不是依靠slave来启动集群的，而是要用户自己写集群启动脚本（也许是为了逼用户用他的CloudManager。。。）
#4.再次指定env文件
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[*]if[-f"${HADOOP_CONF_DIR}/hadoop-env.sh"];then
[*]."${HADOOP_CONF_DIR}/hadoop-env.sh"
[*]fi
if [ -f "${HADOOP_CONF_DIR}/hadoop-env.sh" ]; then
. "${HADOOP_CONF_DIR}/hadoop-env.sh"
fi
#5.指定java home
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[*]#AttempttosetJAVA_HOMEifitisnotset
[*]if[[-z$JAVA_HOME]];then
[*]#OnOSXusejava_home(or/Libraryforolderversions)
[*]if["Darwin"=="$(uname-s)"];then
[*]if[-x/usr/libexec/java_home];then
[*]exportJAVA_HOME=($(/usr/libexec/java_home))
[*]else
[*]exportJAVA_HOME=(/Library/Java/Home)
[*]fi
[*]fi
[*]
[*]#Bailifwedidnotdetectit
[*]if[[-z$JAVA_HOME]];then
[*]echo"Error:JAVA_HOMEisnotsetandcouldnotbefound."1>&2
[*]exit1
[*]fi
[*]fi
# Attempt to set JAVA_HOME if it is not set
if [[ -z $JAVA_HOME ]]; then
# On OSX use java_home (or /Library for older versions)
if [ "Darwin" == "$(uname -s)" ]; then
if [ -x /usr/libexec/java_home ]; then
export JAVA_HOME=($(/usr/libexec/java_home))
else
export JAVA_HOME=(/Library/Java/Home)
fi
fi
# Bail if we did not detect it
if [[ -z $JAVA_HOME ]]; then
echo "Error: JAVA_HOME is not set and could not be found." 1>&2
exit 1
fi
fi
#6.指定Java程序启动的heapsize，如果用户在hadoop-env.sh中指定了HADOOP_HEAPSIZE字段则会覆盖默认值1000m
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[*]#someJavaparameters
[*]JAVA_HEAP_MAX=-Xmx1000m
[*]
[*]#checkenvvarswhichmightoverridedefaultargs
[*]if["$HADOOP_HEAPSIZE"!=""];then
[*]#echo"runwithheapsize$HADOOP_HEAPSIZE"
[*]JAVA_HEAP_MAX="-Xmx""$HADOOP_HEAPSIZE""m"
[*]#echo$JAVA_HEAP_MAX
[*]fi
# some Java parameters
JAVA_HEAP_MAX=-Xmx1000m
# check envvars which might override default args
if [ "$HADOOP_HEAPSIZE" != "" ]; then
#echo "run with heapsize $HADOOP_HEAPSIZE"
JAVA_HEAP_MAX="-Xmx""$HADOOP_HEAPSIZE""m"
#echo $JAVA_HEAP_MAX
fi
#7.指定程序的classpath，一大串代码，总结下就是
HADOOP_CONF_DIR+HADOOP_CLASSPATH+HADOOP_COMMON_DIR+HADOOP_COMMON_LIB_JARS_DIR+
HADOOP_COMMON_LIB_JARS_DIR+HADOOP_COMMON_LIB_NATIVE_DIR+HDFS_DIR+HDFS_LIB_JARS_DIR
+YARN_DIR+YARN_LIB_JARS_DIR+MAPRED_DIR+MAPRED_LIB_JARS_DIR
有一个要注意的，hadoop比较贴心的提供了HADOOP_USER_CLASSPATH_FIRST属性，如何设置了，
则HADOOP_CLASSPATH（用户自定义classpath）会在hadoop自身的jar包前加载，用来解决用户
想最先加载自定义的jar包情况。
#8.指定HADOOP_OPTS，-Dhadoop.log.dir这些类似参数会在conf下的log4j配置中用到
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[*]HADOOP_OPTS="$HADOOP_OPTS-Dhadoop.log.dir=$HADOOP_LOG_DIR"
[*]HADOOP_OPTS="$HADOOP_OPTS-Dhadoop.log.file=$HADOOP_LOGFILE"
[*]HADOOP_OPTS="$HADOOP_OPTS-Dhadoop.home.dir=$HADOOP_PREFIX"
[*]HADOOP_OPTS="$HADOOP_OPTS-Dhadoop.id.str=$HADOOP_IDENT_STRING"
[*]HADOOP_OPTS="$HADOOP_OPTS-Dhadoop.root.logger=${HADOOP_ROOT_LOGGER:-INFO,console}"
[*]if["x$JAVA_LIBRARY_PATH"!="x"];then
[*]HADOOP_OPTS="$HADOOP_OPTS-Djava.library.path=$JAVA_LIBRARY_PATH"
[*]exportLD_LIBRARY_PATH=$LD_LIBRARY_PATH:$JAVA_LIBRARY_PATH
[*]fi
[*]HADOOP_OPTS="$HADOOP_OPTS-Dhadoop.policy.file=$HADOOP_POLICYFILE"
[*]
[*]#Disableipv6asitcancauseissues
[*]HADOOP_OPTS="$HADOOP_OPTS-Djava.net.preferIPv4Stack=true"
[*]
[*]<SPANstyle="FONT-SIZE:18px">
[*]</SPAN>
HADOOP_OPTS="$HADOOP_OPTS -Dhadoop.log.dir=$HADOOP_LOG_DIR"
HADOOP_OPTS="$HADOOP_OPTS -Dhadoop.log.file=$HADOOP_LOGFILE"
HADOOP_OPTS="$HADOOP_OPTS -Dhadoop.home.dir=$HADOOP_PREFIX"
HADOOP_OPTS="$HADOOP_OPTS -Dhadoop.id.str=$HADOOP_IDENT_STRING"
HADOOP_OPTS="$HADOOP_OPTS -Dhadoop.root.logger=${HADOOP_ROOT_LOGGER:-INFO,console}"
if [ "x$JAVA_LIBRARY_PATH" != "x" ]; then
HADOOP_OPTS="$HADOOP_OPTS -Djava.library.path=$JAVA_LIBRARY_PATH"
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$JAVA_LIBRARY_PATH
fi
HADOOP_OPTS="$HADOOP_OPTS -Dhadoop.policy.file=$HADOOP_POLICYFILE"
# Disable ipv6 as it can cause issues
HADOOP_OPTS="$HADOOP_OPTS -Djava.net.preferIPv4Stack=true"
/usr/lib/hadoop-hdfs/bin/hdfs
#1.加载/usr/lib/hadoop/libexec/hdfs-config.sh，但好像没啥作用
#2.根据启动参数指定java的启动mainclass：
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[*]if["$COMMAND"="namenode"];then
[*]CLASS='org.apache.hadoop.hdfs.server.namenode.NameNode'
[*]HADOOP_OPTS="$HADOOP_OPTS$HADOOP_NAMENODE_OPTS"
[*]
if [ "$COMMAND" = "namenode" ] ; then
CLASS='org.apache.hadoop.hdfs.server.namenode.NameNode'
HADOOP_OPTS="$HADOOP_OPTS $HADOOP_NAMENODE_OPTS"
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[*]#3.启动Java程序
[*]exec"$JAVA"-Dproc_$COMMAND$JAVA_HEAP_MAX$HADOOP_OPTS$CLASS"$@"
#3.启动Java程序
exec "$JAVA" -Dproc_$COMMAND $JAVA_HEAP_MAX $HADOOP_OPTS $CLASS "$@"
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[*]
最后介绍几个配置的小例子。
1.如何指定hadoop的log目录：
从启动脚本中看几个配置的优先级排序是hadoop-env.sh>hadoop-config.sh>/etc/default/hadoop，因此我们如果想指定hadoop的log目录只需在hadoop-env.sh中添加一行：
export HADOOP_LOG_DIR=xxxxx
2.如何添加自己的jar包到hadoop中被namenode，datanode使用
export HADOOP_CLASSPATH=xxxxx
3.如何单独设定namenode的java heapsize。
比如想设置namenode10G，datanode1G，这个就有点意思了。如果直接指定HADOOP_HEAPSIZE那么此参数会作用于namenode,datanode，而单独在namenode的参数中指定也会有点小问题哦，不过基本是可以使用的。
总之，由于hadoop的启动脚本极其多而且琐碎，再加上hbase hive的启动脚本都是类似的结构，导致在添加修改一些配置时会产生很多莫名的问题，大家也可以在使用的过程中细细体会啦
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