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+<html>
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+<body>
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+<table border="1">
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+<tr>
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+<td>name</td><td>value</td><td>description</td>
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+</tr>
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+<tr>
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+<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
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+ in this single well known place. If No value is set here, by default,
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+ it is in the local file system at ${hadoop.log.dir}/history.
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+ </td>
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+</tr>
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+<tr>
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+<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
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+ a particular job. If nothing is specified, the logs are stored in
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+ output directory. The files are stored in "_logs/history/" in the directory.
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+ User can stop logging by giving the value "none".
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+ </td>
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+</tr>
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+<tr>
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+<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
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+ files. This determines the number of open file handles.</td>
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+</tr>
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+<tr>
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+<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
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+ files, in megabytes. By default, gives each merge stream 1MB, which
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+ should minimize seeks.</td>
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+</tr>
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+<tr>
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+<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
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+ boundaries. Let this value be r, io.sort.mb be x. The maximum number
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+ of records collected before the collection thread must block is equal
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+ to (r * x) / 4</td>
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+</tr>
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+<tr>
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+<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
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+ buffers. Once reached, a thread will begin to spill the contents to disk
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+ in the background. Note that this does not imply any chunking of data to
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+ the spill. A value less than 0.5 is not recommended.</td>
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+</tr>
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+<tr>
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+<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.
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+ Zero by default. Setting this to values larger than zero can
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+ facilitate opening large map files using less memory.</td>
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+</tr>
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+<tr>
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+<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
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+ at. If "local", then jobs are run in-process as a single map
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+ and reduce task.
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+ </td>
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+</tr>
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+<tr>
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+<td><a name="mapred.job.tracker.http.address">mapred.job.tracker.http.address</a></td><td>0.0.0.0:50030</td><td>
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+ The job tracker http server address and port the server will listen on.
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+ If the port is 0 then the server will start on a free port.
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+ </td>
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+</tr>
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+<tr>
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+<td><a name="mapred.job.tracker.handler.count">mapred.job.tracker.handler.count</a></td><td>10</td><td>
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+ The number of server threads for the JobTracker. This should be roughly
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+ 4% of the number of tasktracker nodes.
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+ </td>
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+</tr>
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+<tr>
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+<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.
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+ Since it is only connected to by the tasks, it uses the local interface.
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+ EXPERT ONLY. Should only be changed if your host does not have the loopback
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+ interface.</td>
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+</tr>
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+<tr>
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+<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
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+ data files. May be a comma-separated list of
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+ directories on different devices in order to spread disk i/o.
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+ Directories that do not exist are ignored.
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+ </td>
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+</tr>
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+<tr>
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+<td><a name="mapred.system.dir">mapred.system.dir</a></td><td>${hadoop.tmp.dir}/mapred/system</td><td>The shared directory where MapReduce stores control files.
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+ </td>
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+</tr>
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+<tr>
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+<td><a name="mapred.temp.dir">mapred.temp.dir</a></td><td>${hadoop.tmp.dir}/mapred/temp</td><td>A shared directory for temporary files.
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+ </td>
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+</tr>
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+<tr>
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+<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,
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+ do not ask for more tasks.
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+ Value in bytes.
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+ </td>
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+</tr>
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+<tr>
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+<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,
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+ do not ask more tasks until all the current ones have finished and
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+ cleaned up. Also, to save the rest of the tasks we have running,
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+ kill one of them, to clean up some space. Start with the reduce tasks,
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+ then go with the ones that have finished the least.
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+ Value in bytes.
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+ </td>
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+</tr>
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+<tr>
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+<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
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+ a tasktracker is declared 'lost' if it doesn't send heartbeats.
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+ </td>
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+</tr>
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+<tr>
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+<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.
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+ </td>
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+</tr>
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+<tr>
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+<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
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+ that has to be reserved by the TaskTracker for system usage (OS, TT etc).
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+ The reserved virtual memory should be a part of the total virtual memory
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+ available on the TaskTracker.
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+
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+ The reserved virtual memory and the total virtual memory values are
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+ reported by the TaskTracker as part of heart-beat so that they can
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+ considered by a scheduler. Please refer to the documentation of the
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+ configured scheduler to see how this property is used.
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+
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+ These two values are also used by a TaskTracker for tracking tasks' memory
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+ usage. Memory management functionality on a TaskTracker is disabled if this
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+ property is set to -1, if it more than the total virtual memory on the
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+ tasktracker, or if either of the values is negative.
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+ </td>
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+</tr>
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+<tr>
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+<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
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+ that has to be reserved by the TaskTracker for system usage (OS, TT etc).
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+ The reserved physical memory should be a part of the total physical memory
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+ available on the TaskTracker.
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+
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+ The reserved physical memory and the total physical memory values are
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+ reported by the TaskTracker as part of heart-beat so that they can
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+ considered by a scheduler. Please refer to the documentation of the
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+ configured scheduler to see how this property is used.
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+ </td>
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+</tr>
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+<tr>
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+<td><a name="mapred.task.default.maxvmem">mapred.task.default.maxvmem</a></td><td>-1</td><td>
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+ Cluster-wide configuration in bytes to be set by the administrators that
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+ provides default amount of maximum virtual memory for job's tasks. This has
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+ to be set on both the JobTracker node for the sake of scheduling decisions
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+ and on the TaskTracker nodes for the sake of memory management.
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+
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+ If a job doesn't specify its virtual memory requirement by setting
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+ mapred.task.maxvmem to -1, tasks are assured a memory limit set
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+ to this property. This property is set to -1 by default.
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+
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+ This value should in general be less than the cluster-wide
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+ configuration mapred.task.limit.maxvmem. If not or if it is not set,
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+ TaskTracker's memory management will be disabled and a scheduler's memory
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+ based scheduling decisions may be affected. Please refer to the
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+ documentation of the configured scheduler to see how this property is used.
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+ </td>
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+</tr>
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+<tr>
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+<td><a name="mapred.task.limit.maxvmem">mapred.task.limit.maxvmem</a></td><td>-1</td><td>
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+ Cluster-wide configuration in bytes to be set by the site administrators
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+ that provides an upper limit on the maximum virtual memory that can be
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+ specified by a job via mapred.task.maxvmem. This has to be set on both the
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+ JobTracker node for the sake of scheduling decisions and on the TaskTracker
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+ nodes for the sake of memory management.
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+
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+ The job configuration mapred.task.maxvmem should not be more than this
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+ value, otherwise depending on the scheduler being configured, the job may
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+ be rejected or the job configuration may just be ignored. Please refer to
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+ the documentation of the configured scheduler to see how this property is
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+ used.
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+
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+ If it is not set a TaskTracker, TaskTracker's memory management will be
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+ disabled.
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+ </td>
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+</tr>
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+<tr>
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+<td><a name="mapred.task.maxvmem">mapred.task.maxvmem</a></td><td>-1</td><td>
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+ The maximum amount of virtual memory any task of a job will use, in bytes.
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+
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+ This value will be used by TaskTrackers for monitoring the memory usage of
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+ tasks of this jobs. If a TaskTracker's memory management functionality is
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+ enabled, each task of this job will be allowed to use a maximum virtual
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+ memory specified by this property. If the task's memory usage goes over
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+ this value, the task will be failed by the TT. If not set, the
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+ cluster-wide configuration mapred.task.default.maxvmem is used as the
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+ default value for memory requirements. If this property cascaded with
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+ mapred.task.default.maxvmem becomes equal to -1, the job's tasks will
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+ not be assured any particular amount of virtual memory and may be killed by
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+ a TT that intends to control the total memory usage of the tasks via memory
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+ management functionality. If the memory management functionality is
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+ disabled on a TT, this value is ignored.
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+
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+ This value should not be more than the cluster-wide configuration
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+ mapred.task.limit.maxvmem.
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+
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+ This value may be used by schedulers that support scheduling based on job's
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+ memory requirements. Please refer to the documentation of the scheduler
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+ being configured to see if it does memory based scheduling and if it does,
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+ how this property is used by that scheduler.
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+ </td>
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+</tr>
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+<tr>
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+<td><a name="mapred.task.maxpmem">mapred.task.maxpmem</a></td><td>-1</td><td>
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+ The maximum amount of physical memory any task of a job will use in bytes.
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+
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+ This value may be used by schedulers that support scheduling based on job's
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+ memory requirements. In general, a task of this job will be scheduled on a
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+ TaskTracker, only if the amount of physical memory still unoccupied on the
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+ TaskTracker is greater than or equal to this value. Different schedulers can
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+ take different decisions, some might just ignore this value. Please refer to
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+ the documentation of the scheduler being configured to see if it does
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+ memory based scheduling and if it does, how this variable is used by that
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+ scheduler.
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+ </td>
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+</tr>
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+<tr>
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+<td><a name="mapred.tasktracker.memory_calculator_plugin">mapred.tasktracker.memory_calculator_plugin</a></td><td></td><td>
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+ Name of the class whose instance will be used to query memory information
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+ on the tasktracker.
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+
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+ The class must be an instance of
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+ org.apache.hadoop.util.MemoryCalculatorPlugin. If the value is null, the
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+ tasktracker attempts to use a class appropriate to the platform.
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+ Currently, the only platform supported is Linux.
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+ </td>
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+</tr>
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+<tr>
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+<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
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+ between two cycles of monitoring its tasks' memory usage. Used only if
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+ tasks' memory management is enabled via mapred.tasktracker.tasks.maxmemory.
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+ </td>
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+</tr>
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+<tr>
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+<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
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+ SIGKILL to a process that has overrun memory limits, after it has been sent
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+ a SIGTERM. Used only if tasks' memory management is enabled via
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+ mapred.tasktracker.tasks.maxmemory.</td>
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+</tr>
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+<tr>
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+<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
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+ to a prime several times greater than number of available hosts.
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+ Ignored when mapred.job.tracker is "local".
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+ </td>
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+</tr>
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+<tr>
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+<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
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+ to a prime close to the number of available hosts. Ignored when
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+ mapred.job.tracker is "local".
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+ </td>
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+</tr>
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+<tr>
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+<td><a name="mapred.jobtracker.restart.recover">mapred.jobtracker.restart.recover</a></td><td>false</td><td>"true" to enable (job) recovery upon restart,
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+ "false" to start afresh
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+ </td>
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+</tr>
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+<tr>
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+<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
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+ uses job history, its important to dump job history to disk as
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+ soon as possible. Note that this is an expert level parameter.
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+ The default value is set to 3 MB.
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+ </td>
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+</tr>
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+<tr>
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+<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>
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+</tr>
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+<tr>
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+<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
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+ it gets preempted. No limits if undefined.
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+ </td>
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+</tr>
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+<tr>
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+<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.
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+ In other words, framework will try to execute a map task these many number
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+ of times before giving up on it.
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+ </td>
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+</tr>
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+<tr>
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+<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.
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+ In other words, framework will try to execute a reduce task these many number
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+ of times before giving up on it.
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+ </td>
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+</tr>
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+<tr>
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+<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
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+ during the copy(shuffle) phase.
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+ </td>
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+</tr>
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+<tr>
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+<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
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+ fetching one map output before declaring it as failed.
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+ </td>
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+</tr>
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+<tr>
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+<td><a name="mapred.task.timeout">mapred.task.timeout</a></td><td>600000</td><td>The number of milliseconds before a task will be
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+ terminated if it neither reads an input, writes an output, nor
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+ updates its status string.
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+ </td>
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+</tr>
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+<tr>
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+<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
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+ simultaneously by a task tracker.
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+ </td>
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+</tr>
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+<tr>
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+<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
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+ simultaneously by a task tracker.
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+ </td>
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+</tr>
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+<tr>
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+<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
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+ before delegating them to the job history.</td>
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+</tr>
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+<tr>
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+<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.
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+ </td>
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+</tr>
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+<tr>
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+<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.
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+ The following symbol, if present, will be interpolated: @taskid@ is replaced
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+ 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>
|
|
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+<tr>
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+<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
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+ to submit jobs to the 'default' queue. The user list and the group list
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+ are separated by a blank. For e.g. alice,bob group1,group2.
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+ If set to the special value '*', it means all users are allowed to
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+ submit jobs.
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+ </td>
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+</tr>
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+<tr>
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+<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
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+ to delete jobs or modify job's priority for jobs not owned by the current
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+ user in the 'default' queue. The user list and the group list
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+ are separated by a blank. For e.g. alice,bob group1,group2.
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+ If set to the special value '*', it means all users are allowed to do
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+ this operation.
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+ </td>
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+</tr>
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+<tr>
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+<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
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+ queues defined in mapred.queue.names for the system. Also, the ACL setup
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+ for the queue must allow the current user to submit a job to the queue.
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+ Before specifying a queue, ensure that the system is configured with
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+ the queue, and access is allowed for submitting jobs to the queue.
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+ </td>
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+</tr>
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+<tr>
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+<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
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+ index cache that is used when serving map outputs to reducers.
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+ </td>
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+</tr>
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+<tr>
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+<td><a name="mapred.merge.recordsBeforeProgress">mapred.merge.recordsBeforeProgress</a></td><td>10000</td><td> The number of records to process during merge before
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+ sending a progress notification to the TaskTracker.
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+ </td>
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+</tr>
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+</table>
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+</body>
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+</html>
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Nigel Daley