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From ni...@apache.org
Subject svn commit: r726985 [2/2] - in /hadoop/core/trunk/docs: cn/core-default.html cn/hdfs-default.html cn/mapred-default.html core-default.html hdfs-default.html mapred-default.html
Date Tue, 16 Dec 2008 08:38:40 GMT
Added: hadoop/core/trunk/docs/mapred-default.html
URL: http://svn.apache.org/viewvc/hadoop/core/trunk/docs/mapred-default.html?rev=726985&view=auto
==============================================================================
--- hadoop/core/trunk/docs/mapred-default.html (added)
+++ hadoop/core/trunk/docs/mapred-default.html Tue Dec 16 00:38:39 2008
@@ -0,0 +1,667 @@
+<html>
+<body>
+<table border="1">
+<tr>
+<td>name</td><td>value</td><td>description</td>
+</tr>
+<tr>
+<td><a name="hadoop.job.history.location">hadoop.job.history.location</a></td><td></td><td>
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.
+  </td>
+</tr>
+<tr>
+<td><a name="hadoop.job.history.user.location">hadoop.job.history.user.location</a></td><td></td><td>
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". 
+  </td>
+</tr>
+<tr>
+<td><a name="io.sort.factor">io.sort.factor</a></td><td>10</td><td>The
number of streams to merge at once while sorting
+  files.  This determines the number of open file handles.</td>
+</tr>
+<tr>
+<td><a name="io.sort.mb">io.sort.mb</a></td><td>100</td><td>The
total amount of buffer memory to use while sorting 
+  files, in megabytes.  By default, gives each merge stream 1MB, which
+  should minimize seeks.</td>
+</tr>
+<tr>
+<td><a name="io.sort.record.percent">io.sort.record.percent</a></td><td>0.05</td><td>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</td>
+</tr>
+<tr>
+<td><a name="io.sort.spill.percent">io.sort.spill.percent</a></td><td>0.80</td><td>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.</td>
+</tr>
+<tr>
+<td><a name="io.map.index.skip">io.map.index.skip</a></td><td>0</td><td>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.</td>
+</tr>
+<tr>
+<td><a name="mapred.job.tracker">mapred.job.tracker</a></td><td>local</td><td>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.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.job.tracker.http.address">mapred.job.tracker.http.address</a></td><td>0.0.0.0:50030</td><td>
+    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.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.job.tracker.handler.count">mapred.job.tracker.handler.count</a></td><td>10</td><td>
+    The number of server threads for the JobTracker. This should be roughly
+    4% of the number of tasktracker nodes.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.task.tracker.report.address">mapred.task.tracker.report.address</a></td><td>127.0.0.1:0</td><td>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.</td>
+</tr>
+<tr>
+<td><a name="mapred.local.dir">mapred.local.dir</a></td><td>${hadoop.tmp.dir}/mapred/local</td><td>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.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.system.dir">mapred.system.dir</a></td><td>${hadoop.tmp.dir}/mapred/system</td><td>The
shared directory where MapReduce stores control files.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.temp.dir">mapred.temp.dir</a></td><td>${hadoop.tmp.dir}/mapred/temp</td><td>A
shared directory for temporary files.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.local.dir.minspacestart">mapred.local.dir.minspacestart</a></td><td>0</td><td>If
the space in mapred.local.dir drops under this, 
+  do not ask for more tasks.
+  Value in bytes.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.local.dir.minspacekill">mapred.local.dir.minspacekill</a></td><td>0</td><td>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.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.tasktracker.expiry.interval">mapred.tasktracker.expiry.interval</a></td><td>600000</td><td>Expert:
The time-interval, in miliseconds, after which
+  a tasktracker is declared 'lost' if it doesn't send heartbeats.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.tasktracker.instrumentation">mapred.tasktracker.instrumentation</a></td><td>org.apache.hadoop.mapred.TaskTrackerMetricsInst</td><td>Expert:
The instrumentation class to associate with each TaskTracker.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.tasktracker.vmem.reserved">mapred.tasktracker.vmem.reserved</a></td><td>-1</td><td>Configuration
property to specify the amount of virtual memory
+    that has to be reserved by the TaskTracker for system usage (OS, TT etc).
+    The reserved virtual memory should be a part of the total virtual memory
+    available on the TaskTracker.
+    
+    The reserved virtual memory and the total virtual memory values are
+    reported by the TaskTracker as part of heart-beat so that they can
+    considered by a scheduler. Please refer to the documentation of the
+    configured scheduler to see how this property is used.
+    
+    These two values are also used by a TaskTracker for tracking tasks' memory
+    usage. Memory management functionality on a TaskTracker is disabled if this
+    property is set to -1, if it more than the total virtual memory on the 
+    tasktracker, or if either of the values is negative.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.tasktracker.pmem.reserved">mapred.tasktracker.pmem.reserved</a></td><td>-1</td><td>Configuration
property to specify the amount of physical memory
+    that has to be reserved by the TaskTracker for system usage (OS, TT etc).
+    The reserved physical memory should be a part of the total physical memory
+    available on the TaskTracker.
+
+    The reserved physical memory and the total physical memory values are
+    reported by the TaskTracker as part of heart-beat so that they can
+    considered by a scheduler. Please refer to the documentation of the
+    configured scheduler to see how this property is used.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.task.default.maxvmem">mapred.task.default.maxvmem</a></td><td>-1</td><td>
+    Cluster-wide configuration in bytes to be set by the administrators that
+    provides default amount of maximum virtual memory for job's tasks. This has
+    to be set on both the JobTracker node for the sake of scheduling decisions
+    and on the TaskTracker nodes for the sake of memory management.
+
+    If a job doesn't specify its virtual memory requirement by setting
+    mapred.task.maxvmem to -1, tasks are assured a memory limit set
+    to this property. This property is set to -1 by default.
+
+    This value should in general be less than the cluster-wide
+    configuration mapred.task.limit.maxvmem. If not or if it is not set,
+    TaskTracker's memory management will be disabled and a scheduler's memory
+    based scheduling decisions may be affected. Please refer to the
+    documentation of the configured scheduler to see how this property is used.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.task.limit.maxvmem">mapred.task.limit.maxvmem</a></td><td>-1</td><td>
+    Cluster-wide configuration in bytes to be set by the site administrators
+    that provides an upper limit on the maximum virtual memory that can be
+    specified by a job via mapred.task.maxvmem. This has to be set on both the
+    JobTracker node for the sake of scheduling decisions and on the TaskTracker
+    nodes for the sake of memory management.
+    
+    The job configuration mapred.task.maxvmem should not be more than this
+    value, otherwise depending on the scheduler being configured, the job may
+    be rejected or the job configuration may just be ignored. Please refer to
+    the documentation of the configured scheduler to see how this property is
+    used.
+
+    If it is not set a TaskTracker, TaskTracker's memory management will be
+    disabled.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.task.maxvmem">mapred.task.maxvmem</a></td><td>-1</td><td>
+    The maximum amount of virtual memory any task of a job will use, in bytes.
+
+    This value will be used by TaskTrackers for monitoring the memory usage of
+    tasks of this jobs. If a TaskTracker's memory management functionality is
+    enabled, each task of this job will be allowed to use a maximum virtual
+    memory specified by this property. If the task's memory usage goes over 
+    this value, the task will be failed by the TT. If not set, the
+    cluster-wide configuration mapred.task.default.maxvmem is used as the
+    default value for memory requirements. If this property cascaded with
+    mapred.task.default.maxvmem becomes equal to -1, the job's tasks will
+    not be assured any particular amount of virtual memory and may be killed by
+    a TT that intends to control the total memory usage of the tasks via memory
+    management functionality. If the memory management functionality is
+    disabled on a TT, this value is ignored.
+
+    This value should not be more than the cluster-wide configuration
+    mapred.task.limit.maxvmem.
+
+    This value may be used by schedulers that support scheduling based on job's
+    memory requirements. Please refer to the documentation of the scheduler
+    being configured to see if it does memory based scheduling and if it does,
+    how this property is used by that scheduler.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.task.maxpmem">mapred.task.maxpmem</a></td><td>-1</td><td>
+   The maximum amount of physical memory any task of a job will use in bytes.
+
+   This value may be used by schedulers that support scheduling based on job's
+   memory requirements. In general, a task of this job will be scheduled on a
+   TaskTracker, only if the amount of physical memory still unoccupied on the
+   TaskTracker is greater than or equal to this value. Different schedulers can
+   take different decisions, some might just ignore this value. Please refer to
+   the documentation of the scheduler being configured to see if it does
+   memory based scheduling and if it does, how this variable is used by that
+   scheduler.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.tasktracker.memory_calculator_plugin">mapred.tasktracker.memory_calculator_plugin</a></td><td></td><td>
+   Name of the class whose instance will be used to query memory information
+   on the tasktracker.
+   
+   The class must be an instance of 
+   org.apache.hadoop.util.MemoryCalculatorPlugin. If the value is null, the
+   tasktracker attempts to use a class appropriate to the platform. 
+   Currently, the only platform supported is Linux.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.tasktracker.taskmemorymanager.monitoring-interval">mapred.tasktracker.taskmemorymanager.monitoring-interval</a></td><td>5000</td><td>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.
+   </td>
+</tr>
+<tr>
+<td><a name="mapred.tasktracker.procfsbasedprocesstree.sleeptime-before-sigkill">mapred.tasktracker.procfsbasedprocesstree.sleeptime-before-sigkill</a></td><td>5000</td><td>The
time, in milliseconds, the tasktracker waits for sending a
+  SIGKILL to a process that has overrun memory limits, after it has been sent
+  a SIGTERM. Used only if tasks' memory management is enabled via
+  mapred.tasktracker.tasks.maxmemory.</td>
+</tr>
+<tr>
+<td><a name="mapred.map.tasks">mapred.map.tasks</a></td><td>2</td><td>The
default number of map tasks per job.  Typically set
+  to a prime several times greater than number of available hosts.
+  Ignored when mapred.job.tracker is "local".  
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.reduce.tasks">mapred.reduce.tasks</a></td><td>1</td><td>The
default number of reduce tasks per job.  Typically set
+  to a prime close to the number of available hosts.  Ignored when
+  mapred.job.tracker is "local".
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.jobtracker.restart.recover">mapred.jobtracker.restart.recover</a></td><td>false</td><td>"true"
to enable (job) recovery upon restart,
+               "false" to start afresh
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.jobtracker.job.history.block.size">mapred.jobtracker.job.history.block.size</a></td><td>3145728</td><td>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.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.jobtracker.taskScheduler">mapred.jobtracker.taskScheduler</a></td><td>org.apache.hadoop.mapred.JobQueueTaskScheduler</td><td>The
class responsible for scheduling the tasks.</td>
+</tr>
+<tr>
+<td><a name="mapred.jobtracker.taskScheduler.maxRunningTasksPerJob">mapred.jobtracker.taskScheduler.maxRunningTasksPerJob</a></td><td></td><td>The
maximum number of running tasks for a job before
+  it gets preempted. No limits if undefined.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.map.max.attempts">mapred.map.max.attempts</a></td><td>4</td><td>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.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.reduce.max.attempts">mapred.reduce.max.attempts</a></td><td>4</td><td>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.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.reduce.parallel.copies">mapred.reduce.parallel.copies</a></td><td>5</td><td>The
default number of parallel transfers run by reduce
+  during the copy(shuffle) phase.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.reduce.copy.backoff">mapred.reduce.copy.backoff</a></td><td>300</td><td>The
maximum amount of time (in seconds) a reducer spends on 
+  fetching one map output before declaring it as failed.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.task.timeout">mapred.task.timeout</a></td><td>600000</td><td>The
number of milliseconds before a task will be
+  terminated if it neither reads an input, writes an output, nor
+  updates its status string.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.tasktracker.map.tasks.maximum">mapred.tasktracker.map.tasks.maximum</a></td><td>2</td><td>The
maximum number of map tasks that will be run
+  simultaneously by a task tracker.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.tasktracker.reduce.tasks.maximum">mapred.tasktracker.reduce.tasks.maximum</a></td><td>2</td><td>The
maximum number of reduce tasks that will be run
+  simultaneously by a task tracker.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.jobtracker.completeuserjobs.maximum">mapred.jobtracker.completeuserjobs.maximum</a></td><td>100</td><td>The
maximum number of complete jobs per user to keep around 
+  before delegating them to the job history.</td>
+</tr>
+<tr>
+<td><a name="mapred.jobtracker.instrumentation">mapred.jobtracker.instrumentation</a></td><td>org.apache.hadoop.mapred.JobTrackerMetricsInst</td><td>Expert:
The instrumentation class to associate with each JobTracker.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.child.java.opts">mapred.child.java.opts</a></td><td>-Xmx200m</td><td>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. 
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.child.ulimit">mapred.child.ulimit</a></td><td></td><td>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. 
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.child.tmp">mapred.child.tmp</a></td><td>./tmp</td><td>
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'
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.inmem.merge.threshold">mapred.inmem.merge.threshold</a></td><td>1000</td><td>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.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.job.shuffle.merge.percent">mapred.job.shuffle.merge.percent</a></td><td>0.66</td><td>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.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.job.shuffle.input.buffer.percent">mapred.job.shuffle.input.buffer.percent</a></td><td>0.70</td><td>The
percentage of memory to be allocated from the maximum heap
+  size to storing map outputs during the shuffle.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.job.reduce.input.buffer.percent">mapred.job.reduce.input.buffer.percent</a></td><td>0.0</td><td>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.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.map.tasks.speculative.execution">mapred.map.tasks.speculative.execution</a></td><td>true</td><td>If
true, then multiple instances of some map tasks 
+               may be executed in parallel.</td>
+</tr>
+<tr>
+<td><a name="mapred.reduce.tasks.speculative.execution">mapred.reduce.tasks.speculative.execution</a></td><td>true</td><td>If
true, then multiple instances of some reduce tasks 
+               may be executed in parallel.</td>
+</tr>
+<tr>
+<td><a name="mapred.job.reuse.jvm.num.tasks">mapred.job.reuse.jvm.num.tasks</a></td><td>1</td><td>How
many tasks to run per jvm. If set to -1, there is
+  no limit. 
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.min.split.size">mapred.min.split.size</a></td><td>0</td><td>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.</td>
+</tr>
+<tr>
+<td><a name="mapred.jobtracker.maxtasks.per.job">mapred.jobtracker.maxtasks.per.job</a></td><td>-1</td><td>The
maximum number of tasks for a single job.
+  A value of -1 indicates that there is no maximum.  </td>
+</tr>
+<tr>
+<td><a name="mapred.submit.replication">mapred.submit.replication</a></td><td>10</td><td>The
replication level for submitted job files.  This
+  should be around the square root of the number of nodes.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.tasktracker.dns.interface">mapred.tasktracker.dns.interface</a></td><td>default</td><td>The
name of the Network Interface from which a task
+  tracker should report its IP address.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.tasktracker.dns.nameserver">mapred.tasktracker.dns.nameserver</a></td><td>default</td><td>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.
+  </td>
+</tr>
+<tr>
+<td><a name="tasktracker.http.threads">tasktracker.http.threads</a></td><td>40</td><td>The
number of worker threads that for the http server. This is
+               used for map output fetching
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.task.tracker.http.address">mapred.task.tracker.http.address</a></td><td>0.0.0.0:50060</td><td>
+    The task tracker http server address and port.
+    If the port is 0 then the server will start on a free port.
+  </td>
+</tr>
+<tr>
+<td><a name="keep.failed.task.files">keep.failed.task.files</a></td><td>false</td><td>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.</td>
+</tr>
+<tr>
+<td><a name="mapred.output.compress">mapred.output.compress</a></td><td>false</td><td>Should
the job outputs be compressed?
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.output.compression.type">mapred.output.compression.type</a></td><td>RECORD</td><td>If
the job outputs are to compressed as SequenceFiles, how should
+               they be compressed? Should be one of NONE, RECORD or BLOCK.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.output.compression.codec">mapred.output.compression.codec</a></td><td>org.apache.hadoop.io.compress.DefaultCodec</td><td>If
the job outputs are compressed, how should they be compressed?
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.compress.map.output">mapred.compress.map.output</a></td><td>false</td><td>Should
the outputs of the maps be compressed before being
+               sent across the network. Uses SequenceFile compression.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.map.output.compression.codec">mapred.map.output.compression.codec</a></td><td>org.apache.hadoop.io.compress.DefaultCodec</td><td>If
the map outputs are compressed, how should they be 
+               compressed?
+  </td>
+</tr>
+<tr>
+<td><a name="map.sort.class">map.sort.class</a></td><td>org.apache.hadoop.util.QuickSort</td><td>The
default sort class for sorting keys.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.userlog.limit.kb">mapred.userlog.limit.kb</a></td><td>0</td><td>The
maximum size of user-logs of each task in KB. 0 disables the cap.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.userlog.retain.hours">mapred.userlog.retain.hours</a></td><td>24</td><td>The
maximum time, in hours, for which the user-logs are to be 
+          retained.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.hosts">mapred.hosts</a></td><td></td><td>Names
a file that contains the list of nodes that may
+  connect to the jobtracker.  If the value is empty, all hosts are
+  permitted.</td>
+</tr>
+<tr>
+<td><a name="mapred.hosts.exclude">mapred.hosts.exclude</a></td><td></td><td>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.</td>
+</tr>
+<tr>
+<td><a name="mapred.max.tracker.blacklists">mapred.max.tracker.blacklists</a></td><td>4</td><td>The
number of blacklists for a taskTracker by various jobs
+               after which the task tracker could be blacklisted across
+               all jobs. The tracker will be given a tasks later
+               (after a day). The tracker will become a healthy
+               tracker after a restart.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.max.tracker.failures">mapred.max.tracker.failures</a></td><td>4</td><td>The
number of task-failures on a tasktracker of a given job 
+               after which new tasks of that job aren't assigned to it.
+  </td>
+</tr>
+<tr>
+<td><a name="jobclient.output.filter">jobclient.output.filter</a></td><td>FAILED</td><td>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.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.job.tracker.persist.jobstatus.active">mapred.job.tracker.persist.jobstatus.active</a></td><td>false</td><td>Indicates
if persistency of job status information is
+      active or not.
+    </td>
+</tr>
+<tr>
+<td><a name="mapred.job.tracker.persist.jobstatus.hours">mapred.job.tracker.persist.jobstatus.hours</a></td><td>0</td><td>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.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.job.tracker.persist.jobstatus.dir">mapred.job.tracker.persist.jobstatus.dir</a></td><td>/jobtracker/jobsInfo</td><td>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.
+    </td>
+</tr>
+<tr>
+<td><a name="mapred.task.profile">mapred.task.profile</a></td><td>false</td><td>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.</td>
+</tr>
+<tr>
+<td><a name="mapred.task.profile.maps">mapred.task.profile.maps</a></td><td>0-2</td><td>
To set the ranges of map tasks to profile.
+    mapred.task.profile has to be set to true for the value to be accounted.
+    </td>
+</tr>
+<tr>
+<td><a name="mapred.task.profile.reduces">mapred.task.profile.reduces</a></td><td>0-2</td><td>
To set the ranges of reduce tasks to profile.
+    mapred.task.profile has to be set to true for the value to be accounted.
+    </td>
+</tr>
+<tr>
+<td><a name="mapred.line.input.format.linespermap">mapred.line.input.format.linespermap</a></td><td>1</td><td>
Number of lines per split in NLineInputFormat.
+    </td>
+</tr>
+<tr>
+<td><a name="mapred.skip.attempts.to.start.skipping">mapred.skip.attempts.to.start.skipping</a></td><td>2</td><td>
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.
+    </td>
+</tr>
+<tr>
+<td><a name="mapred.skip.map.auto.incr.proc.count">mapred.skip.map.auto.incr.proc.count</a></td><td>true</td><td>
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.
+    </td>
+</tr>
+<tr>
+<td><a name="mapred.skip.reduce.auto.incr.proc.count">mapred.skip.reduce.auto.incr.proc.count</a></td><td>true</td><td>
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.
+    </td>
+</tr>
+<tr>
+<td><a name="mapred.skip.out.dir">mapred.skip.out.dir</a></td><td></td><td>
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". 
+    </td>
+</tr>
+<tr>
+<td><a name="mapred.skip.map.max.skip.records">mapred.skip.map.max.skip.records</a></td><td>0</td><td>
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.
+    </td>
+</tr>
+<tr>
+<td><a name="mapred.skip.reduce.max.skip.groups">mapred.skip.reduce.max.skip.groups</a></td><td>0</td><td>
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.
+    </td>
+</tr>
+<tr>
+<td><a name="job.end.retry.attempts">job.end.retry.attempts</a></td><td>0</td><td>Indicates
how many times hadoop should attempt to contact the
+               notification URL </td>
+</tr>
+<tr>
+<td><a name="job.end.retry.interval">job.end.retry.interval</a></td><td>30000</td><td>Indicates
time in milliseconds between notification URL retry
+                calls</td>
+</tr>
+<tr>
+<td><a name="hadoop.rpc.socket.factory.class.JobSubmissionProtocol">hadoop.rpc.socket.factory.class.JobSubmissionProtocol</a></td><td></td><td>
SocketFactory to use to connect to a Map/Reduce master
+    (JobTracker). If null or empty, then use hadoop.rpc.socket.class.default.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.task.cache.levels">mapred.task.cache.levels</a></td><td>2</td><td>
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.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.queue.names">mapred.queue.names</a></td><td>default</td><td>
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.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.acls.enabled">mapred.acls.enabled</a></td><td>false</td><td>
Specifies whether ACLs are enabled, and should be checked
+    for various operations.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.queue.default.acl-submit-job">mapred.queue.default.acl-submit-job</a></td><td>*</td><td>
Comma separated list of user and group names that are allowed
+    to submit jobs to the 'default' queue. The user list and the group list
+    are separated by a blank. For e.g. alice,bob group1,group2. 
+    If set to the special value '*', it means all users are allowed to 
+    submit jobs. 
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.queue.default.acl-administer-jobs">mapred.queue.default.acl-administer-jobs</a></td><td>*</td><td>
Comma separated list of user and group names that are allowed
+    to delete jobs or modify job's priority for jobs not owned by the current
+    user in the 'default' queue. The user list and the group list
+    are separated by a blank. For e.g. alice,bob group1,group2. 
+    If set to the special value '*', it means all users are allowed to do 
+    this operation.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.job.queue.name">mapred.job.queue.name</a></td><td>default</td><td>
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.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.tasktracker.indexcache.mb">mapred.tasktracker.indexcache.mb</a></td><td>10</td><td>
The maximum memory that a task tracker allows for the 
+    index cache that is used when serving map outputs to reducers.
+  </td>
+</tr>
+<tr>
+<td><a name="mapred.merge.recordsBeforeProgress">mapred.merge.recordsBeforeProgress</a></td><td>10000</td><td>
The number of records to process during merge before
+   sending a progress notification to the TaskTracker.
+  </td>
+</tr>
+</table>
+</body>
+</html>



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