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  1. JDK
  2. JDK-7033738

Hotspot class loading requires 50% more memory than CVM

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    Details

    • Type: Enhancement
    • Status: Resolved
    • Priority: P3
    • Resolution: Fixed
    • Affects Version/s: 6u21
    • Fix Version/s: None
    • Component/s: embedded
    • Labels:
    • CPU:
      generic
    • OS:
      generic

      Description

      Running this program on Hotspot/SE-E compared to CDC shows that CDC can load Java classes in 50% less memory. This RFE is used to track the invesigation into why this is occuring. I modified the Hotspot VM to not parse and load the Line Number Information but this only saved 1M out of the total 74M on Linux/x86 systems.

      Here's the RSS that I saw when running this test program on the entire rt.jar class list.

      CVM/CDC6 43152K
      Hotspot 74456k



      import java.lang.*;
      import java.io.*;
      import java.util.*;

      public class LoadClassesFromList {
          static String loadFileName;

          public static void main(String[] args) {
      loadFileName = args[0];
      loadClassesFromFileList();

      System.out.println("Doing GC Before Exit\n");
      System.gc();

      System.out.println("waiting for exit: ");
      try {
      Thread.sleep(30000L);
      } catch (Throwable e) {
      e.printStackTrace();
      }
          }
          
          public static void loadClassesFromFileList()
          {
      String str;
      try {
      BufferedReader in =
      new BufferedReader(new FileReader(loadFileName));
      while ((str = in.readLine()) != null) {
      try {
      Class clz = Class.forName(str, false, null);
      //System.out.println("class loaded: " + clz);
      } catch (Throwable ee) {
      System.out.println(ee.toString());
      }
      }
      in.close();

      } catch (Exception ee) {
      ee.printStackTrace();
      }
          }
      }

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            • Assignee:
              jiangli Jiangli Zhou
              Reporter:
              bobv Bob Vandette
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              Dates

              • Created:
                Updated:
                Resolved:
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