ml.dmlc.xgboost4j.java

## Class Rabit

- java.lang.Object
- - ml.dmlc.xgboost4j.java.Rabit

-     public class Rabit
      extends Object

  Rabit global class for synchronization.

- - ### Nested Class Summary

    Nested Classes
    Modifier and Type | Class and Description
    --- | ---
    `static class` | `Rabit.DataType`
    `static class` | `Rabit.OpType`

  - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `static List<String>` | `mockList`
    `static Map<String,String>` | `rabitEnvs`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `Rabit()`

  - ### Method Summary

    All Methods Static Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `static float[]` | `allReduce(float[] elements, Rabit.OpType op)` perform Allreduce on distributed float vectors using operator op.
    `static int` | `getRank()` get rank of current thread.
    `static int` | `getWorldSize()` get world size of current job.
    `static void` | `init(Map<String,String> envs)` Initialize the rabit library on current working thread.
    `static void` | `shutdown()` Shutdown the rabit engine in current working thread, equals to finalize.
    `static void` | `trackerPrint(String msg)` Print the message on rabit tracker.
    `static int` | `versionNumber()` Get version number of current stored model in the thread.

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- - ### Field Detail

    - #### rabitEnvs

          public static Map<String,String> rabitEnvs

    - #### mockList

          public static List<String> mockList

  - ### Constructor Detail

    - #### Rabit

          public Rabit()

  - ### Method Detail

    - #### init

          public static void init(Map<String,String> envs)
                           throws XGBoostError

      Initialize the rabit library on current working thread.
      Parameters:
        `envs` - The additional environment variables to pass to rabit.
      Throws:
        `XGBoostError`

    - #### shutdown

          public static void shutdown()
                               throws XGBoostError

      Shutdown the rabit engine in current working thread, equals to finalize.
      Throws:
        `XGBoostError`

    - #### trackerPrint

          public static void trackerPrint(String msg)
                                   throws XGBoostError

      Print the message on rabit tracker.
      Parameters:
        `msg` -
      Throws:
        `XGBoostError`

    - #### versionNumber

          public static int versionNumber()
                                   throws XGBoostError

      Get version number of current stored model in the thread. which means how many calls to CheckPoint we made so far.
      Returns:
        version Number.
      Throws:
        `XGBoostError`

    - #### getRank

          public static int getRank()
                             throws XGBoostError

      get rank of current thread.
      Returns:
        the rank.
      Throws:
        `XGBoostError`

    - #### getWorldSize

          public static int getWorldSize()
                                  throws XGBoostError

      get world size of current job.
      Returns:
        the worldsize
      Throws:
        `XGBoostError`

    - #### allReduce

          public static float[] allReduce(float[] elements,
                                          Rabit.OpType op)

      perform Allreduce on distributed float vectors using operator op. This implementation of allReduce does not support customized prepare function callback in the native code, as this function is meant for testing purposes only (to test the Rabit tracker.)
      Parameters:
        `elements` - local elements on distributed workers.
        `op` - operator used for Allreduce.
      Returns:
        All-reduced float elements according to the given operator.

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