mapred-site.xml 默认参数

<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>

<!-- Do not modify this file directly.  Instead, copy entries that you -->
<!-- wish to modify from this file into mapred-site.xml and change them -->
<!-- there.  If mapred-site.xml does not already exist, create it.      -->

<configuration>

<property>
  <name>hadoop.job.history.location</name>
  <value></value>
  <description> If job tracker is static the history files are stored
  in this single well known place. If No value is set here, by default,
  it is in the local file system at ${hadoop.log.dir}/history.
  </description>
</property>

<property>
  <name>hadoop.job.history.user.location</name>
  <value></value>
  <description> User can specify a location to store the history files of
  a particular job. If nothing is specified, the logs are stored in
  output directory. The files are stored in "_logs/history/" in the directory.
  User can stop logging by giving the value "none".
  </description>
</property>

<property>
  <name>mapred.job.tracker.history.completed.location</name>
  <value></value>
  <description> The completed job history files are stored at this single well
  known location. If nothing is specified, the files are stored at
  ${hadoop.job.history.location}/done.
  </description>
</property>

<!-- i/o properties -->

<property>
  <name>io.sort.factor</name>
  <value>10</value>
  <description>The number of streams to merge at once while sorting
  files.  This determines the number of open file handles.</description>
</property>

<property>
  <name>io.sort.mb</name>
  <value>100</value>
  <description>The total amount of buffer memory to use while sorting
  files, in megabytes.  By default, gives each merge stream 1MB, which
  should minimize seeks.</description>
</property>

<property>
  <name>io.sort.record.percent</name>
  <value>0.05</value>
  <description>The percentage of io.sort.mb dedicated to tracking record
  boundaries. Let this value be r, io.sort.mb be x. The maximum number
  of records collected before the collection thread must block is equal
  to (r * x) / 4</description>
</property>

<property>
  <name>io.sort.spill.percent</name>
  <value>0.80</value>
  <description>The soft limit in either the buffer or record collection
  buffers. Once reached, a thread will begin to spill the contents to disk
  in the background. Note that this does not imply any chunking of data to
  the spill. A value less than 0.5 is not recommended.</description>
</property>

<property>
  <name>io.map.index.skip</name>
  <value>0</value>
  <description>Number of index entries to skip between each entry.
  Zero by default. Setting this to values larger than zero can
  facilitate opening large map files using less memory.</description>
</property>

<property>
  <name>mapred.job.tracker</name>
  <value>local</value>
  <description>The host and port that the MapReduce job tracker runs
  at.  If "local", then jobs are run in-process as a single map
  and reduce task.
  </description>
</property>

<property>
  <name>mapred.job.tracker.http.address</name>
  <value>0.0.0.0:50030</value>
  <description>
    The job tracker http server address and port the server will listen on.
    If the port is 0 then the server will start on a free port.
  </description>
</property>

<property>
  <name>mapred.job.tracker.handler.count</name>
  <value>10</value>
  <description>
    The number of server threads for the JobTracker. This should be roughly
    4% of the number of tasktracker nodes.
  </description>
</property>

<property>
  <name>mapred.task.tracker.report.address</name>
  <value>127.0.0.1:0</value>
  <description>The interface and port that task tracker server listens on.
  Since it is only connected to by the tasks, it uses the local interface.
  EXPERT ONLY. Should only be changed if your host does not have the loopback
  interface.</description>
</property>

<property>
  <name>mapred.local.dir</name>
  <value>${hadoop.tmp.dir}/mapred/local</value>
  <description>The local directory where MapReduce stores intermediate
  data files.  May be a comma-separated list of
  directories on different devices in order to spread disk i/o.
  Directories that do not exist are ignored.
  </description>
</property>

<property>
  <name>mapred.system.dir</name>
  <value>${hadoop.tmp.dir}/mapred/system</value>
  <description>The directory where MapReduce stores control files.
  </description>
</property>

<property>
  <name>mapreduce.jobtracker.staging.root.dir</name>
  <value>${hadoop.tmp.dir}/mapred/staging</value>
  <description>The root of the staging area for users' job files
  In practice, this should be the directory where users' home
  directories are located (usually /user)
  </description>
</property>

<property>
  <name>mapred.temp.dir</name>
  <value>${hadoop.tmp.dir}/mapred/temp</value>
  <description>A shared directory for temporary files.
  </description>
</property>

<property>
  <name>mapred.local.dir.minspacestart</name>
  <value>0</value>
  <description>If the space in mapred.local.dir drops under this,
  do not ask for more tasks.
  Value in bytes.
  </description>
</property>

<property>
  <name>mapred.local.dir.minspacekill</name>
  <value>0</value>
  <description>If the space in mapred.local.dir drops under this,
    do not ask more tasks until all the current ones have finished and
    cleaned up. Also, to save the rest of the tasks we have running,
    kill one of them, to clean up some space. Start with the reduce tasks,
    then go with the ones that have finished the least.
    Value in bytes.
  </description>
</property>

<property>
  <name>mapred.tasktracker.expiry.interval</name>
  <value>600000</value>
  <description>Expert: The time-interval, in miliseconds, after which
  a tasktracker is declared 'lost' if it doesn't send heartbeats.
  </description>
</property>

<!--
<property>
  <name>mapred.tasktracker.instrumentation</name>
  <value>com.example.hadoop.TaskTrackerInstrumentation</value>
  <description>Expert: The instrumentation class to associate with each TaskTracker.
  </description>
</property>
-->

<property>
  <name>mapred.tasktracker.resourcecalculatorplugin</name>
  <value></value>
  <description>
   Name of the class whose instance will be used to query resource information
   on the tasktracker.
  
   The class must be an instance of
   org.apache.hadoop.util.ResourceCalculatorPlugin. If the value is null, the
   tasktracker attempts to use a class appropriate to the platform.
   Currently, the only platform supported is Linux.
  </description>
</property>

<property>
  <name>mapred.tasktracker.taskmemorymanager.monitoring-interval</name>
  <value>5000</value>
  <description>The interval, in milliseconds, for which the tasktracker waits
   between two cycles of monitoring its tasks' memory usage. Used only if
   tasks' memory management is enabled via mapred.tasktracker.tasks.maxmemory.
   </description>
</property>

<property>
  <name>mapred.tasktracker.tasks.sleeptime-before-sigkill</name>
  <value>5000</value>
  <description>The time, in milliseconds, the tasktracker waits for sending a
  SIGKILL to a process, after it has been sent a SIGTERM.</description>
</property>

<property>
  <name>mapred.map.tasks</name>
  <value>2</value>
  <description>The default number of map tasks per job.
  Ignored when mapred.job.tracker is "local". 
  </description>
</property>

<property>
  <name>mapred.reduce.tasks</name>
  <value>1</value>
  <description>The default number of reduce tasks per job. Typically set to 99%
  of the cluster's reduce capacity, so that if a node fails the reduces can
  still be executed in a single wave.
  Ignored when mapred.job.tracker is "local".
  </description>
</property>

<property>
  <name>mapreduce.tasktracker.outofband.heartbeat</name>
  <value>false</value>
  <description>Expert: Set this to true to let the tasktracker send an
  out-of-band heartbeat on task-completion for better latency.
  </description>
</property>

<property>
  <name>mapreduce.tasktracker.outofband.heartbeat.damper</name>
  <value>1000000</value>
  <description>When out-of-band heartbeats are enabled, provides
  damping to avoid overwhelming the JobTracker if too many out-of-band
  heartbeats would occur. The damping is calculated such that the
  heartbeat interval is divided by (T*D + 1) where T is the number
  of completed tasks and D is the damper value.
 
  Setting this to a high value like the default provides no damping --
  as soon as any task finishes, a heartbeat will be sent. Setting this
  parameter to 0 is equivalent to disabling the out-of-band heartbeat feature.
  A value of 1 would indicate that, after one task has completed, the
  time to wait before the next heartbeat would be 1/2 the usual time.
  After two tasks have finished, it would be 1/3 the usual time, etc.
  </description>
</property>

<property>
  <name>mapred.jobtracker.restart.recover</name>
  <value>false</value>
  <description>"true" to enable (job) recovery upon restart,
               "false" to start afresh
  </description>
</property>

<property>
  <name>mapred.jobtracker.job.history.block.size</name>
  <value>3145728</value>
  <description>The block size of the job history file. Since the job recovery
               uses job history, its important to dump job history to disk as
               soon as possible. Note that this is an expert level parameter.
               The default value is set to 3 MB.
  </description>
</property>

<property>
  <name>mapreduce.job.split.metainfo.maxsize</name>
  <value>10000000</value>
  <description>The maximum permissible size of the split metainfo file.
  The JobTracker won't attempt to read split metainfo files bigger than
  the configured value.
  No limits if set to -1.
  </description>
</property>

<property>
  <name>mapred.jobtracker.taskScheduler</name>
  <value>org.apache.hadoop.mapred.JobQueueTaskScheduler</value>
  <description>The class responsible for scheduling the tasks.</description>
</property>

<property>
  <name>mapred.jobtracker.taskScheduler.maxRunningTasksPerJob</name>
  <value></value>
  <description>The maximum number of running tasks for a job before
  it gets preempted. No limits if undefined.
  </description>
</property>

<property>
  <name>mapred.map.max.attempts</name>
  <value>4</value>
  <description>Expert: The maximum number of attempts per map task.
  In other words, framework will try to execute a map task these many number
  of times before giving up on it.
  </description>
</property>

<property>
  <name>mapred.reduce.max.attempts</name>
  <value>4</value>
  <description>Expert: The maximum number of attempts per reduce task.
  In other words, framework will try to execute a reduce task these many number
  of times before giving up on it.
  </description>
</property>

<property>
  <name>mapred.reduce.parallel.copies</name>
  <value>5</value>
  <description>The default number of parallel transfers run by reduce
  during the copy(shuffle) phase.
  </description>
</property>

<property>
  <name>mapreduce.reduce.shuffle.maxfetchfailures</name>
  <value>10</value>
  <description>The maximum number of times a reducer tries to
  fetch a map output before it reports it.
</description></property>

<property>
  <name>mapreduce.reduce.shuffle.connect.timeout</name>
  <value>180000</value>
  <description>Expert: The maximum amount of time (in milli seconds) a reduce
  task spends in trying to connect to a tasktracker for getting map output.
  </description>
</property>

<property>
  <name>mapreduce.reduce.shuffle.read.timeout</name>
  <value>180000</value>
  <description>Expert: The maximum amount of time (in milli seconds) a reduce
  task waits for map output data to be available for reading after obtaining
  connection.
  </description>
</property>

<property>
  <name>mapred.task.timeout</name>
  <value>600000</value>
  <description>The number of milliseconds before a task will be
  terminated if it neither reads an input, writes an output, nor
  updates its status string.
  </description>
</property>

<property>
  <name>mapred.tasktracker.map.tasks.maximum</name>
  <value>2</value>
  <description>The maximum number of map tasks that will be run
  simultaneously by a task tracker.
  </description>
</property>

<property>
  <name>mapred.tasktracker.reduce.tasks.maximum</name>
  <value>2</value>
  <description>The maximum number of reduce tasks that will be run
  simultaneously by a task tracker.
  </description>
</property>

<property>
  <name>mapred.jobtracker.completeuserjobs.maximum</name>
  <value>100</value>
  <description>The maximum number of complete jobs per user to keep around
  before delegating them to the job history.</description>
</property>

<property>
  <name>mapreduce.reduce.input.limit</name>
  <value>-1</value>
  <description>The limit on the input size of the reduce. If the estimated
  input size of the reduce is greater than this value, job is failed. A
  value of -1 means that there is no limit set. </description>
</property>

<property>
  <name>mapred.job.tracker.retiredjobs.cache.size</name>
  <value>1000</value>
  <description>The number of retired job status to keep in the cache.
  </description>
</property>

<property>
  <name>mapred.job.tracker.jobhistory.lru.cache.size</name>
  <value>5</value>
  <description>The number of job history files loaded in memory. The jobs are
  loaded when they are first accessed. The cache is cleared based on LRU.
  </description>
</property>

<!--
<property>
  <name>mapred.jobtracker.instrumentation</name>
  <value>com.example.hadoop.JobTrackerInstrumentation</value>
  <description>Expert: The instrumentation class to associate with each JobTracker.
  </description>
</property>
-->

<property>
  <name>mapred.child.java.opts</name>
  <value>-Xmx200m</value>
  <description>Java opts for the task tracker child processes. 
  The following symbol, if present, will be interpolated: @taskid@ is replaced
  by current TaskID. Any other occurrences of '@' will go unchanged.
  For example, to enable verbose gc logging to a file named for the taskid in
  /tmp and to set the heap maximum to be a gigabyte, pass a 'value' of:
        -Xmx1024m -verbose:gc -Xloggc:/tmp/@taskid@.gc
 
  The configuration variable mapred.child.ulimit can be used to control the
  maximum virtual memory of the child processes.
  </description>
</property>

<property>
  <name>mapred.child.env</name>
  <value></value>
  <description>User added environment variables for the task tracker child
  processes. Example :
  1) A=foo  This will set the env variable A to foo
  2) B=$B:c This is inherit tasktracker's B env variable. 
  </description>
</property>

<property>
  <name>mapred.child.ulimit</name>
  <value></value>
  <description>The maximum virtual memory, in KB, of a process launched by the
  Map-Reduce framework. This can be used to control both the Mapper/Reducer
  tasks and applications using Hadoop Pipes, Hadoop Streaming etc.
  By default it is left unspecified to let cluster admins control it via
  limits.conf and other such relevant mechanisms.
 
  Note: mapred.child.ulimit must be greater than or equal to the -Xmx passed to
  JavaVM, else the VM might not start.
  </description>
</property>

<property>
  <name>mapred.cluster.map.memory.mb</name>
  <value>-1</value>
  <description>The size, in terms of virtual memory, of a single map slot
  in the Map-Reduce framework, used by the scheduler.
  A job can ask for multiple slots for a single map task via
  mapred.job.map.memory.mb, upto the limit specified by
  mapred.cluster.max.map.memory.mb, if the scheduler supports the feature.
  The value of -1 indicates that this feature is turned off.
  </description>
</property>

<property>
  <name>mapred.cluster.reduce.memory.mb</name>
  <value>-1</value>
  <description>The size, in terms of virtual memory, of a single reduce slot
  in the Map-Reduce framework, used by the scheduler.
  A job can ask for multiple slots for a single reduce task via
  mapred.job.reduce.memory.mb, upto the limit specified by
  mapred.cluster.max.reduce.memory.mb, if the scheduler supports the feature.
  The value of -1 indicates that this feature is turned off.
  </description>
</property>

<property>
  <name>mapred.cluster.max.map.memory.mb</name>
  <value>-1</value>
  <description>The maximum size, in terms of virtual memory, of a single map
  task launched by the Map-Reduce framework, used by the scheduler.
  A job can ask for multiple slots for a single map task via
  mapred.job.map.memory.mb, upto the limit specified by
  mapred.cluster.max.map.memory.mb, if the scheduler supports the feature.
  The value of -1 indicates that this feature is turned off.
  </description>
</property>

<property>
  <name>mapred.cluster.max.reduce.memory.mb</name>
  <value>-1</value>
  <description>The maximum size, in terms of virtual memory, of a single reduce
  task launched by the Map-Reduce framework, used by the scheduler.
  A job can ask for multiple slots for a single reduce task via
  mapred.job.reduce.memory.mb, upto the limit specified by
  mapred.cluster.max.reduce.memory.mb, if the scheduler supports the feature.
  The value of -1 indicates that this feature is turned off.
  </description>
</property>

<property>
  <name>mapred.job.map.memory.mb</name>
  <value>-1</value>
  <description>The size, in terms of virtual memory, of a single map task
  for the job.
  A job can ask for multiple slots for a single map task, rounded up to the
  next multiple of mapred.cluster.map.memory.mb and upto the limit
  specified by mapred.cluster.max.map.memory.mb, if the scheduler supports
  the feature.
  The value of -1 indicates that this feature is turned off iff
  mapred.cluster.map.memory.mb is also turned off (-1).
  </description>
</property>

<property>
  <name>mapred.job.reduce.memory.mb</name>
  <value>-1</value>
  <description>The size, in terms of virtual memory, of a single reduce task
  for the job.
  A job can ask for multiple slots for a single map task, rounded up to the
  next multiple of mapred.cluster.reduce.memory.mb and upto the limit
  specified by mapred.cluster.max.reduce.memory.mb, if the scheduler supports
  the feature.
  The value of -1 indicates that this feature is turned off iff
  mapred.cluster.reduce.memory.mb is also turned off (-1). 
  </description>
</property>

<property>
  <name>mapred.child.tmp</name>
  <value>./tmp</value>
  <description> To set the value of tmp directory for map and reduce tasks.
  If the value is an absolute path, it is directly assigned. Otherwise, it is
  prepended with task's working directory. The java tasks are executed with
  option -Djava.io.tmpdir='the absolute path of the tmp dir'. Pipes and
  streaming are set with environment variable,
   TMPDIR='the absolute path of the tmp dir'
  </description>
</property>

<property>
  <name>mapred.inmem.merge.threshold</name>
  <value>1000</value>
  <description>The threshold, in terms of the number of files
  for the in-memory merge process. When we accumulate threshold number of files
  we initiate the in-memory merge and spill to disk. A value of 0 or less than
  0 indicates we want to DON'T have any threshold and instead depend only on
  the ramfs's memory consumption to trigger the merge.
  </description>
</property>

<property>
  <name>mapred.job.shuffle.merge.percent</name>
  <value>0.66</value>
  <description>The usage threshold at which an in-memory merge will be
  initiated, expressed as a percentage of the total memory allocated to
  storing in-memory map outputs, as defined by
  mapred.job.shuffle.input.buffer.percent.
  </description>
</property>

<property>
  <name>mapred.job.shuffle.input.buffer.percent</name>
  <value>0.70</value>
  <description>The percentage of memory to be allocated from the maximum heap
  size to storing map outputs during the shuffle.
  </description>
</property>

<property>
  <name>mapred.job.reduce.input.buffer.percent</name>
  <value>0.0</value>
  <description>The percentage of memory- relative to the maximum heap size- to
  retain map outputs during the reduce. When the shuffle is concluded, any
  remaining map outputs in memory must consume less than this threshold before
  the reduce can begin.
  </description>
</property>

<property>
  <name>mapred.map.tasks.speculative.execution</name>
  <value>true</value>
  <description>If true, then multiple instances of some map tasks
               may be executed in parallel.</description>
</property>

<property>
  <name>mapred.reduce.tasks.speculative.execution</name>
  <value>true</value>
  <description>If true, then multiple instances of some reduce tasks
               may be executed in parallel.</description>
</property>

<property>
  <name>mapred.job.reuse.jvm.num.tasks</name>
  <value>1</value>
  <description>How many tasks to run per jvm. If set to -1, there is
  no limit.
  </description>
</property>

<property>
  <name>mapred.min.split.size</name>
  <value>0</value>
  <description>The minimum size chunk that map input should be split
  into.  Note that some file formats may have minimum split sizes that
  take priority over this setting.</description>
</property>

<property>
  <name>mapred.jobtracker.maxtasks.per.job</name>
  <value>-1</value>
  <description>The maximum number of tasks for a single job.
  A value of -1 indicates that there is no maximum.  </description>
</property>

<property>
  <name>mapred.submit.replication</name>
  <value>10</value>
  <description>The replication level for submitted job files.  This
  should be around the square root of the number of nodes.
  </description>
</property>


<property>
  <name>mapred.tasktracker.dns.interface</name>
  <value>default</value>
  <description>The name of the Network Interface from which a task
  tracker should report its IP address.
  </description>
</property>

<property>
  <name>mapred.tasktracker.dns.nameserver</name>
  <value>default</value>
  <description>The host name or IP address of the name server (DNS)
  which a TaskTracker should use to determine the host name used by
  the JobTracker for communication and display purposes.
  </description>
</property>

<property>
  <name>tasktracker.http.threads</name>
  <value>40</value>
  <description>The number of worker threads that for the http server. This is
               used for map output fetching
  </description>
</property>

<property>
  <name>mapred.task.tracker.http.address</name>
  <value>0.0.0.0:50060</value>
  <description>
    The task tracker http server address and port.
    If the port is 0 then the server will start on a free port.
  </description>
</property>

<property>
  <name>keep.failed.task.files</name>
  <value>false</value>
  <description>Should the files for failed tasks be kept. This should only be
               used on jobs that are failing, because the storage is never
               reclaimed. It also prevents the map outputs from being erased
               from the reduce directory as they are consumed.</description>
</property>


<!--
  <property>
  <name>keep.task.files.pattern</name>
  <value>.*_m_123456_0</value>
  <description>Keep all files from tasks whose task names match the given
               regular expression. Defaults to none.</description>
  </property>
-->

<property>
  <name>mapred.output.compress</name>
  <value>false</value>
  <description>Should the job outputs be compressed?
  </description>
</property>

<property>
  <name>mapred.output.compression.type</name>
  <value>RECORD</value>
  <description>If the job outputs are to compressed as SequenceFiles, how should
               they be compressed? Should be one of NONE, RECORD or BLOCK.
  </description>
</property>

<property>
  <name>mapred.output.compression.codec</name>
  <value>org.apache.hadoop.io.compress.DefaultCodec</value>
  <description>If the job outputs are compressed, how should they be compressed?
  </description>
</property>

<property>
  <name>mapred.compress.map.output</name>
  <value>false</value>
  <description>Should the outputs of the maps be compressed before being
               sent across the network. Uses SequenceFile compression.
  </description>
</property>

<property>
  <name>mapred.map.output.compression.codec</name>
  <value>org.apache.hadoop.io.compress.DefaultCodec</value>
  <description>If the map outputs are compressed, how should they be
               compressed?
  </description>
</property>

<property>
  <name>map.sort.class</name>
  <value>org.apache.hadoop.util.QuickSort</value>
  <description>The default sort class for sorting keys.
  </description>
</property>

<property>
  <name>mapred.userlog.limit.kb</name>
  <value>0</value>
  <description>The maximum size of user-logs of each task in KB. 0 disables the cap.
  </description>
</property>

<property>
  <name>mapred.userlog.retain.hours</name>
  <value>24</value>
  <description>The maximum time, in hours, for which the user-logs are to be
               retained after the job completion.
  </description>
</property>

<property>
  <name>mapred.user.jobconf.limit</name>
  <value>5242880</value>
  <description>The maximum allowed size of the user jobconf. The
  default is set to 5 MB</description>
</property>

<property>
  <name>mapred.hosts</name>
  <value></value>
  <description>Names a file that contains the list of nodes that may
  connect to the jobtracker.  If the value is empty, all hosts are
  permitted.</description>
</property>

<property>
  <name>mapred.hosts.exclude</name>
  <value></value>
  <description>Names a file that contains the list of hosts that
  should be excluded by the jobtracker.  If the value is empty, no
  hosts are excluded.</description>
</property>

<property>
  <name>mapred.heartbeats.in.second</name>
  <value>100</value>
  <description>Expert: Approximate number of heart-beats that could arrive
               at JobTracker in a second. Assuming each RPC can be processed
               in 10msec, the default value is made 100 RPCs in a second.
  </description>
</property>

<property>
  <name>mapred.max.tracker.blacklists</name>
  <value>4</value>
  <description>The number of blacklists for a tasktracker by various jobs
               after which the tasktracker will be marked as potentially
               faulty and is a candidate for graylisting across all jobs.
               (Unlike blacklisting, this is advisory; the tracker remains
               active.  However, it is reported as graylisted in the web UI,
               with the expectation that chronically graylisted trackers
               will be manually decommissioned.)  This value is tied to
               mapred.jobtracker.blacklist.fault-timeout-window; faults
               older than the window width are forgiven, so the tracker
               will recover from transient problems.  It will also become
               healthy after a restart.
  </description>
</property>

<property>
  <name>mapred.jobtracker.blacklist.fault-timeout-window</name>
  <value>180</value>
  <description>The timeout (in minutes) after which per-job tasktracker
               faults are forgiven.  The window is logically a circular
               buffer of time-interval buckets whose width is defined by
               mapred.jobtracker.blacklist.fault-bucket-width; when the
               "now" pointer moves across a bucket boundary, the previous
               contents (faults) of the new bucket are cleared.  In other
               words, the timeout's granularity is determined by the bucket
               width.
  </description>
</property>

<property>
  <name>mapred.jobtracker.blacklist.fault-bucket-width</name>
  <value>15</value>
  <description>The width (in minutes) of each bucket in the tasktracker
               fault timeout window.  Each bucket is reused in a circular
               manner after a full timeout-window interval (defined by
               mapred.jobtracker.blacklist.fault-timeout-window).
  </description>
</property>

<property>
  <name>mapred.max.tracker.failures</name>
  <value>4</value>
  <description>The number of task-failures on a tasktracker of a given job
               after which new tasks of that job aren't assigned to it.
  </description>
</property>

<property>
  <name>jobclient.output.filter</name>
  <value>FAILED</value>
  <description>The filter for controlling the output of the task's userlogs sent
               to the console of the JobClient.
               The permissible options are: NONE, KILLED, FAILED, SUCCEEDED and
               ALL.
  </description>
</property>

  <property>
    <name>mapred.job.tracker.persist.jobstatus.active</name>
    <value>false</value>
    <description>Indicates if persistency of job status information is
      active or not.
    </description>
  </property>

  <property>
  <name>mapred.job.tracker.persist.jobstatus.hours</name>
  <value>0</value>
  <description>The number of hours job status information is persisted in DFS.
    The job status information will be available after it drops of the memory
    queue and between jobtracker restarts. With a zero value the job status
    information is not persisted at all in DFS.
  </description>
</property>

  <property>
    <name>mapred.job.tracker.persist.jobstatus.dir</name>
    <value>/jobtracker/jobsInfo</value>
    <description>The directory where the job status information is persisted
      in a file system to be available after it drops of the memory queue and
      between jobtracker restarts.
    </description>
  </property>

  <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>

  <property>
    <name>mapred.task.profile</name>
    <value>false</value>
    <description>To set whether the system should collect profiler
     information for some of the tasks in this job? The information is stored
     in the user log directory. The value is "true" if task profiling
     is enabled.</description>
  </property>

  <property>
    <name>mapred.task.profile.maps</name>
    <value>0-2</value>
    <description> To set the ranges of map tasks to profile.
    mapred.task.profile has to be set to true for the value to be accounted.
    </description>
  </property>

  <property>
    <name>mapred.task.profile.reduces</name>
    <value>0-2</value>
    <description> To set the ranges of reduce tasks to profile.
    mapred.task.profile has to be set to true for the value to be accounted.
    </description>
  </property>

  <property>
    <name>mapred.line.input.format.linespermap</name>
    <value>1</value>
    <description> Number of lines per split in NLineInputFormat.
    </description>
  </property>
 
  <property>
    <name>mapred.skip.attempts.to.start.skipping</name>
    <value>2</value>
    <description> The number of Task attempts AFTER which skip mode
    will be kicked off. When skip mode is kicked off, the
    tasks reports the range of records which it will process
    next, to the TaskTracker. So that on failures, TT knows which
    ones are possibly the bad records. On further executions,
    those are skipped.
    </description>
  </property>
 
  <property>
    <name>mapred.skip.map.auto.incr.proc.count</name>
    <value>true</value>
    <description> The flag which if set to true,
    SkipBadRecords.COUNTER_MAP_PROCESSED_RECORDS is incremented
    by MapRunner after invoking the map function. This value must be set to
    false for applications which process the records asynchronously
    or buffer the input records. For example streaming.
    In such cases applications should increment this counter on their own.
    </description>
  </property>
 
  <property>
    <name>mapred.skip.reduce.auto.incr.proc.count</name>
    <value>true</value>
    <description> The flag which if set to true,
    SkipBadRecords.COUNTER_REDUCE_PROCESSED_GROUPS is incremented
    by framework after invoking the reduce function. This value must be set to
    false for applications which process the records asynchronously
    or buffer the input records. For example streaming.
    In such cases applications should increment this counter on their own.
    </description>
  </property>
 
  <property>
    <name>mapred.skip.out.dir</name>
    <value></value>
    <description> If no value is specified here, the skipped records are
    written to the output directory at _logs/skip.
    User can stop writing skipped records by giving the value "none".
    </description>
  </property>

  <property>
    <name>mapred.skip.map.max.skip.records</name>
    <value>0</value>
    <description> The number of acceptable skip records surrounding the bad
    record PER bad record in mapper. The number includes the bad record as well.
    To turn the feature of detection/skipping of bad records off, set the
    value to 0.
    The framework tries to narrow down the skipped range by retrying 
    until this threshold is met OR all attempts get exhausted for this task.
    Set the value to Long.MAX_VALUE to indicate that framework need not try to
    narrow down. Whatever records(depends on application) get skipped are
    acceptable.
    </description>
  </property>
 
  <property>
    <name>mapred.skip.reduce.max.skip.groups</name>
    <value>0</value>
    <description> The number of acceptable skip groups surrounding the bad
    group PER bad group in reducer. The number includes the bad group as well.
    To turn the feature of detection/skipping of bad groups off, set the
    value to 0.
    The framework tries to narrow down the skipped range by retrying 
    until this threshold is met OR all attempts get exhausted for this task.
    Set the value to Long.MAX_VALUE to indicate that framework need not try to
    narrow down. Whatever groups(depends on application) get skipped are
    acceptable.
    </description>
  </property>
 
<!-- Job Notification Configuration -->

<!--
<property>
<name>job.end.notification.url</name>
<value>http://localhost:8080/jobstatus.php?jobId=$jobId&amp;jobStatus=$jobStatus</value>
<description>Indicates url which will be called on completion of job to inform
              end status of job.
              User can give at most 2 variables with URI : $jobId and $jobStatus.
              If they are present in URI, then they will be replaced by their
              respective values.
</description>
</property>
-->

<property>
  <name>job.end.retry.attempts</name>
  <value>0</value>
  <description>Indicates how many times hadoop should attempt to contact the
               notification URL </description>
</property>

<property>
  <name>job.end.retry.interval</name>
   <value>30000</value>
   <description>Indicates time in milliseconds between notification URL retry
                calls</description>
</property>
 
<!-- Proxy Configuration -->
<property>
  <name>hadoop.rpc.socket.factory.class.JobSubmissionProtocol</name>
  <value></value>
  <description> SocketFactory to use to connect to a Map/Reduce master
    (JobTracker). If null or empty, then use hadoop.rpc.socket.class.default.
  </description>
</property>

<property>
  <name>mapred.task.cache.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>

<property>
  <name>mapred.queue.names</name>
  <value>default</value>
  <description> Comma separated list of queues configured for this jobtracker.
    Jobs are added to queues and schedulers can configure different
    scheduling properties for the various queues. To configure a property
    for a queue, the name of the queue must match the name specified in this
    value. Queue properties that are common to all schedulers are configured
    here with the naming convention, mapred.queue.$QUEUE-NAME.$PROPERTY-NAME,
    for e.g. mapred.queue.default.submit-job-acl.
    The number of queues configured in this parameter could depend on the
    type of scheduler being used, as specified in
    mapred.jobtracker.taskScheduler. For example, the JobQueueTaskScheduler
    supports only a single queue, which is the default configured here.
    Before adding more queues, ensure that the scheduler you've configured
    supports multiple queues.
  </description>
</property>

<property>
  <name>mapred.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.
  </description>
</property>

<property>
  <name>mapred.queue.default.state</name>
  <value>RUNNING</value>
  <description>
   This values defines the state , default queue is in.
   the values can be either "STOPPED" or "RUNNING"
   This value can be changed at runtime.
  </description>
</property>

<property>
  <name>mapred.job.queue.name</name>
  <value>default</value>
  <description> Queue to which a job is submitted. This must match one of the
    queues defined in mapred.queue.names 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>

<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 mapred.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, job-owner, the user who started the
    cluster, cluster administrators configured via
    mapreduce.cluster.administrators and queue administrators of the queue to
    which this job is submitted to configured via
    mapred.queue.queue-name.acl-administer-jobs  in mapred-queue-acls.xml can
    do all the modification operations on a job.

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

<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 mapred.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, job-owner, the user who started the
    cluster, cluster administrators configured via
    mapreduce.cluster.administrators and queue administrators of the queue to
    which this job is submitted to configured via
    mapred.queue.queue-name.acl-administer-jobs in mapred-queue-acls.xml can do
    all the view operations on a job.
   
    By default, nobody else besides job-owner, the user who started the
    cluster, cluster administrators and queue administrators can perform
    view operations on a job.
  </description>
</property>

<property>
  <name>mapred.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>

<property>
  <name>mapred.combine.recordsBeforeProgress</name>
  <value>10000</value>
  <description> The number of records to process during combine output collection
   before sending a progress notification to the TaskTracker.
  </description>
</property>

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

<property>
  <name>mapred.reduce.slowstart.completed.maps</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>

<property>
  <name>mapred.task.tracker.task-controller</name>
  <value>org.apache.hadoop.mapred.DefaultTaskController</value>
  <description>TaskController which is used to launch and manage task execution
  </description>
</property>

<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>

<!--  Node health script variables -->

<property>
  <name>mapred.healthChecker.script.path</name>
  <value></value>
  <description>Absolute path to the script which is
  periodicallyrun by the node health monitoring service to determine if
  the node is healthy or not. If the value of this key is empty or the
  file does not exist in the location configured here, the node health
  monitoring service is not started.</description>
</property>

<property>
  <name>mapred.healthChecker.interval</name>
  <value>60000</value>
  <description>Frequency of the node health script to be run,
  in milliseconds</description>
</property>

<property>
  <name>mapred.healthChecker.script.timeout</name>
  <value>600000</value>
  <description>Time after node health script should be killed if
  unresponsive and considered that the script has failed.</description>
</property>

<property>
  <name>mapred.healthChecker.script.args</name>
  <value></value>
  <description>List of arguments which are to be passed to
  node health script when it is being launched comma seperated.
  </description>
</property>

<property>
  <name>mapreduce.job.counters.limit</name>
  <value>120</value>
  <description>Limit on the number of counters allowed per job.
  </description>
</property>

<!--  end of node health script variables -->

</configuration>