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List:       openjdk-serviceability-dev
Subject:    Re: RFR: 8009204 : [dtrace] signatures returned by Java 7 jstack() are corrupted on Solaris
From:       "serguei.spitsyn () oracle ! com" <serguei ! spitsyn () oracle ! com>
Date:       2013-06-30 8:06:09
Message-ID: 51CFE6F1.5060608 () oracle ! com
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Hi Tomas,

The fix looks good.
Thank you for discovering, tracking down and fixing the issue!

Thanks,
Serguei

On 6/28/13 6:29 AM, Tomas Hurka wrote:
> Hi All,
> I would like to ask for review of JDK-8009204 \
> <http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=8009204> 
> Description of the problem:
> jstack() returns corrupted method signatures on Solaris. The issue can be easily \
> reproduce using the following DTrace script: 
> dtrace -x jstackstrsize=2048 -Z \
> 	-n 'hotspot_jni$target::: /0/{}' \
> 	-n 'syscall::write:entry /pid==$target/{jstack(1024)}' \
> 	-c 'java -version'
> 
> With Java 6, the output is roughly:
> 
> java/io/FileOutputStream.writeBytes([BII)V
> java/io/FileOutputStream.write([BII)V
> java/io/BufferedOutputStream.flushBuffer()V
> java/io/BufferedOutputStream.flush()V
> java/io/PrintStream.write([BII)V
> 
> With Java 7 and Java 8, the output is roughly:
> 
> java/io/FileOutputStream.riteBytes
> java/io/FileOutputStream.rite
> java/io/BufferedOutputStream.lushBuffer
> java/io/BufferedOutputStream.lush
> java/io/PrintStream.rite
> 
> Evaluation:
> The problem is caused by SymbolTable changes JDK-6990754. jhelper.d was never \
> updated with changes for CPSlot, so the low bit of the address of the Symbol is \
> set, which causes the off by 1-ness of the output. The klass name uses a untagged \
> constant pool entry, which is why it doesn't have the problem in the output. There \
> is a very similar bug JDK-7019165 reported against pstack output and the proposed \
> fix is basically backport of JDK-7019165 to jhelper.d. 
> Webrev:
> <http://cr.openjdk.java.net/~thurka/8009204/webrev.00/>
> 
> I tested the fix using above D-script on latest JDK 8 and JDK 7u sources.
> 
> Thanks,
> --
> Tomas Hurka   <mailto:tomas.hurka@oracle.com>
> NetBeans Profiler http://profiler.netbeans.org
> VisualVM http://visualvm.java.net
> Software Developer
> Oracle, Praha Czech Republic
> 


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