Package org.apache.lucene.util
Class RamUsageEstimator
- java.lang.Object
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- org.apache.lucene.util.RamUsageEstimator
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public final class RamUsageEstimator extends Object
Estimates the size (memory representation) of Java objects.This class uses assumptions that were discovered for the Hotspot virtual machine. If you use a non-OpenJDK/Oracle-based JVM, the measurements may be slightly wrong.
- See Also:
shallowSizeOf(Object),shallowSizeOfInstance(Class)- NOTE: This API is for internal purposes only and might change in incompatible ways in the next release.
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Field Summary
Fields Modifier and Type Field Description static booleanCOMPRESSED_REFS_ENABLEDTrue, iff compressed references (oops) are enabled by this JVMstatic longHASHTABLE_RAM_BYTES_PER_ENTRYApproximate memory usage that we assign to a Hashtable / HashMap entry.static longLINKED_HASHTABLE_RAM_BYTES_PER_ENTRYApproximate memory usage that we assign to a LinkedHashMap entry.static intMAX_DEPTHRecurse only into immediate descendants.static intNUM_BYTES_ARRAY_HEADERNumber of bytes to represent an array header (no content, but with alignments).static intNUM_BYTES_OBJECT_ALIGNMENTA constant specifying the object alignment boundary inside the JVM.static intNUM_BYTES_OBJECT_HEADERNumber of bytes to represent an object header (no fields, no alignments).static intNUM_BYTES_OBJECT_REFNumber of bytes this JVM uses to represent an object reference.static longONE_GBOne gigabyte bytes.static longONE_KBOne kilobyte bytes.static longONE_MBOne megabyte bytes.static Map<Class<?>,Integer>primitiveSizesSizes of primitive classes.static intQUERY_DEFAULT_RAM_BYTES_USEDApproximate memory usage that we assign to all unknown queries - this maps roughly to a BooleanQuery with a couple term clauses.static intUNKNOWN_DEFAULT_RAM_BYTES_USEDApproximate memory usage that we assign to all unknown objects - this maps roughly to a few primitive fields and a couple short String-s.
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Method Summary
All Methods Static Methods Concrete Methods Modifier and Type Method Description static longadjustForField(long sizeSoFar, Field f)This method returns the maximum representation size of an object.static longalignObjectSize(long size)Aligns an object size to be the next multiple ofNUM_BYTES_OBJECT_ALIGNMENT.static StringhumanReadableUnits(long bytes)Returnssizein human-readable units (GB, MB, KB or bytes).static StringhumanReadableUnits(long bytes, DecimalFormat df)Returnssizein human-readable units (GB, MB, KB or bytes).static longshallowSizeOf(boolean[] arr)Returns the size in bytes of the boolean[] object.static longshallowSizeOf(byte[] arr)Returns the size in bytes of the byte[] object.static longshallowSizeOf(char[] arr)Returns the size in bytes of the char[] object.static longshallowSizeOf(double[] arr)Returns the size in bytes of the double[] object.static longshallowSizeOf(float[] arr)Returns the size in bytes of the float[] object.static longshallowSizeOf(int[] arr)Returns the size in bytes of the int[] object.static longshallowSizeOf(long[] arr)Returns the size in bytes of the long[] object.static longshallowSizeOf(short[] arr)Returns the size in bytes of the short[] object.static longshallowSizeOf(Object obj)Estimates a "shallow" memory usage of the given object.static longshallowSizeOf(Object[] arr)Returns the shallow size in bytes of the Object[] object.static longshallowSizeOfInstance(Class<?> clazz)Returns the shallow instance size in bytes an instance of the given class would occupy.static longsizeOf(boolean[] arr)Returns the size in bytes of the boolean[] object.static longsizeOf(byte[] arr)Returns the size in bytes of the byte[] object.static longsizeOf(char[] arr)Returns the size in bytes of the char[] object.static longsizeOf(double[] arr)Returns the size in bytes of the double[] object.static longsizeOf(float[] arr)Returns the size in bytes of the float[] object.static longsizeOf(int[] arr)Returns the size in bytes of the int[] object.static longsizeOf(long[] arr)Returns the size in bytes of the long[] object.static longsizeOf(short[] arr)Returns the size in bytes of the short[] object.static longsizeOf(Integer ignored)Return the shallow size of the providedIntegerobject.static longsizeOf(Long ignored)Return the shallow size of the providedLongobject.static longsizeOf(String s)Returns the size in bytes of the String object.static longsizeOf(String[] arr)Returns the size in bytes of the String[] object.static longsizeOf(Query q)Returns the size in bytes of a Query object.static longsizeOf(Query q, long defSize)Returns the size in bytes of a Query object.static longsizeOf(Accountable accountable)Returns the size in bytes of theAccountableobject, using itsAccountable.ramBytesUsed()method.static longsizeOf(Accountable[] accountables)Return the size of the provided array ofAccountables by summing up the shallow size of the array and thememory usagereported by eachAccountable.static longsizeOfCollection(Collection<?> collection)Returns the size in bytes of a Collection object, including sizes of its values, supplyingUNKNOWN_DEFAULT_RAM_BYTES_USEDwhen object type is not well known.static longsizeOfCollection(Collection<?> collection, long defSize)Returns the size in bytes of a Collection object, including sizes of its values, supplying default object size when object type is not well known.static longsizeOfMap(Map<?,?> map)Returns the size in bytes of a Map object, including sizes of its keys and values, supplyingUNKNOWN_DEFAULT_RAM_BYTES_USEDwhen object type is not well known.static longsizeOfMap(Map<?,?> map, long defSize)Returns the size in bytes of a Map object, including sizes of its keys and values, supplying default object size when object type is not well known.static longsizeOfObject(Object o)Best effort attempt to estimate the size in bytes of an undetermined object.static longsizeOfObject(Object o, long defSize)Best effort attempt to estimate the size in bytes of an undetermined object.
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Field Detail
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ONE_KB
public static final long ONE_KB
One kilobyte bytes.- See Also:
- Constant Field Values
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ONE_MB
public static final long ONE_MB
One megabyte bytes.- See Also:
- Constant Field Values
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ONE_GB
public static final long ONE_GB
One gigabyte bytes.- See Also:
- Constant Field Values
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COMPRESSED_REFS_ENABLED
public static final boolean COMPRESSED_REFS_ENABLED
True, iff compressed references (oops) are enabled by this JVM
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NUM_BYTES_OBJECT_REF
public static final int NUM_BYTES_OBJECT_REF
Number of bytes this JVM uses to represent an object reference.
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NUM_BYTES_OBJECT_HEADER
public static final int NUM_BYTES_OBJECT_HEADER
Number of bytes to represent an object header (no fields, no alignments).
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NUM_BYTES_ARRAY_HEADER
public static final int NUM_BYTES_ARRAY_HEADER
Number of bytes to represent an array header (no content, but with alignments).
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NUM_BYTES_OBJECT_ALIGNMENT
public static final int NUM_BYTES_OBJECT_ALIGNMENT
A constant specifying the object alignment boundary inside the JVM. Objects will always take a full multiple of this constant, possibly wasting some space.
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QUERY_DEFAULT_RAM_BYTES_USED
public static final int QUERY_DEFAULT_RAM_BYTES_USED
Approximate memory usage that we assign to all unknown queries - this maps roughly to a BooleanQuery with a couple term clauses.- See Also:
- Constant Field Values
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UNKNOWN_DEFAULT_RAM_BYTES_USED
public static final int UNKNOWN_DEFAULT_RAM_BYTES_USED
Approximate memory usage that we assign to all unknown objects - this maps roughly to a few primitive fields and a couple short String-s.- See Also:
- Constant Field Values
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primitiveSizes
public static final Map<Class<?>,Integer> primitiveSizes
Sizes of primitive classes.
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HASHTABLE_RAM_BYTES_PER_ENTRY
public static final long HASHTABLE_RAM_BYTES_PER_ENTRY
Approximate memory usage that we assign to a Hashtable / HashMap entry.
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LINKED_HASHTABLE_RAM_BYTES_PER_ENTRY
public static final long LINKED_HASHTABLE_RAM_BYTES_PER_ENTRY
Approximate memory usage that we assign to a LinkedHashMap entry.
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MAX_DEPTH
public static final int MAX_DEPTH
Recurse only into immediate descendants.- See Also:
- Constant Field Values
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Method Detail
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alignObjectSize
public static long alignObjectSize(long size)
Aligns an object size to be the next multiple ofNUM_BYTES_OBJECT_ALIGNMENT.
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sizeOf
public static long sizeOf(Integer ignored)
Return the shallow size of the providedIntegerobject. Ignores the possibility that this object is part of the VM IntegerCache
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sizeOf
public static long sizeOf(Long ignored)
Return the shallow size of the providedLongobject. Ignores the possibility that this object is part of the VM LongCache
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sizeOf
public static long sizeOf(byte[] arr)
Returns the size in bytes of the byte[] object.
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sizeOf
public static long sizeOf(boolean[] arr)
Returns the size in bytes of the boolean[] object.
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sizeOf
public static long sizeOf(char[] arr)
Returns the size in bytes of the char[] object.
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sizeOf
public static long sizeOf(short[] arr)
Returns the size in bytes of the short[] object.
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sizeOf
public static long sizeOf(int[] arr)
Returns the size in bytes of the int[] object.
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sizeOf
public static long sizeOf(float[] arr)
Returns the size in bytes of the float[] object.
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sizeOf
public static long sizeOf(long[] arr)
Returns the size in bytes of the long[] object.
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sizeOf
public static long sizeOf(double[] arr)
Returns the size in bytes of the double[] object.
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sizeOf
public static long sizeOf(String[] arr)
Returns the size in bytes of the String[] object.
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sizeOfMap
public static long sizeOfMap(Map<?,?> map)
Returns the size in bytes of a Map object, including sizes of its keys and values, supplyingUNKNOWN_DEFAULT_RAM_BYTES_USEDwhen object type is not well known. This method recurses up toMAX_DEPTH.
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sizeOfMap
public static long sizeOfMap(Map<?,?> map, long defSize)
Returns the size in bytes of a Map object, including sizes of its keys and values, supplying default object size when object type is not well known. This method recurses up toMAX_DEPTH.
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sizeOfCollection
public static long sizeOfCollection(Collection<?> collection)
Returns the size in bytes of a Collection object, including sizes of its values, supplyingUNKNOWN_DEFAULT_RAM_BYTES_USEDwhen object type is not well known. This method recurses up toMAX_DEPTH.
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sizeOfCollection
public static long sizeOfCollection(Collection<?> collection, long defSize)
Returns the size in bytes of a Collection object, including sizes of its values, supplying default object size when object type is not well known. This method recurses up toMAX_DEPTH.
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sizeOf
public static long sizeOf(Query q)
Returns the size in bytes of a Query object. Unknown query types will be estimated asQUERY_DEFAULT_RAM_BYTES_USED.
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sizeOf
public static long sizeOf(Query q, long defSize)
Returns the size in bytes of a Query object. Unknown query types will be estimated usingshallowSizeOf(Object), or using the supplieddefSizeparameter if its value is greater than 0.
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sizeOfObject
public static long sizeOfObject(Object o)
Best effort attempt to estimate the size in bytes of an undetermined object. Known types will be estimated according to their formulas, and all other object sizes will be estimated asUNKNOWN_DEFAULT_RAM_BYTES_USED.
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sizeOfObject
public static long sizeOfObject(Object o, long defSize)
Best effort attempt to estimate the size in bytes of an undetermined object. Known types will be estimated according to their formulas, and all other object sizes will be estimated usingshallowSizeOf(Object), or using the supplieddefSizeparameter if its value is greater than 0.
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sizeOf
public static long sizeOf(Accountable accountable)
Returns the size in bytes of theAccountableobject, using itsAccountable.ramBytesUsed()method.
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sizeOf
public static long sizeOf(String s)
Returns the size in bytes of the String object.
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shallowSizeOf
public static long shallowSizeOf(byte[] arr)
Returns the size in bytes of the byte[] object.
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shallowSizeOf
public static long shallowSizeOf(boolean[] arr)
Returns the size in bytes of the boolean[] object.
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shallowSizeOf
public static long shallowSizeOf(char[] arr)
Returns the size in bytes of the char[] object.
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shallowSizeOf
public static long shallowSizeOf(short[] arr)
Returns the size in bytes of the short[] object.
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shallowSizeOf
public static long shallowSizeOf(int[] arr)
Returns the size in bytes of the int[] object.
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shallowSizeOf
public static long shallowSizeOf(float[] arr)
Returns the size in bytes of the float[] object.
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shallowSizeOf
public static long shallowSizeOf(long[] arr)
Returns the size in bytes of the long[] object.
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shallowSizeOf
public static long shallowSizeOf(double[] arr)
Returns the size in bytes of the double[] object.
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shallowSizeOf
public static long shallowSizeOf(Object[] arr)
Returns the shallow size in bytes of the Object[] object.
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shallowSizeOf
public static long shallowSizeOf(Object obj)
Estimates a "shallow" memory usage of the given object. For arrays, this will be the memory taken by array storage (no subreferences will be followed). For objects, this will be the memory taken by the fields.JVM object alignments are also applied.
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shallowSizeOfInstance
public static long shallowSizeOfInstance(Class<?> clazz)
Returns the shallow instance size in bytes an instance of the given class would occupy. This works with all conventional classes and primitive types, but not with arrays (the size then depends on the number of elements and varies from object to object).- Throws:
IllegalArgumentException- ifclazzis an array class.- See Also:
shallowSizeOf(Object)
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adjustForField
public static long adjustForField(long sizeSoFar, Field f)This method returns the maximum representation size of an object.sizeSoFaris the object's size measured so far.fis the field being probed.The returned offset will be the maximum of whatever was measured so far and
ffield's offset and representation size (unaligned).
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humanReadableUnits
public static String humanReadableUnits(long bytes)
Returnssizein human-readable units (GB, MB, KB or bytes).
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humanReadableUnits
public static String humanReadableUnits(long bytes, DecimalFormat df)
Returnssizein human-readable units (GB, MB, KB or bytes).
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sizeOf
public static long sizeOf(Accountable[] accountables)
Return the size of the provided array ofAccountables by summing up the shallow size of the array and thememory usagereported by eachAccountable.
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