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  • Hadoop-env.sh[翻译]

    说明: 某天 ,把hadoop-env。sh的注释看了看 , 感觉受益匪浅,于是想要写一篇告诉大家,文档是最靠谱的,鉴于我的水平有限,只能翻译大概,切勿吐槽,提建议请留言

    摘要:

    1.这个文件中只有JAVA_HOME是必须要写的,其他的都是有默认值的PS 这个变量最好写地址, 而不要写${JAVA_HOME}

    # Set Hadoop-specific environment variables here.

    在这个文件中设置hadoop特有的环境变量

    # The only required environment variable is JAVA_HOME.  All others are
    # optional.  When running a distributed configuration it is best to
    # set JAVA_HOME in this file, so that it is correctly defined on
    # remote nodes.

    这里只要求JAVA_HOME的环境变量 , 其他的都是可选的。正确运行这个分布式的配置文件时,

    最好在这个文件里面设置JAVA_HOME ,所以在远程的节点中也要正确的定义它

    # The java implementation to use.  Required.
    # export JAVA_HOME=/usr/lib/j2sdk1.5-sun

    使用一个符合java的 , 这是必须要求的。

    export JAVA_HOME=“《写入你的JDK所在位置》”

    # Extra Java CLASSPATH elements.  Optional. 额外的java的alsspath元素 ,这个是可选的
    # export HADOOP_CLASSPATH=

    # The maximum amount of heap to use, in MB. Default is 1000. Heap区使用的大小,默认是1000M
    # export HADOOP_HEAPSIZE=2000

    # Extra Java runtime options.  Empty by default. java的运行选项,有默认值
    # export HADOOP_OPTS=-server

    # Command specific options appended to HADOOP_OPTS when specified以下指定的选项追加到HADOOP_OPTS中
    export HADOOP_NAMENODE_OPTS="-Dcom.sun.management.jmxremote $HADOOP_NAMENODE_OPTS"
    export HADOOP_SECONDARYNAMENODE_OPTS="-Dcom.sun.management.jmxremote $HADOOP_SECONDARYNAMENODE_OPTS"
    export HADOOP_DATANODE_OPTS="-Dcom.sun.management.jmxremote $HADOOP_DATANODE_OPTS"
    export HADOOP_BALANCER_OPTS="-Dcom.sun.management.jmxremote $HADOOP_BALANCER_OPTS"
    export HADOOP_JOBTRACKER_OPTS="-Dcom.sun.management.jmxremote $HADOOP_JOBTRACKER_OPTS"
    # export HADOOP_TASKTRACKER_OPTS=
    # The following applies to multiple commands (fs, dfs, fsck, distcp etc)
    # export HADOOP_CLIENT_OPTS

    # Extra ssh options.  Empty by default.SSH的选项,有默认值 
    # export HADOOP_SSH_OPTS="-o ConnectTimeout=1 -o SendEnv=HADOOP_CONF_DIR"

    # Where log files are stored.  $HADOOP_HOME/logs by default. 指明日志放在哪里,$HADOOP_HOME/logs 是默认值
    # export HADOOP_LOG_DIR=${HADOOP_HOME}/logs

    # File naming remote slave hosts.  $HADOOP_HOME/conf/slaves by default.指定从哪个 远程的从节点的主机名, $HADOOP_HOME/conf/slaves 是默认读取的文件
    # export HADOOP_SLAVES=${HADOOP_HOME}/conf/slaves

    # host:path where hadoop code should be rsync'd from.  Unset by default.
    # export HADOOP_MASTER=master:/home/$USER/src/hadoop

    # Seconds to sleep between slave commands.  Unset by default.  This
    # can be useful in large clusters, where, e.g., slave rsyncs can
    # otherwise arrive faster than the master can service them.
    # export HADOOP_SLAVE_SLEEP=0.1

    在salve命令中 , 没有设置的话使用默认值。 这个在大型的集群里面很有用

    # The directory where pid files are stored. /tmp by default.
    # NOTE: this should be set to a directory that can only be written to by
    #       the users that are going to run the hadoop daemons.  Otherwise there is
    #       the potential for a symlink attack.
    # export HADOOP_PID_DIR=/var/hadoop/pids

    指定PID文件放在那里 。默认是/tmp by default.

    注意:应该设置一个用户可以在hadoop运行的守护进程 , 否则会有潜在的符号链接的攻击

    # A string representing this instance of hadoop. $USER by default. 一个代表hadoop实例的字符串 , 默认是$USER

    # export HADOOP_IDENT_STRING=$USER

    # The scheduling priority for daemon processes.  See 'man nice'.  一个为守护进程调节优先级的进程
    # export HADOOP_NICENESS=10
    export JAVA_HOME=/usr/java/jdk1.7.0_76

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  • 原文地址:https://www.cnblogs.com/greentomlee/p/4481636.html
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