VMware GemFire Java API Reference

ObjectSizer (Tanzu GemFire 10.1.4)

```
public interface ObjectSizer
```
The sizer interface defines a method that when called returns the size of the object passed in. Implementations may return hardcoded values for object size if the implementation knows the object size for all objects that are likely to be cached. You should use a sizer with a EvictionAttributes.createLRUHeapAttributes(ObjectSizer) or EvictionAttributes.createLRUMemoryAttributes(ObjectSizer) if you want to use a faster or more accurate method of sizing than provided by the default object sizer, which is SIZE_CLASS_ONCE

Since:

GemFire 3.0

Field Summary

Fields
Modifier and Type	Field	Description
`static ObjectSizer`	`DEFAULT`	The default object sizer, currently `SIZE_CLASS_ONCE`
`static ObjectSizer`	`REFLECTION_SIZE`	An implementation of `ObjectSizer` that calculates an accurate size for each object that it sizes.
`static ObjectSizer`	`SIZE_CLASS_ONCE`	An implementation of `ObjectSizer` that calculates an accurate size of the first instance of each class that is put in the cache.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type Method Description

int sizeof(java.lang.Object o)

- Field Detail
  - SIZE_CLASS_ONCE
```
@Immutable
static final ObjectSizer SIZE_CLASS_ONCE
```
    An implementation of ObjectSizer that calculates an accurate size of the first instance of each class that is put in the cache. After the first instance, it will return the same size for every instance of that class. This sizer is a compromise between generating accurate sizes for every object and performance. It should work well if the keys and values in the region don't vary greatly in size. For accurate sizing of every instance use REFLECTION_SIZE instead. This sizer does generate an accurate size for strings and byte arrays every time, because there is very little performance impact from sizing these objects.
    
    Since:
    
    GemFire 6.5
  - REFLECTION_SIZE
```
@Immutable
static final ObjectSizer REFLECTION_SIZE
```
    An implementation of ObjectSizer that calculates an accurate size for each object that it sizes. This sizer will add up the sizes of all objects that are reachable from the keys and values in your region by non-static fields. For objects that are all approximately the same size, consider using SIZE_CLASS_ONCE. It will have much better performance.
    
    Since:
    
    GemFire 6.5
  - DEFAULT
```
@Immutable
static final ObjectSizer DEFAULT
```
    The default object sizer, currently SIZE_CLASS_ONCE
    
    Since:
    
    GemFire 6.5
- Method Detail
  - sizeof
```
int sizeof(java.lang.Object o)
```