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Date: Thu, 14 Jun 2007 20:39:26 -0700 (PDT)
From: "Qi Ji (JIRA)" <jira@apache.org>
To: commits@harmony.apache.org
Subject: [jira] Updated: (HARMONY-4114) [drlvm][gc] GC cannot work with
 fragmented heap with small heap size
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     [ https://issues.apache.org/jira/browse/HARMONY-4114?page=3Dcom.atlass=
ian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Qi Ji updated HARMONY-4114:
---------------------------

    Attachment: patch-for-H4114-001.patch

This patch fix H4114 bug.

> [drlvm][gc] GC cannot work with fragmented heap with small heap size
> --------------------------------------------------------------------
>
>                 Key: HARMONY-4114
>                 URL: https://issues.apache.org/jira/browse/HARMONY-4114
>             Project: Harmony
>          Issue Type: Bug
>          Components: DRLVM
>         Environment: Windows
>            Reporter: Vera Petrashkova
>            Assignee: Xiao-Feng Li
>            Priority: Minor
>         Attachments: patch-for-H4114-001.patch
>
>
> VM intermittently throws unexpected OutOfMemoryError on the following tes=
t which defines heap fragmentation.
> This test allocates bytes arrays of different sizes.=20
> The arrays sizes are up to the defined MAX memory, but it is always check=
ed that the total arrays size does not reach this MAX value.
> Some of the arrays are deleted (assigned to null) with the step which var=
ies from 2 to 13, so, fragmentation of heap becomes high.=20
> Test fails on DRLVM  with -Xmx64M and sometimes VM crashes on this test w=
ithout of throwing OutOfMemoryError.
> On RI this test always passes with -Xmx64M=D1=8E
> -------------fragTest.java------------
> public class fragTest {
>     public final static int NUM_IT =3D 1000000;=20
>     public final static int MAX_MEM =3D  44000000;
>     public final static int BSIZE =3D 65536;
>     public final static int MIN_BSIZE =3D 1;
>     public final static int PERIOD =3D 25000;
>     static int count=3D0;
>     static int totalSize =3D 0;
>     public static byte [][] ref =3D new byte [NUM_IT][];
>     public static void main(String[] args) {
>         int i =3D 0;
>         try {
>             for (; i < NUM_IT; ++i) {
>                 // size varies from MIN_BSIZE to (BSIZE + MIN_BSIZE)
>                 int size =3D ((i + BSIZE) % BSIZE) + MIN_BSIZE;
>                 while (totalSize + size > MAX_MEM) {
>                     size =3D size / 2;
>                     if (size < MIN_BSIZE)
>                         break;
>                 }
>                 if (size >=3D MIN_BSIZE) {
>                     ref[i] =3D new byte[size];
>                     totalSize +=3D size;
>                 }
>                 count++;
>                 // clearing of arrays on PERIOD step
>                 if (count > PERIOD) {
>                     // clearing of arrays is perfromed with the step,
>                     // which varies from 2 to 13, so, the heap becomes
>                     // fragmented
>                     int step =3D (i % 13) + 2;
>                     for(int j =3D 0; j<i; j+=3Dstep) {
>                        if ( ref[j]!=3D null) {
>                            totalSize-=3Dref[j].length; //recalculate tota=
l size
>                            ref[j]=3D null;//clear array
>                        }
>                     }
>                     count =3D 0;
> //                    System.err.println("Total size =3D " + totalSize);
>                 }
>             }
>             System.err.println("Test passed, Total size =3D " + totalSize=
);
>         } catch (OutOfMemoryError e) {
>             System.err.println("OutOfMemoryError is thrown. Total size =
=3D "
>                     + totalSize + " i =3D " + i);
>             System.err.println("Test failed");
>         }
>     }
> }
> -----------------
> Run this test several times.
> java -Xmx64M fragTest
> On RI output always is the following:
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> java version "1.5.0_06"
> Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_06-b05)
> Java HotSpot(TM) Client VM (build 1.5.0_06-b05, mixed mode)
> Test passed, Total size =3D 44000000
> DRLVM output:
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> Apache Harmony Launcher : (c) Copyright 1991, 2006 The Apache Software Fo=
undation or its licensors, as applicable.
> java version "1.5.0"
> pre-alpha : not complete or compatible
> svn =3D r545076, (Jun  7 2007), Windows/ia32/msvc 1310, release build
> http://harmony.apache.org
> The GC did not provide gc_add_weak_root_set_entry()
> OutOfMemoryError is thrown. Total size =3D 39269205 i =3D 50083
> Test failed
> Apache Harmony Launcher : (c) Copyright 1991, 2006 The Apache Software Fo=
undation or its licensors, as applicable.
> java version "1.5.0"
> pre-alpha : not complete or compatible
> svn =3D r545076, (Jun  7 2007), Windows/ia32/msvc 1310, release build
> http://harmony.apache.org
> The GC did not provide gc_add_weak_root_set_entry()
> Out of Memory!
> This bug causes the itermittent failures of  gc.frag tests from stress te=
st suite (http://issues.apache.org/jira/browse/HARMONY-3536)

--=20
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