9.4.2 Class-wise statistical information output by the instance statistical functionality

(1) Output format and output items

The output format of the class-wise statistical information output by the instance statistical functionality is as follows:

• Output format

  Java Heap Profile
  -----------------------
  ________________Size__Instances__Class________________
   <total_size> <Instance_count> <class_name>
   <total_size> <Instance_count> <class_name>
  ...

• Output items

  The items listed in the output format are described as follows.

  Table 9‒6: Output items (instance statistical functionality)

  Output items	Meaning
  <total_size>	The total size of the instance is output in byte unit.
  <Instance_count>	The number of instance is output.
  <class_name>	The class name is output.

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(2) Example of output

The output example of the class-wise statistical information output by the instance statistical functionality is described as the example of the following source.

public class instance {
 public static void main(String args[]) {
   classA cls_a = new classA();
   try {
     Thread.sleep(20000);
   } catch (Exception e) {}
 }
}
class classA {
 classB a1;
 classC a2;
 classA() {
   a1 = new classB();
   a2 = new classC();
 }
}
class classB {
 classD b1;
 String b2;
 classB() {
   b1 = new classD();
   b2 = null;
 }
}
class classC {
 String c1, c2;
 classC() {
   c1 = null;
   c2 = null;
 }
}
class classD {
 String d1, d2;
 classD() {
   d1 = null;
   d2 = null;
 }
}

The following figure shows the instance structure for above source.

Figure 9‒2: Instance structure (instance statistical functionality)

When using the above instance structure, add the following size for each class in the instance statistical functionality:

• Size of class A: a1+a2+ b1+b2+ c1+c2+ d1+d2

• Size of class B: b1+b2+ d1+d2

• Size of class C: c1+c2

• Size of class D: d1+d2

The following figure shows the output result of the instance statistical functionality.

Figure 9‒3: Output result (instance statistical functionality)

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