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From "Xiao-Feng Li (JIRA)" <j...@apache.org>
Subject [jira] Updated: (HARMONY-4114) [drlvm][test] Fragmentation related tests report failure for lower heap utilization rate than RI
Date Mon, 18 Jun 2007 06:22:26 GMT

     [ https://issues.apache.org/jira/browse/HARMONY-4114?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Xiao-Feng Li updated HARMONY-4114:
----------------------------------

    Assignee:     (was: Xiao-Feng Li)
     Summary: [drlvm][test] Fragmentation related tests report failure for lower heap utilization
rate than RI  (was: [drlvm][gc] GC cannot work with fragmented heap with small heap size)

Need to study the test case design. The execution itself is correct by throwing an OOME exception.
Just the heap utilization rate is lower than RI, which is not a correctness issue of GC.

> [drlvm][test] Fragmentation related tests report failure for lower heap utilization rate
than RI
> ------------------------------------------------------------------------------------------------
>
>                 Key: HARMONY-4114
>                 URL: https://issues.apache.org/jira/browse/HARMONY-4114
>             Project: Harmony
>          Issue Type: Bug
>          Components: DRLVM
>         Environment: Windows
>            Reporter: Vera Petrashkova
>            Priority: Minor
>         Attachments: patch-for-H4114-001.patch
>
>
> VM intermittently throws unexpected OutOfMemoryError on the following test which defines
heap fragmentation.
> This test allocates bytes arrays of different sizes. 
> The arrays sizes are up to the defined MAX memory, but it is always checked that the
total arrays size does not reach this MAX value.
> Some of the arrays are deleted (assigned to null) with the step which varies from 2 to
13, so, fragmentation of heap becomes high. 
> Test fails on DRLVM  with -Xmx64M and sometimes VM crashes on this test without of throwing
OutOfMemoryError.
> On RI this test always passes with -Xmx64Mю
> -------------fragTest.java------------
> public class fragTest {
>     public final static int NUM_IT = 1000000; 
>     public final static int MAX_MEM =  44000000;
>     public final static int BSIZE = 65536;
>     public final static int MIN_BSIZE = 1;
>     public final static int PERIOD = 25000;
>     static int count=0;
>     static int totalSize = 0;
>     public static byte [][] ref = new byte [NUM_IT][];
>     public static void main(String[] args) {
>         int i = 0;
>         try {
>             for (; i < NUM_IT; ++i) {
>                 // size varies from MIN_BSIZE to (BSIZE + MIN_BSIZE)
>                 int size = ((i + BSIZE) % BSIZE) + MIN_BSIZE;
>                 while (totalSize + size > MAX_MEM) {
>                     size = size / 2;
>                     if (size < MIN_BSIZE)
>                         break;
>                 }
>                 if (size >= MIN_BSIZE) {
>                     ref[i] = new byte[size];
>                     totalSize += 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 = (i % 13) + 2;
>                     for(int j = 0; j<i; j+=step) {
>                        if ( ref[j]!= null) {
>                            totalSize-=ref[j].length; //recalculate total size
>                            ref[j]= null;//clear array
>                        }
>                     }
>                     count = 0;
> //                    System.err.println("Total size = " + totalSize);
>                 }
>             }
>             System.err.println("Test passed, Total size = " + totalSize);
>         } catch (OutOfMemoryError e) {
>             System.err.println("OutOfMemoryError is thrown. Total size = "
>                     + totalSize + " i = " + i);
>             System.err.println("Test failed");
>         }
>     }
> }
> -----------------
> Run this test several times.
> java -Xmx64M fragTest
> On RI output always is the following:
> ===============
> 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 = 44000000
> DRLVM output:
> =============
> Apache Harmony Launcher : (c) Copyright 1991, 2006 The Apache Software Foundation or
its licensors, as applicable.
> java version "1.5.0"
> pre-alpha : not complete or compatible
> svn = 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 = 39269205 i = 50083
> Test failed
> Apache Harmony Launcher : (c) Copyright 1991, 2006 The Apache Software Foundation or
its licensors, as applicable.
> java version "1.5.0"
> pre-alpha : not complete or compatible
> svn = 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 test suite (http://issues.apache.org/jira/browse/HARMONY-3536)

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