9.6.3 Class-wise statistical information output by the static field-based reference relationship output functionality

(1) Output format and output items

• Output format

  The output format of the class-wise statistical information output by the static field-based reference relationship output functionality is as follows:

  Reference of class option-specified-class-name from static field
  -------------------------------------------------------------#1
  static field static-field-declaring-class-name#2.static-field-name#2
  class-name(address)[area-name]
    class-name(address)[area-name]
      option-specified-class-name(address)[area-name]
  ------
  ...

  #1:

  The number of "-" (hyphens) that are output is equal to 37 added to the number of characters in option-specified-class-name.

  #2:

  Indicates the base of the reference relationship.

• Output items

  The following table describes the items shown in the output format.

  Table 9‒11: Output items (static field-based reference relationship output functionality)

  Output items	Meaning
  static-field-declaring-class-name	The class name declaring the static field that forms the base is output.
  static-field-name	The name of the static field that forms the base is output.
  class-name	The class name of the instance that references the instances of the classes specified in the -class option of the jheapprof command is output.
  address	The address of the instance is output.
  area-name	The area to which the instance belongs is output. Eden: Indicates the Eden area. Survivor: Indicates the Survivor area. Tenured: Indicates the Tenured area. EM(eid=<id>): Indicates the Explicit memory block.
  option-specified-class-name	The class name specified in the -class option of the jheapprof command is output.

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(2) Examples of output

This subsection gives an example output of the class-wise statistical information output by the static field-based reference relationship output functionality using the following source as an example:

import JP.co.Hitachi.soft.jvm.MemoryArea.*;
public class static_reference {
  public static void main(String args[]) {
    try {
      classA cls_a1 = new classA();
      classB cls_b1 = new classB();
      classB cls_b2 = new classB();
      classC cls_c1 = new classC();
      classC cls_c2 = new classC();
      classC cls_c3 = new classC();
      BasicExplicitMemory emem = new BasicExplicitMemory();
      classC cls_c4 = (classC)emem.newInstance(classC.class);
      cls_a1.s_cls_a = cls_a1;
      cls_a1.s_cls_b = cls_b1;
      cls_a1.s_cls_c = cls_c1;
      cls_a1.cls_b = cls_b2;
      cls_b1.cls_c = cls_c2;
      cls_b2.cls_c = cls_c3;
      cls_c1.cls_c = cls_c4;
      Thread.sleep(20000);
    } catch (Exception e) {e.printStackTrace();}
  }
}
class classA {
  static classA s_cls_a;
  static classB s_cls_b;
  static classC s_cls_c;
  classB cls_b;
}
class classB {
  classC cls_c;
}
class classC {
  classC cls_c;
  public classC(){
  }
}

The following figure shows the structure of the instances.

Figure 9‒8: Structure of the instances (static field-based reference relationship output functionality)

The following figure shows the output result of the static field-based reference relationship output functionality. In this case, the jheapprof command is executed specifying the argument -class class-name -staticroot.

Figure 9‒9: Output result (static field-based reference relationship output functionality)

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