org.apache.hadoop.mapred
Interface Reporter

All Superinterfaces:
Progressable

@InterfaceAudience.Public
@InterfaceStability.Stable
public interface Reporter
extends Progressable

A facility for Map-Reduce applications to report progress and update counters, status information etc.

Mapper and Reducer can use the Reporter provided to report progress or just indicate that they are alive. In scenarios where the application takes an insignificant amount of time to process individual key/value pairs, this is crucial since the framework might assume that the task has timed-out and kill that task.

Applications can also update Counters via the provided Reporter .

See Also:
Progressable, Counters

Field Summary
static Reporter NULL
          A constant of Reporter type that does nothing.
 
Method Summary
 org.apache.hadoop.mapred.Counters.Counter getCounter(Enum<?> name)
          Get the Counters.Counter of the given group with the given name.
 org.apache.hadoop.mapred.Counters.Counter getCounter(String group, String name)
          Get the Counters.Counter of the given group with the given name.
 InputSplit getInputSplit()
          Get the InputSplit object for a map.
 float getProgress()
          Get the progress of the task.
 void incrCounter(Enum<?> key, long amount)
          Increments the counter identified by the key, which can be of any Enum type, by the specified amount.
 void incrCounter(String group, String counter, long amount)
          Increments the counter identified by the group and counter name by the specified amount.
 void setStatus(String status)
          Set the status description for the task.
 
Methods inherited from interface org.apache.hadoop.util.Progressable
progress
 

Field Detail

NULL

static final Reporter NULL
A constant of Reporter type that does nothing.

Method Detail

setStatus

void setStatus(String status)
Set the status description for the task.

Parameters:
status - brief description of the current status.

getCounter

org.apache.hadoop.mapred.Counters.Counter getCounter(Enum<?> name)
Get the Counters.Counter of the given group with the given name.

Parameters:
name - counter name
Returns:
the Counter of the given group/name.

getCounter

org.apache.hadoop.mapred.Counters.Counter getCounter(String group,
                                                     String name)
Get the Counters.Counter of the given group with the given name.

Parameters:
group - counter group
name - counter name
Returns:
the Counter of the given group/name.

incrCounter

void incrCounter(Enum<?> key,
                 long amount)
Increments the counter identified by the key, which can be of any Enum type, by the specified amount.

Parameters:
key - key to identify the counter to be incremented. The key can be be any Enum.
amount - A non-negative amount by which the counter is to be incremented.

incrCounter

void incrCounter(String group,
                 String counter,
                 long amount)
Increments the counter identified by the group and counter name by the specified amount.

Parameters:
group - name to identify the group of the counter to be incremented.
counter - name to identify the counter within the group.
amount - A non-negative amount by which the counter is to be incremented.

getInputSplit

InputSplit getInputSplit()
                         throws UnsupportedOperationException
Get the InputSplit object for a map.

Returns:
the InputSplit that the map is reading from.
Throws:
UnsupportedOperationException - if called outside a mapper

getProgress

float getProgress()
Get the progress of the task. Progress is represented as a number between 0 and 1 (inclusive).



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