org.apache.sysds.runtime.instructions.gpu.context

## Class GPUContextPool

- java.lang.Object
- - org.apache.sysds.runtime.instructions.gpu.context.GPUContextPool

-     public class GPUContextPool
      extends Object

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `static String` | `AVAILABLE_GPUS` GPUs to use, can specify -1 to use all, comma separated list of GPU numbers, a specific GPU or a range

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `GPUContextPool()`

  - ### Method Summary

    All Methods Static Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `static void` | `freeAllGPUContexts()` Unreserves all GPUContexts
    `static int` | `getAvailableCount()` Get the number of free GPUContexts
    `static int` | `getDeviceCount()` Number of available devices on this machine
    `static long` | `initialGPUMemBudget()` Gets the initial GPU memory budget.
    `static void` | `initializeGPU()` Static initialization of the number of devices Also sets behaviour for J{Cuda, Cudnn, Cublas, Cusparse} in case of error Initializes the CUDA driver All these need be done once, and not per GPU
    `static ArrayList<Integer>` | `parseListString(String str, int max)` Parses a string into a list.
    `static List<GPUContext>` | `reserveAllGPUContexts()` Reserves and gets an initialized list of GPUContexts

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

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

- - ### Field Detail

    - #### AVAILABLE_GPUS

          public static String AVAILABLE_GPUS

      GPUs to use, can specify -1 to use all, comma separated list of GPU numbers, a specific GPU or a range

  - ### Constructor Detail

    - #### GPUContextPool

          public GPUContextPool()

  - ### Method Detail

    - #### initializeGPU

          public static void initializeGPU()

      Static initialization of the number of devices Also sets behaviour for J{Cuda, Cudnn, Cublas, Cusparse} in case of error Initializes the CUDA driver All these need be done once, and not per GPU

    - #### parseListString

          public static ArrayList<Integer> parseListString(String str,
                                                           int max)

      Parses a string into a list. The string can be of these forms: 1. "-1" : all integers from range 0 to max - [0,1,2,3....max] 2. "2,3,0" : comma separated list of integers - [0,2,3] 3. "4" : a specific integer - [4] 4. "0-4" : a range of integers - [0,1,2,3,4] In ranges and comma separated lists, all values must be positive. Anything else is invalid.
      Parameters:
        `str` - input string
        `max` - maximum range of integers
      Returns:
        the list of integers in the parsed string

    - #### reserveAllGPUContexts

          public static List<GPUContext> reserveAllGPUContexts()

      Reserves and gets an initialized list of GPUContexts
      Returns:
        null if no GPUContexts in pool, otherwise a valid list of GPUContext

    - #### getAvailableCount

          public static int getAvailableCount()

      Get the number of free GPUContexts
      Returns:
        number of free GPUContexts

    - #### getDeviceCount

          public static int getDeviceCount()

      Number of available devices on this machine
      Returns:
        number of available GPUs on this machine

    - #### freeAllGPUContexts

          public static void freeAllGPUContexts()

      Unreserves all GPUContexts

    - #### initialGPUMemBudget

          public static long initialGPUMemBudget()
                                          throws RuntimeException

      Gets the initial GPU memory budget. This is the minimum of the available memories across all the GPUs on the machine(s)
      Returns:
        minimum available memory
      Throws:
        `RuntimeException` - if error initializing the GPUs

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