Package org.apache.sysds.utils

Class MemoryEstimates

  • public class MemoryEstimates
extends Object
    Memory Estimates is a helper class containing static classes that estimate the memory requirements of different types of objects in java. All estimates are worst case JVM x86-64bit uncompressed object pointers. This in practice means that the objects are most commonly smaller, for instance the object references are often time. If the memory pressure is low (there is a low number of allocated objects) then object pointers are 4 bits.

    • Constructor Summary

      Constructors 
      Constructor Description
      MemoryEstimates()  

    • Method Summary

      All Methods Static Methods Concrete Methods 
      Modifier and Type Method Description
      static double bitSetCost​(long length)
      Get the worst case memory usage of an java.util.BitSet java object.
      static double booleanArrayCost​(long length)
      Get the worst case memory usage of an array of booleans.
      static double byteArrayCost​(long length)
      Get the worst case memory usage of an array of bytes.
      static double charArrayCost​(long length)
      Get the worst case memory usage of an array of chars.
      static double doubleArrayCost​(long length)
      Get the worst case memory usage of an array of doubles.
      static double floatArrayCost​(long length)
      Get the worst case memory usage of an array of integers.
      static double intArrayCost​(long length)
      Get the worst case memory usage of an array of integers.
      static double longArrayCost​(long length)
      Get the worst case memory usage for an array of longs
      static double objectArrayCost​(long length)
      Get the worst case memory usage for an array of objects.
      static double stringArrayCost​(int length, int avgStringLength)  
      static double stringArrayCost​(String[] strings)
      Get the worst case memory usage of an array containing strings.
      static long stringCost​(long length)
      Get the worst case memory usage of a single string, assuming given length.
      static long stringCost​(String value)
      Get the worst case memory usage of a single string.

    • Constructor Detail

      • MemoryEstimates

        public MemoryEstimates()

    • Method Detail

      • bitSetCost

        public static double bitSetCost​(long length)
        Get the worst case memory usage of an java.util.BitSet java object.
        Parameters:
        length - The length of the array.
        Returns:
        The memory estimate in bytes

      • booleanArrayCost

        public static double booleanArrayCost​(long length)
        Get the worst case memory usage of an array of booleans. Unfortunately in java booleans are allocated as bytes.
        Parameters:
        length - The length of the array.
        Returns:
        The memory estimate in bytes.

      • byteArrayCost

        public static double byteArrayCost​(long length)
        Get the worst case memory usage of an array of bytes.
        Parameters:
        length - The length of the array.
        Returns:
        The memory estimate in bytes

      • charArrayCost

        public static double charArrayCost​(long length)
        Get the worst case memory usage of an array of chars.
        Parameters:
        length - The length of the array.
        Returns:
        The memory estimate in bytes

      • intArrayCost

        public static double intArrayCost​(long length)
        Get the worst case memory usage of an array of integers.
        Parameters:
        length - The length of the array.
        Returns:
        The memory estimate in bytes

      • floatArrayCost

        public static double floatArrayCost​(long length)
        Get the worst case memory usage of an array of integers.
        Parameters:
        length - The length of the array.
        Returns:
        The memory estimate in bytes.

      • doubleArrayCost

        public static final double doubleArrayCost​(long length)
        Get the worst case memory usage of an array of doubles.
        Parameters:
        length - The length of the array.
        Returns:
        The memory estimate in bytes

      • objectArrayCost

        public static final double objectArrayCost​(long length)
        Get the worst case memory usage for an array of objects. Note this does not take into account each objects allocated variables, just the objects themselves.
        Parameters:
        length - The length of the array.
        Returns:
        The memory estimate in bytes

      • longArrayCost

        public static final double longArrayCost​(long length)
        Get the worst case memory usage for an array of longs
        Parameters:
        length - The length of the array.
        Returns:
        The memory estimate in bytes

      • stringArrayCost

        public static final double stringArrayCost​(String[] strings)
        Get the worst case memory usage of an array containing strings. In case anyone is wondering ... strings are expensive.
        Parameters:
        strings - The strings array.
        Returns:
        The array memory cost

      • stringArrayCost

        public static final double stringArrayCost​(int length,
                                           int avgStringLength)

      • stringCost

        public static long stringCost​(String value)
        Get the worst case memory usage of a single string. In case anyone is wondering ... strings are expensive.
        Parameters:
        value - The String to measure
        Returns:
        The size in memory.

      • stringCost

        public static long stringCost​(long length)
        Get the worst case memory usage of a single string, assuming given length.
        Parameters:
        length - The length of the string
        Returns:
        The size in memory