open jdk debug options
Jon Masamitsu
Jon.Masamitsu at Sun.COM
Tue Oct 7 22:05:55 PDT 2008
When you start
dbx java
you are starting dbx on the java launcher. The
launcher does an exec of the VM.
In the output below from dbx the "stopped in main"
indicates that the exec has happened and you've
stopped in the main of the VM. At that point
dbx has forgotten about the breakpoints you've
set because it thinks the breakpoints are in the
launcher.
You need to set your LD_LIBRARY_PATH
to point to the libjvm.so that you've built.
Compile this program
public class PrintLibraryPath {
public static void main(String[] args) {
System.out.println(System.getProperty("java.library.path"));
}
}
and execute it with the java you want to debug.
I have /usr/jdk/jdk1.5.0_11/bin/java so
-------------------
/usr/jdk/jdk1.5.0_11/bin/java PrintLibraryPath
/usr/jdk/instances/jdk1.5.0/jre/lib/sparc/server:/usr/jdk/instances/jdk1.5.0/jre/lib/sparc:/usr/jdk/instances/jdk1.5.0/jre/../lib/sparc:/usr/lib
-------------------
prints the LD_LIBRARY_PATH for /usr/jdk/jdk1.5.0_11/bin/java
Set your LD_LIBRARY_PATH accordingly.
Then start dbx on java and you should see something like
-------------------
dbx /usr/jdk/jdk1.5.0_11/bin/java
For information about new features see `help changes'
To remove this message, put `dbxenv suppress_startup_message 7.5' in
your .dbxrcReading java
Reading ld.so.1
Reading libthread.so.1
Reading libdl.so.1
Reading libc.so.1
-------------------
Run with -version
-------------------
dbx: run -version
Running: java -version
(process id 6309)
Reading libc_psr.so.1
Reading libjvm.so
Reading libsocket.so.1
Reading libsched.so.1
Reading libCrun.so.1
Reading libm.so.1
Reading libnsl.so.1
Reading libm.so.2
Reading libscf.so.1
Reading libdoor.so.1
Reading libuutil.so.1
Reading libmd5.so.1
Reading libmd5_psr.so.1
Reading libmp.so.2
Reading libhpi.so
Reading libverify.so
Reading libjava.so
Reading libzip.so
java version "1.5.0_11"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_11-b03)
Java HotSpot(TM) Server VM (build 1.5.0_11-b03, mixed mode)
execution completed, exit code is 0
dbx:
-------------------
Running with -version causes the VM to execute and all the
libraries get loaded. You should them see your
/scratch/wang/java_tm_7/lib/sparc/server/libjvm.so
You should be able to set your breakpoints now and run
with your real java command line.
Cong Wang wrote:
> Hi Jon:
> I went into the ALT_OUTPUTDIR/bin
> start dbx with :
> dbx java
> For information about new features see `help changes'
> To remove this message, put `dbxenv suppress_startup_message 7.6' in your .dbxrc
> Reading java
> Reading /usr/lib/ld.so.1
> Reading /lib/libthread.so.1
> Reading /scratch/wang/java_tm_7/lib/sparc/jli/libjli.so
> Reading /lib/libdl.so.1
> Reading /lib/libc.so.1
>
> then I map the src file foler into the current folder, using pathmap
>
> pathmap /scratch/wang/openjdk/hotspot/src/cpu/sparc/vm
> /scratch/wang/java_tm_7/bin
>
> after the pathmap, I try to find the function using
>
> whereis compiler_lock_object
>
> there is no output.
>
> But I know that function is in
> /scratch/wang/java_tm_7/lib/sparc/server/libjvm.so, therefore
> I use the following to load the shared library:
> loadobject -load /scratch/wang/java_tm_7/lib/sparc/server/libjvm.so
> Reading /scratch/wang/java_tm_7/lib/sparc/server/libjvm.so
> Loaded loadobject: /scratch/wang/java_tm_7/lib/sparc/server/libjvm.so
>
> now, when I use whereis to find compiler_lock_object, I got:
> whereis compiler_lock_object
> function:
> `/scratch/wang/java_tm_7/lib/sparc/server/libjvm.so`assembler_sparc.cpp`#__1cOMacroAssemblerUcompiler_lock_object6MpnMRegisterImpl_222pnVBiasedLockingCounters__v_
> [non -g, demangles to:
> MacroAssembler::compiler_lock_object(RegisterImpl*,RegisterImpl*,RegisterImpl*,RegisterImpl*,BiasedLockingCounters*)]
>
> Then, I set a break point using:
> stop in compiler_lock_object
> dbx: warning: 'compiler_lock_object' has no debugger info -- will
> trigger on first instruction
> (2) stop in MacroAssembler::compiler_lock_object(RegisterImpl*,RegisterImpl*,RegisterImpl*,RegisterImpl*,BiasedLockingCounters*)
>
>
> So, I run my application in the debugger
> using:
>
> run -server -Xcomp -Xbatch -Xss128k -XX:NewSize=256m -Xnoclassgc
> -verbose:gc -classpath /scratch/wang/java_tm_7/bin/
> SynchronizedCounter
>
> (process id 25142)
> dbx: process 25142 about to exec("/scratch/wang/java_tm_7/bin/java")
> dbx: program "/scratch/wang/java_tm_7/bin/java" just exec'ed
> dbx: to go back to the original program use "debug $oprog"
> t at 1 (l at 1) stopped in main at 0x00010d30
> 0x00010d30: main : save %sp, -128, %sp
>
> (dbx) cont
> t at 2 (l at 2) signal SEGV (no mapping at the fault address) in (unknown)
> at 0xfc063710
> 0xfc063710: ld [%o0 + 4], %l0
> Current function is jni_invoke_nonstatic (optimized)
> 1084 JavaCalls::call(result, method, &java_args, CHECK);
>
> I will never get to my break point. But if I run this outside dbx,
> everything works fine.
>
> SynchronizedCounter is a small multi-threaed java program I wrote to
> test the jvm. It has two threads try to grab a lock and increment a
> shared counter.
> It works fine but I want to change how the jvm manages the lock, so I
> want to stop the program when jvm creates a lock and acquires it.
>
> Thanks for any comment you may have in advance.
>
> Regards
> James Wang
>
>
> On Tue, Oct 7, 2008 at 10:03 PM, Jon Masamitsu <Jon.Masamitsu at sun.com> wrote:
>
>> How do you start dbx on java? And what is dbx saying
>> exactly?
>>
>> Cong Wang wrote:
>>
>>> Hi all:
>>> I am trying to modify some part of the hotspot runtime interpreter
>>> and I would like to debug that using either dbx or gdb. I have compile
>>> the file using the following options:
>>>
>>> ALT_BINARY_PLUGS_PATH=/scratch/wang/openjdk-binary-plugs
>>> ALT_FREETYPE_LIB_PATH=/usr/local/lib
>>> ALT_FREETYPE_HEADERS_PATH=/usr/local/include
>>> ALT_CUPS_HEADERS_PATH=/scratch/wang/cups-1.3.8
>>> ANT_HOME=/usr/sfw
>>> ALT_OUTPUTDIR=/scratch/wang/java_tm_7
>>> DEV_ONLY=true
>>> DEBUG=true
>>>
>>> I am not able to use dbx to debug java in the ALT_OUTPUTDIR/bin
>>> directory. I would like to set a break point at
>>> hotspot/src/cpu/sparc/vm/assembler_sparc.cpp
>>> MacroAssembler::compiler_lock_object function. I have tried to use the
>>> dbx pathmap command but it doesn't seem to help dbx to locate the
>>> source file or the function definition.
>>> Any suggestions? Thanks in advance for any comment.
>>>
>>>
>>>
>>
>
>
>
>
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