hadoop2.2.0 maprd-site.xml--Proxy Configuration

<!-- Proxy Configuration -->

<property>
  <name>mapreduce.jobtracker.taskcache.levels</name>
  <value>2</value>
  <description> This is the max level of the task cache. For example, if
    the level is 2, the tasks cached are at the host level and at the rack
    level.
  </description>
</property>

注释：

<property>
  <name>mapreduce.job.queuename</name>
  <value>default</value>
  <description> Queue to which a job is submitted. This must match one of the
    queues defined in mapred-queues.xml for the system. Also, the ACL setup
    for the queue must allow the current user to submit a job to the queue.
    Before specifying a queue, ensure that the system is configured with 
    the queue, and access is allowed for submitting jobs to the queue.
  </description>
</property>

注释：

<property>
  <name>mapreduce.cluster.acls.enabled</name>
  <value>false</value>
  <description> Specifies whether ACLs should be checked
    for authorization of users for doing various queue and job level operations.
    ACLs are disabled by default. If enabled, access control checks are made by
    JobTracker and TaskTracker when requests are made by users for queue
    operations like submit job to a queue and kill a job in the queue and job
    operations like viewing the job-details (See mapreduce.job.acl-view-job)
    or for modifying the job (See mapreduce.job.acl-modify-job) using
    Map/Reduce APIs, RPCs or via the console and web user interfaces.
    For enabling this flag(mapreduce.cluster.acls.enabled), this is to be set
    to true in mapred-site.xml on JobTracker node and on all TaskTracker nodes.
  </description>
</property>

注释：

<property>
  <name>mapreduce.job.acl-modify-job</name>
  <value> </value>
  <description> Job specific access-control list for 'modifying' the job. It
    is only used if authorization is enabled in Map/Reduce by setting the
    configuration property mapreduce.cluster.acls.enabled to true.
    This specifies the list of users and/or groups who can do modification
    operations on the job. For specifying a list of users and groups the
    format to use is "user1,user2 group1,group". If set to '*', it allows all
    users/groups to modify this job. If set to ' '(i.e. space), it allows
    none. This configuration is used to guard all the modifications with respect
    to this job and takes care of all the following operations:
      o killing this job
      o killing a task of this job, failing a task of this job
      o setting the priority of this job
    Each of these operations are also protected by the per-queue level ACL
    "acl-administer-jobs" configured via mapred-queues.xml. So a caller should
    have the authorization to satisfy either the queue-level ACL or the
    job-level ACL.

    Irrespective of this ACL configuration, (a) job-owner, (b) the user who
    started the cluster, (c) members of an admin configured supergroup
    configured via mapreduce.cluster.permissions.supergroup and (d) queue
    administrators of the queue to which this job was submitted to configured
    via acl-administer-jobs for the specific queue in mapred-queues.xml can
    do all the modification operations on a job.

    By default, nobody else besides job-owner, the user who started the cluster,
    members of supergroup and queue administrators can perform modification
    operations on a job.
  </description>
</property>

注释：

<property>
  <name>mapreduce.job.acl-view-job</name>
  <value> </value>
  <description> Job specific access-control list for 'viewing' the job. It is
    only used if authorization is enabled in Map/Reduce by setting the
    configuration property mapreduce.cluster.acls.enabled to true.
    This specifies the list of users and/or groups who can view private details
    about the job. For specifying a list of users and groups the
    format to use is "user1,user2 group1,group". If set to '*', it allows all
    users/groups to modify this job. If set to ' '(i.e. space), it allows
    none. This configuration is used to guard some of the job-views and at
    present only protects APIs that can return possibly sensitive information
    of the job-owner like
      o job-level counters
      o task-level counters
      o tasks' diagnostic information
      o task-logs displayed on the TaskTracker web-UI and
      o job.xml showed by the JobTracker's web-UI
    Every other piece of information of jobs is still accessible by any other
    user, for e.g., JobStatus, JobProfile, list of jobs in the queue, etc.

    Irrespective of this ACL configuration, (a) job-owner, (b) the user who
    started the cluster, (c) members of an admin configured supergroup
    configured via mapreduce.cluster.permissions.supergroup and (d) queue
    administrators of the queue to which this job was submitted to configured
    via acl-administer-jobs for the specific queue in mapred-queues.xml can
    do all the view operations on a job.

    By default, nobody else besides job-owner, the user who started the
    cluster, memebers of supergroup and queue administrators can perform
    view operations on a job.
  </description>
</property>

注释：

<property>
  <name>mapreduce.tasktracker.indexcache.mb</name>
  <value>10</value>
  <description> The maximum memory that a task tracker allows for the 
    index cache that is used when serving map outputs to reducers.
  </description>
</property>

注释：

<property>
  <name>mapreduce.task.merge.progress.records</name>
  <value>10000</value>
  <description> The number of records to process during merge before
   sending a progress notification to the TaskTracker.
  </description>
</property>

注释：

<property>
  <name>mapreduce.job.reduce.slowstart.completedmaps</name>
  <value>0.05</value>
  <description>Fraction of the number of maps in the job which should be 
  complete before reduces are scheduled for the job. 
  </description>
</property>

注释：

<property>
<name>mapreduce.job.complete.cancel.delegation.tokens</name>
  <value>true</value>
  <description> if false - do not unregister/cancel delegation tokens from 
    renewal, because same tokens may be used by spawned jobs
  </description>
</property>

注释：

<property>
  <name>mapreduce.tasktracker.taskcontroller</name>
  <value>org.apache.hadoop.mapred.DefaultTaskController</value>
  <description>TaskController which is used to launch and manage task execution 
  </description>
</property>

注释：

<property>
  <name>mapreduce.tasktracker.group</name>
  <value></value>
  <description>Expert: Group to which TaskTracker belongs. If 
   LinuxTaskController is configured via mapreduce.tasktracker.taskcontroller,
   the group owner of the task-controller binary should be same as this group.
  </description>
</property>

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