Hotspot Debugger on Mac OS X Java 1.6 32-bit

[Derek Shinaberry]

All I know for certain about the source is that MacPorts pulls the  
source tarball from the link http://download.java.net/openjdk/jdk6/promoted/b16/openjdk-6-src-b16-24_apr_2009.tar.gz 
.  It looks like there is now a b17, but I have no idea whether it  
would build on a Mac or if it would work if it did build.  Maybe  
that's the source of my troubles.  I think maybe I'll give that a  
try.  I was afraid that maybe HSDB hadn't been ported.  Thanks for the  
info about the debug callable functions.  Those might go a long way  
towards understanding what's going on.  I tried to peek at some of the  
data structures, but quickly descended into casting and pointer  
dereferencing hell.

On Feb 3, 2010, at 7:32 PM, Tom Rodriguez wrote:

> I assume the bits used by MacPorts are coming from http://hg.openjdk.java.net/bsd-port/bsd-port? 
>   That's the only working port of openjdk on the mac as far as I  
> know.  I know there are issues with 16 byte alignment in hotspot but  
> I assume all of them had been fixed in the bsd-port.  If this is  
> something they missed I'm sure they'd like to know.  You might try  
> their alias at http://mail.openjdk.java.net/mailman/listinfo/bsd-port-dev 
> .  As far as HSDB I don't believe it's been ported to bsd/mac.  It  
> needs either a core file reader, which would be different on the mac  
> since  I assume it's Mach-O, or an API for control a live process  
> like ptrace, and I don't think either has been written.  If you have  
> a debug build of hotspot there are functions that are callable from  
> the debugger which can be used to figure some things out, like  
> findpc which will try to indentify what a piece of generated code is  
> and ps which will dump a Java stack trace.  The full set is in src/ 
> share/vm/utilities/debug.cpp.
>
> tom
>
> On Feb 3, 2010, at 8:06 AM, Daniel D. Daugherty wrote:
>
>> Forwarding to hotspot-dev at ...
>>
>> Dan
>>
>>
>> Derek Shinaberry wrote:
>>> I am so far out of my depth here that I am not even sure which  
>>> mailing list to start with, but the serviceability-dev seemed as  
>>> good a place as any to begin.
>>>
>>> First of all, I am NOT well versed in Java, particularly the  
>>> minutia and all things VM related.  I am well versed in C++, which  
>>> led me to believe that I might have half a chance when it comes to  
>>> debugging a problem inside the VM.
>>>
>>> I'm running Mac OS X 10.5.8 on a 32-bit Core Duo processor, which  
>>> doesn't support Java 6.  So, I'm attempting to use OpenJDK 6  
>>> installed using MacPorts.
>>>
>>> After some issues getting the build to work, I figured out what  
>>> needed patching and succeeded in building and installing  
>>> openjdk6.  So far, so good.
>>>
>>> The program I'm running that required Java 6, called Marketcetera,  
>>> crashes fairly frequently.  Using gdb to investigate the crash, I  
>>> figured out that it has to do with 16-byte stack alignment  
>>> requirements on Mac OS X.  I discovered a patch by Landon Fuller  
>>> that attempts to address the issues.  I fought for a while to get  
>>> that patch integrated and building, but it finally built and  
>>> installed.  Still having the same crash and it is still related to  
>>> stack alignment.
>>>
>>> I've tracked it down to code that is being generated at runtime,  
>>> so gdb isn't much use in discovering exactly what code is the  
>>> source of the problem.  Enter the Hotspot Debugger. (Finally, he  
>>> gets to the point!)
>>>
>>> It doesn't appear that HSDB is built by MacPorts on Mac OS X.  It  
>>> doesn't even look like there is a bsd directory which would  
>>> presumably contain that code.  Has anyone successfully used HSDB  
>>> on Mac OS X?  Can anyone point me in the right direction for being  
>>> able to understand what is going on inside the VM on Mac OS X?   
>>> Any help would be much appreciated.
>>>
>>> Cheers,
>>> Derek
>
>