chef/cookbooks/hadoop/templates/default/mapred-site.xml.erb
<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>
<!--
Cookbook: hadoop
Filename: mapred-site.xml
Copyright (c) 2011 Dell Inc.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
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<!-- Generated by Chef for <%= @node[:fqdn] %> -->
<configuration>
<property>
<name>hadoop.job.history.location</name>
<value><%= node[:hadoop][:mapred][:hadoop_job_history_location] %></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><%= node[:hadoop][:mapred][:hadoop_job_history_user_location] %></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>hadoop.rpc.socket.factory.class.JobSubmissionProtocol</name>
<value><%= node[:hadoop][:mapred][:hadoop_rpc_socket_factory_class_JobSubmissionProtocol] %></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>io.map.index.skip</name>
<value><%= node[:hadoop][:mapred][:io_map_index_skip] %></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>io.sort.factor</name>
<value><%= node[:hadoop][:mapred][:io_sort_factor] %></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><%= node[:hadoop][:mapred][:io_sort_mb] %></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><%= node[:hadoop][:mapred][:io_sort_record_percent] %></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><%= node[:hadoop][:mapred][:io_sort_spill_percent] %></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>job.end.retry.attempts</name>
<value><%= node[:hadoop][:mapred][:job_end_retry_attempts] %></value>
<description>Indicates how many times hadoop should attempt to contact the
notification URL.
</description>
</property>
<property>
<name>job.end.retry.interval</name>
<value><%= node[:hadoop][:mapred][:job_end_retry_interval] %></value>
<description>Indicates time in milliseconds between notification URL retry calls.
</description>
</property>
<property>
<name>jobclient.output.filter</name>
<value><%= node[:hadoop][:mapred][:jobclient_output_filter] %></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>keep.failed.task.files</name>
<value><%= node[:hadoop][:mapred][:keep_failed_task_files] %></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>map.sort.class</name>
<value><%= node[:hadoop][:mapred][:map_sort_class] %></value>
<description>The default sort class for sorting keys.
</description>
</property>
<property>
<name>mapred.acls.enabled</name>
<value><%= node[:hadoop][:mapred][:mapred_acls_enabled] %></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.child.env</name>
<value><%= node[:hadoop][:mapred][:mapred_child_env] %></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.java.opts</name>
<value><%= node[:hadoop][:mapred][:mapred_child_java_opts] %></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.tmp</name>
<value><%= node[:hadoop][:mapred][:mapred_child_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.child.ulimit</name>
<value><%= node[:hadoop][:mapred][:mapred_child_ulimit] %></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><%= node[:hadoop][:mapred][:mapred_cluster_map_memory_mb] %></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.max.map.memory.mb</name>
<value><%= node[:hadoop][:mapred][:mapred_cluster_max_map_memory_mb] %></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><%= node[:hadoop][:mapred][:mapred_cluster_max_reduce_memory_mb] %></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.cluster.reduce.memory.mb</name>
<value><%= node[:hadoop][:mapred][:mapred_cluster_reduce_memory_mb] %></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.compress.map.output</name>
<value><%= node[:hadoop][:mapred][:mapred_compress_map_output] %></value>
<description>Should the outputs of the maps be compressed before being sent across
the network. Uses SequenceFile compression.
</description>
</property>
<property>
<name>mapred.healthChecker.interval</name>
<value><%= node[:hadoop][:mapred][:mapred_healthChecker_interval] %></value>
<description>Frequency of the node health script to be run, in milliseconds.
</description>
</property>
<property>
<name>mapred.healthChecker.script.args</name>
<value><%= node[:hadoop][:mapred][:mapred_healthChecker_script_args] %></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>mapred.healthChecker.script.path</name>
<value><%= node[:hadoop][:mapred][:mapred_healthChecker_script_path] %></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.script.timeout</name>
<value><%= node[:hadoop][:mapred][:mapred_healthChecker_script_timeout] %></value>
<description>Time after node health script should be killed if unresponsive and
considered that the script has failed.
</description>
</property>
<property>
<name>mapred.heartbeats.in.second</name>
<value><%= node[:hadoop][:mapred][:mapred_heartbeats_in_second] %></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.hosts</name>
<value><%= node[:hadoop][:mapred][:mapred_hosts] %></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><%= node[:hadoop][:mapred][:mapred_hosts_exclude] %></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.inmem.merge.threshold</name>
<value><%= node[:hadoop][:mapred][:mapred_inmem_merge_threshold] %></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.map.memory.mb</name>
<value><%= node[:hadoop][:mapred][:mapred_job_map_memory_mb] %></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.queue.name</name>
<value><%= node[:hadoop][:mapred][:mapred_job_queue_name] %></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>mapred.job.reduce.input.buffer.percent</name>
<value><%= node[:hadoop][:mapred][:mapred_job_reduce_input_buffer_percent] %></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.job.reduce.memory.mb</name>
<value><%= node[:hadoop][:mapred][:mapred_job_reduce_memory_mb] %></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.job.reuse.jvm.num.tasks</name>
<value><%= node[:hadoop][:mapred][:mapred_job_reuse_jvm_num_tasks] %></value>
<description>How many tasks to run per jvm. If set to -1, there is no limit.
</description>
</property>
<property>
<name>mapred.job.shuffle.input.buffer.percent</name>
<value><%= node[:hadoop][:mapred][:mapred_job_shuffle_input_buffer_percent] %></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.shuffle.merge.percent</name>
<value><%= node[:hadoop][:mapred][:mapred_job_shuffle_merge_percent] %></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.tracker</name>
<value><%= node[:hadoop][:mapred][:mapred_job_tracker] %></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.handler.count</name>
<value><%= node[:hadoop][:mapred][:mapred_job_tracker_handler_count] %></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.job.tracker.history.completed.location</name>
<value><%= node[:hadoop][:mapred][:mapred_job_tracker_history_completed_location] %></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>
<property>
<name>mapred.job.tracker.http.address</name>
<value><%= node[:hadoop][:mapred][:mapred_job_tracker_http_address] %></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.jobhistory.lru.cache.size</name>
<value><%= node[:hadoop][:mapred][:mapred_job_tracker_jobhistory_lru_cache_size] %></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.job.tracker.persist.jobstatus.active</name>
<value><%= node[:hadoop][:mapred][:mapred_job_tracker_persist_jobstatus_active] %></value>
<description>Indicates if persistency of job status information is active or not.
</description>
</property>
<property>
<name>mapred.job.tracker.persist.jobstatus.dir</name>
<value><%= node[:hadoop][:mapred][:mapred_job_tracker_persist_jobstatus_dir] %></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>mapred.job.tracker.persist.jobstatus.hours</name>
<value><%= node[:hadoop][:mapred][:mapred_job_tracker_persist_jobstatus_hours] %></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.retiredjobs.cache.size</name>
<value><%= node[:hadoop][:mapred][:mapred_job_tracker_retiredjobs_cache_size] %></value>
<description>The number of retired job status to keep in the cache.
</description>
</property>
<property>
<name>mapred.jobtracker.blacklist.fault-bucket-width</name>
<value><%= node[:hadoop][:mapred][:mapred_jobtracker_blacklist_fault_bucket_width] %></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.jobtracker.blacklist.fault-timeout-window</name>
<value><%= node[:hadoop][:mapred][:mapred_jobtracker_blacklist_fault_timeout_window] %></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.completeuserjobs.maximum</name>
<value><%= node[:hadoop][:mapred][:mapred_jobtracker_completeuserjobs_maximum] %></value>
<description>The maximum number of complete jobs per user to keep around before
delegating them to the job history.
</description>
</property>
<property>
<name>mapred.jobtracker.job.history.block.size</name>
<value><%= node[:hadoop][:mapred][:mapred_jobtracker_job_history_block_size] %></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>mapred.jobtracker.maxtasks.per.job</name>
<value><%= node[:hadoop][:mapred][:mapred_jobtracker_maxtasks_per_job] %></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.jobtracker.restart.recover</name>
<value><%= node[:hadoop][:mapred][:mapred_jobtracker_restart_recover] %></value>
<description>"true" to enable (job) recovery upon restart, "false" to start
afresh.
</description>
</property>
<property>
<name>mapred.jobtracker.taskScheduler</name>
<value><%= node[:hadoop][:mapred][:mapred_jobtracker_taskScheduler] %></value>
<description>The class responsible for scheduling the tasks.
</description>
</property>
<property>
<name>mapred.jobtracker.taskScheduler.maxRunningTasksPerJob</name>
<value><%= node[:hadoop][:mapred][:mapred_jobtracker_taskScheduler_maxRunningTasksPerJob] %></value>
<description>The maximum number of running tasks for a job before it gets
preempted. No limits if undefined.
</description>
</property>
<property>
<name>mapred.line.input.format.linespermap</name>
<value><%= node[:hadoop][:mapred][:mapred_line_input_format_linespermap] %></value>
<description>Number of lines per split in NLineInputFormat.
</description>
</property>
<property>
<name>mapred.local.dir</name>
<value><%= node[:hadoop][:mapred][:mapred_local_dir].join(",") %></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.local.dir.minspacekill</name>
<value><%= node[:hadoop][:mapred][:mapred_local_dir_minspacekill] %></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.local.dir.minspacestart</name>
<value><%= node[:hadoop][:mapred][:mapred_local_dir_minspacestart] %></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.map.max.attempts</name>
<value><%= node[:hadoop][:mapred][:mapred_map_max_attempts] %></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.map.output.compression.codec</name>
<value><%= node[:hadoop][:mapred][:mapred_map_output_compression_codec] %></value>
<description>If the map outputs are compressed, how should they be compressed?.
</description>
</property>
<property>
<name>mapred.map.tasks</name>
<value><%= node[:hadoop][:mapred][:mapred_map_tasks] %></value>
<description>The default number of map tasks per job. Ignored when
mapred.job.tracker is "local".
</description>
</property>
<property>
<name>mapred.map.tasks.speculative.execution</name>
<value><%= node[:hadoop][:mapred][:mapred_map_tasks_speculative_execution] %></value>
<description>If true, then multiple instances of some map tasks may be executed in
parallel.
</description>
</property>
<property>
<name>mapred.max.tracker.blacklists</name>
<value><%= node[:hadoop][:mapred][:mapred_max_tracker_blacklists] %></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.max.tracker.failures</name>
<value><%= node[:hadoop][:mapred][:mapred_max_tracker_failures] %></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>mapred.merge.recordsBeforeProgress</name>
<value><%= node[:hadoop][:mapred][:mapred_merge_recordsBeforeProgress] %></value>
<description>The number of records to process during merge before sending a
progress notification to the TaskTracker.
</description>
</property>
<property>
<name>mapred.min.split.size</name>
<value><%= node[:hadoop][:mapred][:mapred_min_split_size] %></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.output.compress</name>
<value><%= node[:hadoop][:mapred][:mapred_output_compress] %></value>
<description>Should the job outputs be compressed?.
</description>
</property>
<property>
<name>mapred.output.compression.codec</name>
<value><%= node[:hadoop][:mapred][:mapred_output_compression_codec] %></value>
<description>If the job outputs are compressed, how should they be compressed?.
</description>
</property>
<property>
<name>mapred.output.compression.type</name>
<value><%= node[:hadoop][:mapred][:mapred_output_compression_type] %></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.queue.default.state</name>
<value><%= node[:hadoop][:mapred][:mapred_queue_default_state] %></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.queue.names</name>
<value><%= node[:hadoop][:mapred][:mapred_queue_names] %></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.reduce.copy.backoff</name>
<value><%= node[:hadoop][:mapred][:mapred_reduce_copy_backoff] %></value>
<description>The maximum amount of time (in seconds) a reducer spends on fetching
one map output before declaring it as failed.
</description>
</property>
<property>
<name>mapred.reduce.max.attempts</name>
<value><%= node[:hadoop][:mapred][:mapred_reduce_max_attempts] %></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><%= node[:hadoop][:mapred][:mapred_reduce_parallel_copies] %></value>
<description>The default number of parallel transfers run by reduce during the
copy(shuffle) phase.
</description>
</property>
<property>
<name>mapred.reduce.slowstart.completed.maps</name>
<value><%= node[:hadoop][:mapred][:mapred_reduce_slowstart_completed_maps] %></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.reduce.tasks</name>
<value><%= node[:hadoop][:mapred][:mapred_reduce_tasks] %></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>mapred.reduce.tasks.speculative.execution</name>
<value><%= node[:hadoop][:mapred][:mapred_reduce_tasks_speculative_execution] %></value>
<description>If true, then multiple instances of some reduce tasks may be executed
in parallel.
</description>
</property>
<property>
<name>mapred.skip.attempts.to.start.skipping</name>
<value><%= node[:hadoop][:mapred][:mapred_skip_attempts_to_start_skipping] %></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><%= node[:hadoop][:mapred][:mapred_skip_map_auto_incr_proc_count] %></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.map.max.skip.records</name>
<value><%= node[:hadoop][:mapred][:mapred_skip_map_max_skip_records] %></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.out.dir</name>
<value><%= node[:hadoop][:mapred][:mapred_skip_out_dir] %></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.reduce.auto.incr.proc.count</name>
<value><%= node[:hadoop][:mapred][:mapred_skip_reduce_auto_incr_proc_count] %></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.reduce.max.skip.groups</name>
<value><%= node[:hadoop][:mapred][:mapred_skip_reduce_max_skip_groups] %></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>
<property>
<name>mapred.submit.replication</name>
<value><%= node[:hadoop][:mapred][:mapred_submit_replication] %></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.system.dir</name>
<value><%= node[:hadoop][:mapred][:mapred_system_dir] %></value>
<description>The directory where MapReduce stores control files.
</description>
</property>
<property>
<name>mapred.task.cache.levels</name>
<value><%= node[:hadoop][:mapred][:mapred_task_cache_levels] %></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.task.profile</name>
<value><%= node[:hadoop][:mapred][:mapred_task_profile] %></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><%= node[:hadoop][:mapred][:mapred_task_profile_maps] %></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><%= node[:hadoop][:mapred][:mapred_task_profile_reduces] %></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.task.timeout</name>
<value><%= node[:hadoop][:mapred][:mapred_task_timeout] %></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.task.tracker.http.address</name>
<value><%= node[:hadoop][:mapred][:mapred_task_tracker_http_address] %></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>mapred.task.tracker.report.address</name>
<value><%= node[:hadoop][:mapred][:mapred_task_tracker_report_address] %></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.task.tracker.task-controller</name>
<value><%= node[:hadoop][:mapred][:mapred_task_tracker_task_controller] %></value>
<description>TaskController which is used to launch and manage task execution.
</description>
</property>
<property>
<name>mapred.tasktracker.dns.interface</name>
<value><%= node[:hadoop][:mapred][:mapred_tasktracker_dns_interface] %></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><%= node[:hadoop][:mapred][:mapred_tasktracker_dns_nameserver] %></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>mapred.tasktracker.expiry.interval</name>
<value><%= node[:hadoop][:mapred][:mapred_tasktracker_expiry_interval] %></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.indexcache.mb</name>
<value><%= node[:hadoop][:mapred][:mapred_tasktracker_indexcache_mb] %></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.tasktracker.map.tasks.maximum</name>
<value><%= node[:hadoop][:mapred][:mapred_tasktracker_map_tasks_maximum] %></value>
<description>The maximum number of map tasks that will be run simultaneously by a
task tracker.
</description>
</property>
<property>
<name>mapred.tasktracker.memory_calculator_plugin</name>
<value><%= node[:hadoop][:mapred][:mapred_tasktracker_memory_calculator_plugin] %></value>
<description>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.
</description>
</property>
<property>
<name>mapred.tasktracker.reduce.tasks.maximum</name>
<value><%= node[:hadoop][:mapred][:mapred_tasktracker_reduce_tasks_maximum] %></value>
<description>The maximum number of reduce tasks that will be run simultaneously by
a task tracker.
</description>
</property>
<property>
<name>mapred.tasktracker.taskmemorymanager.monitoring-interval</name>
<value><%= node[:hadoop][:mapred][:mapred_tasktracker_taskmemorymanager_monitoring_interval] %></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><%= node[:hadoop][:mapred][:mapred_tasktracker_tasks_sleeptime_before_sigkill] %></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.temp.dir</name>
<value><%= node[:hadoop][:mapred][:mapred_temp_dir] %></value>
<description>A shared directory for temporary files.
</description>
</property>
<property>
<name>mapred.user.jobconf.limit</name>
<value><%= node[:hadoop][:mapred][:mapred_user_jobconf_limit] %></value>
<description>The maximum allowed size of the user jobconf. The default is set to 5
MB.
</description>
</property>
<property>
<name>mapred.userlog.limit.kb</name>
<value><%= node[:hadoop][:mapred][:mapred_userlog_limit_kb] %></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><%= node[:hadoop][:mapred][:mapred_userlog_retain_hours] %></value>
<description>The maximum time, in hours, for which the user-logs are to be
retained after the job completion.
</description>
</property>
<property>
<name>mapreduce.job.acl-modify-job</name>
<value><%= node[:hadoop][:mapred][:mapreduce_job_acl_modify_job] %></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><%= node[:hadoop][:mapred][:mapreduce_job_acl_view_job] %></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>mapreduce.job.complete.cancel.delegation.tokens</name>
<value><%= node[:hadoop][:mapred][:mapreduce_job_complete_cancel_delegation_tokens] %></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>mapreduce.job.counters.limit</name>
<value><%= node[:hadoop][:mapred][:mapreduce_job_counters_limit] %></value>
<description>Limit on the number of counters allowed per job.
</description>
</property>
<property>
<name>mapreduce.job.split.metainfo.maxsize</name>
<value><%= node[:hadoop][:mapred][:mapreduce_job_split_metainfo_maxsize] %></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>mapreduce.jobtracker.staging.root.dir</name>
<value><%= node[:hadoop][:mapred][:mapreduce_jobtracker_staging_root_dir] %></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>mapreduce.reduce.input.limit</name>
<value><%= node[:hadoop][:mapred][:mapreduce_reduce_input_limit] %></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>mapreduce.reduce.shuffle.connect.timeout</name>
<value><%= node[:hadoop][:mapred][:mapreduce_reduce_shuffle_connect_timeout] %></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><%= node[:hadoop][:mapred][:mapreduce_reduce_shuffle_read_timeout] %></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>mapreduce.tasktracker.group</name>
<value><%= node[:hadoop][:mapred][:mapreduce_tasktracker_group] %></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>
<property>
<name>mapreduce.tasktracker.outofband.heartbeat</name>
<value><%= node[:hadoop][:mapred][:mapreduce_tasktracker_outofband_heartbeat] %></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>tasktracker.http.threads</name>
<value><%= node[:hadoop][:mapred][:tasktracker_http_threads] %></value>
<description>The number of worker threads that for the http server. This is used
for map output fetching.
</description>
</property>
</configuration>