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## org.apache.hadoop.mapred
Class JobClient

    java.lang.Object
      org.apache.hadoop.conf.Configured
          org.apache.hadoop.mapred.JobClient

All Implemented Interfaces:
  Configurable, Tool

    public class JobClient

extends Configured
implements Tool

`JobClient` is the primary interface for the user-job to interact with the `JobTracker`. `JobClient` provides facilities to submit jobs, track their progress, access component-tasks' reports/logs, get the Map-Reduce cluster status information etc.

The job submission process involves:

1. Checking the input and output specifications of the job.
2. Computing the `InputSplit`s for the job.
3. Setup the requisite accounting information for the `DistributedCache` of the job, if necessary.
4. Copying the job's jar and configuration to the map-reduce system directory on the distributed file-system.
5. Submitting the job to the `JobTracker` and optionally monitoring it's status.

Normally the user creates the application, describes various facets of the job via `JobConf` and then uses the `JobClient` to submit the job and monitor its progress.

Here is an example on how to use `JobClient`:

>          // Create a new JobConf
>          JobConf job = new JobConf(new Configuration(), MyJob.class);

>          // Specify various job-specific parameters
>          job.setJobName("myjob");

>          job.setInputPath(new Path("in"));
>          job.setOutputPath(new Path("out"));

>          job.setMapperClass(MyJob.MyMapper.class);
>          job.setReducerClass(MyJob.MyReducer.class);

>          // Submit the job, then poll for progress until the job is complete
>          JobClient.runJob(job);

#### Job Control

At times clients would chain map-reduce jobs to accomplish complex tasks which cannot be done via a single map-reduce job. This is fairly easy since the output of the job, typically, goes to distributed file-system and that can be used as the input for the next job.

However, this also means that the onus on ensuring jobs are complete (success/failure) lies squarely on the clients. In such situations the various job-control options are:

1. `runJob(JobConf)` : submits the job and returns only after the job has completed.
2. `submitJob(JobConf)` : only submits the job, then poll the returned handle to the `RunningJob` to query status and make scheduling decisions.
3. `JobConf.setJobEndNotificationURI(String)` : setup a notification on job-completion, thus avoiding polling.

See Also:
  `JobConf`, `ClusterStatus`, `Tool`, `DistributedCache`

Nested Class Summary
`static class` | `JobClient.TaskStatusFilter`

Field Summary
`static int` | `CLUSTER_INCREMENT`
`static long` | `COUNTER_UPDATE_INTERVAL`
`static int` | `FILE_NOT_FOUND`
`static String` | `FOR_REDUCE_TASK` The reduce task number for which this map output is being transferred
`static String` | `FROM_MAP_TASK` The map task from which the map output data is being transferred
`static int` | `HEARTBEAT_INTERVAL_MIN`
`static String` | `MAP_OUTPUT_LENGTH` The custom http header used for the map output length.
`static String` | `RAW_MAP_OUTPUT_LENGTH` The custom http header used for the "raw" map output length.
`static int` | `SUCCESS`
`static String` | `WORKDIR`

Constructor Summary
`JobClient()` Create a job client.
`JobClient(InetSocketAddress jobTrackAddr, Configuration conf)` Build a job client, connect to the indicated job tracker.
`JobClient(JobConf conf)` Build a job client with the given `JobConf`, and connect to the default `JobTracker`.

Method Summary
`void` | `close()` Close the `JobClient`.
`void` | `displayTasks(JobID jobId, String type, String state)` Display the information about a job's tasks, of a particular type and in a particular state
`JobStatus[]` | `getAllJobs()` Get the jobs that are submitted.
`TaskReport[]` | `getCleanupTaskReports(JobID jobId)` Get the information of the current state of the cleanup tasks of a job.
`ClusterStatus` | `getClusterStatus()` Get status information about the Map-Reduce cluster.
`ClusterStatus` | `getClusterStatus(boolean detailed)` Get status information about the Map-Reduce cluster.
`int` | `getDefaultMaps()` Get status information about the max available Maps in the cluster.
`int` | `getDefaultReduces()` Get status information about the max available Reduces in the cluster.
`FileSystem` | `getFs()` Get a filesystem handle.
`RunningJob` | `getJob(JobID jobid)` Get an `RunningJob` object to track an ongoing job.
`RunningJob` | `getJob(String jobid)` Deprecated. Applications should rather use `getJob(JobID)`.
`JobStatus[]` | `getJobsFromQueue(String queueName)` Gets all the jobs which were added to particular Job Queue
`TaskReport[]` | `getMapTaskReports(JobID jobId)` Get the information of the current state of the map tasks of a job.
`TaskReport[]` | `getMapTaskReports(String jobId)` Deprecated. Applications should rather use `getMapTaskReports(JobID)`
`JobQueueInfo` | `getQueueInfo(String queueName)` Gets the queue information associated to a particular Job Queue
`JobQueueInfo[]` | `getQueues()` Return an array of queue information objects about all the Job Queues configured.
`TaskReport[]` | `getReduceTaskReports(JobID jobId)` Get the information of the current state of the reduce tasks of a job.
`TaskReport[]` | `getReduceTaskReports(String jobId)` Deprecated. Applications should rather use `getReduceTaskReports(JobID)`
`TaskReport[]` | `getSetupTaskReports(JobID jobId)` Get the information of the current state of the setup tasks of a job.
`Path` | `getSystemDir()` Grab the jobtracker system directory path where job-specific files are to be placed.
`JobClient.TaskStatusFilter` | `getTaskOutputFilter()` Deprecated.
`static JobClient.TaskStatusFilter` | `getTaskOutputFilter(JobConf job)` Get the task output filter out of the JobConf.
`void` | `init(JobConf conf)` Connect to the default `JobTracker`.
`static boolean` | `isJobDirValid(Path jobDirPath, FileSystem fs)` Checks if the job directory is clean and has all the required components for (re) starting the job
`JobStatus[]` | `jobsToComplete()` Get the jobs that are not completed and not failed.
`static void` | `main(String[] argv)`
`boolean` | `monitorAndPrintJob(JobConf conf, RunningJob job)` Monitor a job and print status in real-time as progress is made and tasks fail.
`int` | `run(String[] argv)` Execute the command with the given arguments.
`static RunningJob` | `runJob(JobConf job)` Utility that submits a job, then polls for progress until the job is complete.
`void` | `setTaskOutputFilter(JobClient.TaskStatusFilter newValue)` Deprecated.
`static void` | `setTaskOutputFilter(JobConf job, JobClient.TaskStatusFilter newValue)` Modify the JobConf to set the task output filter.
`RunningJob` | `submitJob(JobConf job)` Submit a job to the MR system.
`RunningJob` | `submitJob(String jobFile)` Submit a job to the MR system.
`RunningJob` | `submitJobInternal(JobConf job)` Internal method for submitting jobs to the system.

Methods inherited from class org.apache.hadoop.conf.Configured
`getConf, setConf`

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Methods inherited from interface org.apache.hadoop.conf.Configurable
`getConf, setConf`

Field Detail

### HEARTBEAT_INTERVAL_MIN

    public static final int HEARTBEAT_INTERVAL_MIN

See Also:
  Constant Field Values

### CLUSTER_INCREMENT

    public static final int CLUSTER_INCREMENT

See Also:
  Constant Field Values

### COUNTER_UPDATE_INTERVAL

    public static final long COUNTER_UPDATE_INTERVAL

See Also:
  Constant Field Values

### SUCCESS

    public static final int SUCCESS

See Also:
  Constant Field Values

### FILE_NOT_FOUND

    public static final int FILE_NOT_FOUND

See Also:
  Constant Field Values

### MAP_OUTPUT_LENGTH

    public static final String MAP_OUTPUT_LENGTH

  The custom http header used for the map output length.

  See Also:
    Constant Field Values

### RAW_MAP_OUTPUT_LENGTH

    public static final String RAW_MAP_OUTPUT_LENGTH

  The custom http header used for the "raw" map output length.

  See Also:
    Constant Field Values

### FROM_MAP_TASK

    public static final String FROM_MAP_TASK

  The map task from which the map output data is being transferred

  See Also:
    Constant Field Values

### FOR_REDUCE_TASK

    public static final String FOR_REDUCE_TASK

  The reduce task number for which this map output is being transferred

  See Also:
    Constant Field Values

### WORKDIR

    public static final String WORKDIR

See Also:
  Constant Field Values

Constructor Detail

### JobClient

    public JobClient()

  Create a job client.

### JobClient

    public JobClient(JobConf conf)
              throws IOException

  Build a job client with the given `JobConf`, and connect to the default `JobTracker`.

  Parameters:
    `conf` - the job configuration.
  Throws:
    `IOException`

### JobClient

    public JobClient(InetSocketAddress jobTrackAddr,
                     Configuration conf)
              throws IOException

  Build a job client, connect to the indicated job tracker.

  Parameters:
    `jobTrackAddr` - the job tracker to connect to.
    `conf` - configuration.
  Throws:
    `IOException`

Method Detail

### init

    public void init(JobConf conf)
              throws IOException

  Connect to the default `JobTracker`.

  Parameters:
    `conf` - the job configuration.
  Throws:
    `IOException`

### close

    public void close()
               throws IOException

  Close the `JobClient`.

  Throws:
    `IOException`

### getFs

    public FileSystem getFs()
                     throws IOException

  Get a filesystem handle. We need this to prepare jobs for submission to the MapReduce system.

  Returns:
    the filesystem handle.
  Throws:
    `IOException`

### submitJob

    public RunningJob submitJob(String jobFile)
                         throws FileNotFoundException,
                                InvalidJobConfException,
                                IOException

  Submit a job to the MR system. This returns a handle to the `RunningJob` which can be used to track the running-job.

  Parameters:
    `jobFile` - the job configuration.
  Returns:
    a handle to the `RunningJob` which can be used to track the running-job.
  Throws:
    `FileNotFoundException`
    `InvalidJobConfException`
    `IOException`

### submitJob

    public RunningJob submitJob(JobConf job)
                         throws FileNotFoundException,
                                IOException

  Submit a job to the MR system. This returns a handle to the `RunningJob` which can be used to track the running-job.

  Parameters:
    `job` - the job configuration.
  Returns:
    a handle to the `RunningJob` which can be used to track the running-job.
  Throws:
    `FileNotFoundException`
    `IOException`

### submitJobInternal

    public RunningJob submitJobInternal(JobConf job)
                                 throws FileNotFoundException,
                                        ClassNotFoundException,
                                        InterruptedException,
                                        IOException

  Internal method for submitting jobs to the system.

  Parameters:
    `job` - the configuration to submit
  Returns:
    a proxy object for the running job
  Throws:
    `FileNotFoundException`
    `ClassNotFoundException`
    `InterruptedException`
    `IOException`

### isJobDirValid

    public static boolean isJobDirValid(Path jobDirPath,
                                        FileSystem fs)
                                 throws IOException

  Checks if the job directory is clean and has all the required components for (re) starting the job

  Throws:
    `IOException`

### getJob

    public RunningJob getJob(JobID jobid)
                      throws IOException

  Get an `RunningJob` object to track an ongoing job. Returns null if the id does not correspond to any known job.

  Parameters:
    `jobid` - the jobid of the job.
  Returns:
    the `RunningJob` handle to track the job, null if the `jobid` doesn't correspond to any known job.
  Throws:
    `IOException`

### getJob

    @Deprecated
    public RunningJob getJob(String jobid)
                      throws IOException

  Deprecated. Applications should rather use `getJob(JobID)`.

  Throws:
    `IOException`

### getMapTaskReports

    public TaskReport[] getMapTaskReports(JobID jobId)
                                   throws IOException

  Get the information of the current state of the map tasks of a job.

  Parameters:
    `jobId` - the job to query.
  Returns:
    the list of all of the map tips.
  Throws:
    `IOException`

### getMapTaskReports

    @Deprecated
    public TaskReport[] getMapTaskReports(String jobId)
                                   throws IOException

  Deprecated. Applications should rather use `getMapTaskReports(JobID)`

  Throws:
    `IOException`

### getReduceTaskReports

    public TaskReport[] getReduceTaskReports(JobID jobId)
                                      throws IOException

  Get the information of the current state of the reduce tasks of a job.

  Parameters:
    `jobId` - the job to query.
  Returns:
    the list of all of the reduce tips.
  Throws:
    `IOException`

### getCleanupTaskReports

    public TaskReport[] getCleanupTaskReports(JobID jobId)
                                       throws IOException

  Get the information of the current state of the cleanup tasks of a job.

  Parameters:
    `jobId` - the job to query.
  Returns:
    the list of all of the cleanup tips.
  Throws:
    `IOException`

### getSetupTaskReports

    public TaskReport[] getSetupTaskReports(JobID jobId)
                                     throws IOException

  Get the information of the current state of the setup tasks of a job.

  Parameters:
    `jobId` - the job to query.
  Returns:
    the list of all of the setup tips.
  Throws:
    `IOException`

### getReduceTaskReports

    @Deprecated
    public TaskReport[] getReduceTaskReports(String jobId)
                                      throws IOException

  Deprecated. Applications should rather use `getReduceTaskReports(JobID)`

  Throws:
    `IOException`

### displayTasks

    public void displayTasks(JobID jobId,
                             String type,
                             String state)
                      throws IOException

  Display the information about a job's tasks, of a particular type and in a particular state

  Parameters:
    `jobId` - the ID of the job
    `type` - the type of the task (map/reduce/setup/cleanup)
    `state` - the state of the task (pending/running/completed/failed/killed)
  Throws:
    `IOException`

### getClusterStatus

    public ClusterStatus getClusterStatus()
                                   throws IOException

  Get status information about the Map-Reduce cluster.

  Returns:
    the status information about the Map-Reduce cluster as an object of `ClusterStatus`.
  Throws:
    `IOException`

### getClusterStatus

    public ClusterStatus getClusterStatus(boolean detailed)
                                   throws IOException

  Get status information about the Map-Reduce cluster.

  Parameters:
    `detailed` - if true then get a detailed status including the tracker names
  Returns:
    the status information about the Map-Reduce cluster as an object of `ClusterStatus`.
  Throws:
    `IOException`

### jobsToComplete

    public JobStatus[] jobsToComplete()
                               throws IOException

  Get the jobs that are not completed and not failed.

  Returns:
    array of `JobStatus` for the running/to-be-run jobs.
  Throws:
    `IOException`

### getAllJobs

    public JobStatus[] getAllJobs()
                           throws IOException

  Get the jobs that are submitted.

  Returns:
    array of `JobStatus` for the submitted jobs.
  Throws:
    `IOException`

### runJob

    public static RunningJob runJob(JobConf job)
                             throws IOException

  Utility that submits a job, then polls for progress until the job is complete.

  Parameters:
    `job` - the job configuration.
  Throws:
    `IOException` - if the job fails

### monitorAndPrintJob

    public boolean monitorAndPrintJob(JobConf conf,
                                      RunningJob job)
                               throws IOException,
                                      InterruptedException

  Monitor a job and print status in real-time as progress is made and tasks fail.

  Parameters:
    `conf` - the job's configuration
    `job` - the job to track
  Returns:
    true if the job succeeded
  Throws:
    `IOException` - if communication to the JobTracker fails
    `InterruptedException`

### setTaskOutputFilter

    @Deprecated
    public void setTaskOutputFilter(JobClient.TaskStatusFilter newValue)

  Deprecated.

  Sets the output filter for tasks. only those tasks are printed whose output matches the filter.

  Parameters:
    `newValue` - task filter.

### getTaskOutputFilter

    public static JobClient.TaskStatusFilter getTaskOutputFilter(JobConf job)

  Get the task output filter out of the JobConf.

  Parameters:
    `job` - the JobConf to examine.
  Returns:
    the filter level.

### setTaskOutputFilter

    public static void setTaskOutputFilter(JobConf job,
                                           JobClient.TaskStatusFilter newValue)

  Modify the JobConf to set the task output filter.

  Parameters:
    `job` - the JobConf to modify.
    `newValue` - the value to set.

### getTaskOutputFilter

    @Deprecated
    public JobClient.TaskStatusFilter getTaskOutputFilter()

  Deprecated.

  Returns task output filter.

  Returns:
    task filter.

### run

    public int run(String[] argv)
            throws Exception

  Description copied from interface: `Tool`
  Execute the command with the given arguments.

  Specified by:
    `run` in interface `Tool`
  Parameters:
    `argv` - command specific arguments.
  Returns:
    exit code.
  Throws:
    `Exception`

### getDefaultMaps

    public int getDefaultMaps()
                       throws IOException

  Get status information about the max available Maps in the cluster.

  Returns:
    the max available Maps in the cluster
  Throws:
    `IOException`

### getDefaultReduces

    public int getDefaultReduces()
                          throws IOException

  Get status information about the max available Reduces in the cluster.

  Returns:
    the max available Reduces in the cluster
  Throws:
    `IOException`

### getSystemDir

    public Path getSystemDir()

  Grab the jobtracker system directory path where job-specific files are to be placed.

  Returns:
    the system directory where job-specific files are to be placed.

### getQueues

    public JobQueueInfo[] getQueues()
                             throws IOException

  Return an array of queue information objects about all the Job Queues configured.

  Returns:
    Array of JobQueueInfo objects
  Throws:
    `IOException`

### getJobsFromQueue

    public JobStatus[] getJobsFromQueue(String queueName)
                                 throws IOException

  Gets all the jobs which were added to particular Job Queue

  Parameters:
    `queueName` - name of the Job Queue
  Returns:
    Array of jobs present in the job queue
  Throws:
    `IOException`

### getQueueInfo

    public JobQueueInfo getQueueInfo(String queueName)
                              throws IOException

  Gets the queue information associated to a particular Job Queue

  Parameters:
    `queueName` - name of the job queue.
  Returns:
    Queue information associated to particular queue.
  Throws:
    `IOException`

### main

    public static void main(String[] argv)
                     throws Exception

  Throws:
    `Exception`

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