Data Sizer Java Utility Class

The attached Java class is an example utility that includes methods for determining in-memory size of individual domain objects, and entries in GemFire regions in serialized and deserialized form. It uses GemFire's own internal sizing facilities, and so it has a dependency on gemfire.jar. Please note that this is an example. It has not been thoroughly tested and it is not intended for production use.

Usage examples

Calculating the size of a pure domain object

The following code sample shows how to size and get an object histogram for an instance of Portfolio class:


    Object obj = new Portfolio();

    int objSize = SizeCalculator.sizeObject(obj);
    // Get object histogram
    String objHist = SizeCalculator.histObject(obj);


Printing the string objHist will produce output similar to the following:

clazz                               size    count  class CollectionHolder              96     4  class java.util.HashMap            128     2  class Portfolio                    152     1  class java.util.HashMap$Entry      288     6  class [Ljava.lang.String;          472     5  class Position                     608     4  class [Ljava.util.HashMap$Entry;   144     2  class java.lang.String            2976    62  class [B                          1208     1  class [C                          1760    62

Calculating the size of data in a GemFire region

Given a Gemfire region, the sizer can be invoked on it in a couple of ways, as shown in the following code snippet:

    Region dataRegion = ... // get a reference to the data region

    // Create an instance of SizeCalculator that prints to System.out

    SizeCalculator sizer = new SizeCalculator();

    // Iterate over all the objects in the region, size it, and

    // report the total and average size

    sizer.sizeRegion(dataRegion);

    // Iterate over 10 objects in the region, and report the total

    // and average size

    sizer.sizeRegion(dataRegion, 10);

The output from SizeCalculator.sizeRegion will look like so:

Total RegionEntry size (serialized): 28481408
Total RegionEntry size (deserialized): 61559808
Total Key size: 240000
Total Value size (serialized): 27206362
Total Value size (deserialized): 60519808
Average RegionEntry size (serialized): 2848
Average RegionEntry size (deserialized): 6155
Average Key size: 24
Average Value size (serialized): 2720
Average Value size (deserialized): 6051