Module: Wukong::HadoopCommand

Included in:
Script
Defined in:
lib/wukong/script/hadoop_command.rb

Defined Under Namespace

Modules: ClassMethods

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.included(base) ⇒ Object

Standard ClassMethods-on-include trick



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# File 'lib/wukong/script/hadoop_command.rb', line 182

def self.included base
  base.class_eval do
    extend ClassMethods
  end
end

Instance Method Details

#execute_hadoop_workflow ⇒ Object

Assemble the hadoop command to execute and launch the hadoop runner to execute the script across all tasktrackers

FIXME: Should add some simple logic to ensure that commands are in the right order or hadoop will complain. ie. -D options MUST come before others



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# File 'lib/wukong/script/hadoop_command.rb', line 59

def execute_hadoop_workflow
  # Input paths join by ','
  input_paths = @input_paths.join(',')
  #
  # Use Settings[:hadoop_home] to set the path your config install.
  hadoop_commandline = [
    hadoop_runner,
    "jar #{options[:hadoop_home]}/contrib/streaming/hadoop-*streaming*.jar",
    hadoop_jobconf_options,
    "-D mapred.job.name='#{job_name}'",
    hadoop_other_args,
    "-mapper  '#{mapper_commandline(:hadoop)}'",
    "-reducer '#{reducer_commandline(:hadoop)}'",
    "-input   '#{input_paths}'",
    "-output  '#{output_path}'",
    "-file    '#{this_script_filename}'",
    hadoop_recycle_env,
  ].flatten.compact.join(" \t\\\n  ")
  Log.info "  Launching hadoop!"
  execute_command!(hadoop_commandline)
end

#hadoop_jobconf_options ⇒ Object 



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# File 'lib/wukong/script/hadoop_command.rb', line 81

def hadoop_jobconf_options
  jobconf_options = []
  # Fixup these options
  options[:reuse_jvms] = '-1'             if (options[:reuse_jvms] == true)
  options[:respect_exit_status] = 'false' if (options[:ignore_exit_status] == true)
  # If no reducer and no reduce_command, then skip the reduce phase
  options[:reduce_tasks] = 0 if (! reducer) && (! options[:reduce_command]) && (! options[:reduce_tasks])
  # Fields hadoop should use to distribute records to reducers
  unless options[:partition_fields].blank?
    jobconf_options += [
      jobconf(:partition_fields),
      jobconf(:output_field_separator),
    ]
  end
  jobconf_options += [
    :io_sort_mb,               :io_sort_record_percent,
    :map_speculative,          :map_tasks,
    :max_maps_per_cluster,     :max_maps_per_node,
    :max_node_map_tasks,       :max_node_reduce_tasks,
    :max_reduces_per_cluster,  :max_reduces_per_node,
    :max_record_length,        :min_split_size,
    :output_field_separator,   :key_field_separator,
    :partition_fields,         :sort_fields,
    :reduce_tasks,             :respect_exit_status,
    :reuse_jvms,               :timeout,
    :max_tracker_failures,     :max_map_attempts,
    :max_reduce_attempts
  ].map{|opt| jobconf(opt)}
  jobconf_options.flatten.compact
end

#hadoop_other_args ⇒ Object 



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# File 'lib/wukong/script/hadoop_command.rb', line 112

def hadoop_other_args
  extra_str_args  = [ options[:extra_args] ]
  if options.split_on_xml_tag
    extra_str_args << %Q{-inputreader 'StreamXmlRecordReader,begin=<#{options.split_on_xml_tag}>,end=</#{options.split_on_xml_tag}>'}
  end
  extra_str_args   << ' -lazyOutput' if options[:noempty]  # don't create reduce file if no records
  extra_str_args   << ' -partitioner org.apache.hadoop.mapred.lib.KeyFieldBasedPartitioner' unless options[:partition_fields].blank?
  extra_str_args
end

#hadoop_recycle_env ⇒ Object 



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# File 'lib/wukong/script/hadoop_command.rb', line 122

def hadoop_recycle_env
  %w[RUBYLIB].map do |var|
    %Q{-cmdenv '#{var}=#{ENV[var]}'} if ENV[var]
  end.compact
end

#hadoop_runner ⇒ Object

The path to the hadoop runner script



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# File 'lib/wukong/script/hadoop_command.rb', line 129

def hadoop_runner
  options[:hadoop_runner] || (options[:hadoop_home]+'/bin/hadoop')
end

#jobconf(option) ⇒ Object

emit a -jobconf hadoop option if the simplified command line arg is present if not, the resulting nil will be elided later



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# File 'lib/wukong/script/hadoop_command.rb', line 44

def jobconf option
  if options[option]
    # "-jobconf %s=%s" % [options.definition_of(option, :description), options[option]]
    "-D %s=%s" % [options.definition_of(option, :description), options[option]]
  end
end