Comment 1 Andrew Johnson 2011-02-17 07:30:11 EST

It looks like no class called java.lang.Class has been found in the dump. Is the dump corrupted?

Comment 2 Andrew Johnson 2011-03-03 04:30:00 EST

Does the jhat tool supplied with Oracle/Sun SDKs read the dump successfully?

Was the heap dump transferred using ftp? Is it possible it was transferred in ASCII not binary?

Comment 3 Krum Tsvetkov 2011-05-23 05:32:33 EDT

I reduced the severity of this bug. We haven't heard anything new and haven't been able to reproduce.

Comment 4 wxie 2011-07-12 11:56:17 EDT

I got the exact same error. hprof is in binary format correct, and I opened the hprof file with jhat with the following message:

C:\Program Files\Java\jdk1.6.0_06\bin>jhat z:\temp\java_pid7036.hprof
Reading from z:\temp\java_pid7036.hprof...
Dump file created Fri Jul 08 12:06:53 EDT 2011
Snapshot read, resolving...
Resolving 0 objects...
WARNING:  hprof file does not include java.lang.Class!
WARNING:  hprof file does not include java.lang.String!
WARNING:  hprof file does not include java.lang.ClassLoader!
Chasing references, expect 0 dots
Eliminating duplicate references
Snapshot resolved.
Started HTTP server on port 7000

When I click the "Show finalizer summary" link in jhat, I got the following error. thanks.

Exception in thread "Thread-53" java.lang.NullPointerException
        at com.sun.tools.hat.internal.model.Snapshot.getFinalizerObjects(Snapshot.java:393)
        at com.sun.tools.hat.internal.server.FinalizerSummaryQuery.run(FinalizerSummaryQuery.java:26)
        at com.sun.tools.hat.internal.server.HttpReader.run(HttpReader.java:181)
        at java.lang.Thread.run(Thread.java:619)

Comment 5 tmccord 2011-09-20 12:18:14 EDT

I have observed this with heap dumps taken from JDK 1.5.0_11+ JDKs on Red Hat.  Jmap was used to generate the heap dump.  However, histogram listing from jmap does show java.lang.Class: 
 
Size    Count   Class description
-------------------------------------------------------
117016288       1112362 char[]
54692528        502140  java.lang.Object[]
52775520        365553  * ConstMethodKlass
...
9778688 152792  java.util.HashMap
9408320 58802   org.apache.jetspeed.om.folder.proxy.FolderProxy
8638920 56835   java.lang.reflect.Method
8135808 84748   org.apache.jetspeed.om.page.proxy.PageProxy
6608736 11798   * MethodDataKlass
5615280 31905   java.lang.Class

Comment 6 Andrew Johnson 2012-02-21 13:06:12 EST

Failure is at:
        ClassImpl javaLangClass = javaLangClasses.get(0);
Perhaps we could need to create dummy classes for java.lang.Class and java.lang.Classloader if they do not exist due to a corrupt dump.
The DTFJ parser does something similar.

Comment 7 WJ Gerritsen 2016-02-02 06:53:11 EST

Created attachment 259486 [details]
Dump that generates a NullPointerException while parsing

I do have this same issue while reading the attached dump. The error log contains:

!SESSION 2016-02-02 12:47:15.943 -----------------------------------------------
eclipse.buildId=unknown
java.version=1.8.0_66
java.vendor=Oracle Corporation
BootLoader constants: OS=win32, ARCH=x86_64, WS=win32, NL=en_US
Command-line arguments:  -os win32 -ws win32 -arch x86_64

!ENTRY org.eclipse.mat.ui 1 0 2016-02-02 12:47:53.775
!MESSAGE Detected compressed references, because with uncompressed 64-bit references the array at 0xfab008c8 would overlap the array at 0xfab00378

!ENTRY org.eclipse.mat.ui 1 0 2016-02-02 12:47:53.969
!MESSAGE Heap C:\temp\mon.bin contains 123,987 objects

!ENTRY org.eclipse.core.jobs 4 2 2016-02-02 12:47:54.063
!MESSAGE An internal error occurred during: "Parsing heap dump from 'C:\temp\mon.bin'".
!STACK 0
java.lang.NullPointerException
	at org.eclipse.mat.hprof.HprofParserHandlerImpl.resolveClassHierarchy(HprofParserHandlerImpl.java:587)
	at org.eclipse.mat.hprof.Pass2Parser.readInstanceDump(Pass2Parser.java:205)
	at org.eclipse.mat.hprof.Pass2Parser.readDumpSegments(Pass2Parser.java:159)
	at org.eclipse.mat.hprof.Pass2Parser.read(Pass2Parser.java:89)
	at org.eclipse.mat.hprof.HprofIndexBuilder.fill(HprofIndexBuilder.java:94)
	at org.eclipse.mat.parser.internal.SnapshotFactoryImpl.parse(SnapshotFactoryImpl.java:222)
	at org.eclipse.mat.parser.internal.SnapshotFactoryImpl.openSnapshot(SnapshotFactoryImpl.java:126)
	at org.eclipse.mat.snapshot.SnapshotFactory.openSnapshot(SnapshotFactory.java:145)
	at org.eclipse.mat.ui.snapshot.ParseHeapDumpJob.run(ParseHeapDumpJob.java:83)
	at org.eclipse.core.internal.jobs.Worker.run(Worker.java:55)

And indeed with jhat I can navigate the heap dump

Comment 8 Sourabh Kumar 2016-07-14 02:26:10 EDT

I am also facing the same issue. Can you please let me know how to add the patch provided in eclipse.

Comment 9 Sourabh Kumar 2016-07-14 02:27:07 EDT

I am also facing the same issue. Can you please let me know how to add the patch provided in eclipse.

Comment 10 Andrew Johnson 2016-11-24 08:03:40 EST

The fix for bug 471757 allows me to open the dump attached to this bug.

*** This bug has been marked as a duplicate of bug 471757 ***