org.apache.pig.backend.hadoop.executionengine.mapReduceLayer
Class MapReduceLauncher

java.lang.Object
  extended by org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.Launcher
      extended by org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MapReduceLauncher

public class MapReduceLauncher
extends Launcher

Main class that launches pig for Map Reduce


Field Summary
static String SUCCEEDED_FILE_NAME
           
static String SUCCESSFUL_JOB_OUTPUT_DIR_MARKER
           
 
Constructor Summary
MapReduceLauncher()
           
 
Method Summary
 void explain(PhysicalPlan php, PigContext pc, PrintStream ps, String format, boolean verbose)
          Explain how a pig job will be executed on the underlying infrastructure.
 Exception getError(FileSpec spec)
          Get the exception that caused a failure on the backend for a store location (if any).
 PigStats launchPig(PhysicalPlan php, String grpName, PigContext pc)
          Method to launch pig for hadoop either for a cluster's job tracker or for a local job runner.
 void reset()
          Resets the state after a launch
 
Methods inherited from class org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.Launcher
calculateProgress, computeTimeSpent, getErrorMessages, getFirstLineFromMessage, getStackTraceElement, getStats, getTotalHadoopTimeSpent, isComplete, progressOfRunningJob
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

SUCCEEDED_FILE_NAME

public static final String SUCCEEDED_FILE_NAME
See Also:
Constant Field Values

SUCCESSFUL_JOB_OUTPUT_DIR_MARKER

public static final String SUCCESSFUL_JOB_OUTPUT_DIR_MARKER
See Also:
Constant Field Values
Constructor Detail

MapReduceLauncher

public MapReduceLauncher()
Method Detail

getError

public Exception getError(FileSpec spec)
Get the exception that caused a failure on the backend for a store location (if any).


reset

public void reset()
Description copied from class: Launcher
Resets the state after a launch

Overrides:
reset in class Launcher

launchPig

public PigStats launchPig(PhysicalPlan php,
                          String grpName,
                          PigContext pc)
                   throws PlanException,
                          VisitorException,
                          IOException,
                          ExecException,
                          JobCreationException,
                          Exception
Description copied from class: Launcher
Method to launch pig for hadoop either for a cluster's job tracker or for a local job runner. THe only difference between the two is the job client. Depending on the pig context the job client will be initialize to one of the two. Launchers for other frameworks can overide these methods. Given an input PhysicalPlan, it compiles it to get a MapReduce Plan. The MapReduce plan which has multiple MapReduce operators each one of which has to be run as a map reduce job with dependency information stored in the plan. It compiles the MROperPlan into a JobControl object. Each Map Reduce operator is converted into a Job and added to the JobControl object. Each Job also has a set of dependent Jobs that are created using the MROperPlan. The JobControl object is obtained from the JobControlCompiler Then a new thread is spawned that submits these jobs while respecting the dependency information. The parent thread monitors the submitted jobs' progress and after it is complete, stops the JobControl thread.

Specified by:
launchPig in class Launcher
Throws:
PlanException
VisitorException
IOException
ExecException
JobCreationException
Exception

explain

public void explain(PhysicalPlan php,
                    PigContext pc,
                    PrintStream ps,
                    String format,
                    boolean verbose)
             throws PlanException,
                    VisitorException,
                    IOException
Description copied from class: Launcher
Explain how a pig job will be executed on the underlying infrastructure.

Specified by:
explain in class Launcher
Parameters:
php - PhysicalPlan to explain
pc - PigContext to use for configuration
ps - PrintStream to write output on.
format - Format to write in
verbose - Amount of information to print
Throws:
VisitorException
IOException
PlanException


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