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 significant 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

Fields

Modifier and Type	Field and Description
static Reporter	NULL A constant of Reporter type that does nothing.

Method Summary

Methods

Modifier and Type	Method and Description
Counters.Counter	getCounter(Enum<?> name) Get the Counters.Counter of the given group with the given name.
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

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

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).