Re: [Wrapper-user] Debugging with wrapper

[Chandra P. <cp...@ig...>]

This is great. But there is slight problem with simply using -Xdebug
alone. There are two ways of debugging JVMs. JVMPI and JVMTI.
You can run VM with -Xdebug alone but it's not really interesting.
However, I think that's ok for the detecting JVMPI since JVMPI uses
-Xdebug option.

http://blogs.sun.com/roller/page/kto?entry=using_vm_agents

As far as I have tested, under JVMTI you can simply use -agentlib:jdwp 
option to debug. -Xdebug is not necessary.

For -Xdebug
http://java.sun.com/j2se/1.5.0/docs/guide/jvmti/jvmti.html

For JVMTI and JVMPI with debugging (JPDA)
http://java.sun.com/j2se/1.5.0/docs/guide/jpda/enhancements.html




Leif Mortenson wrote:
> Chandra, David,
>    I made some changes for the 3.2.1 release.
> 
>    The wrapper will now enter a "DebugJVM" mode if the 
> wrapper.java.command ends
> in "jdb" or "jdb.exe", or the "-Xdebug" argument is passed to the JVM.
> 
>    When operating in the "DebugJVM" mode, a warning will be displayed on 
> JVM launch
> if any of the timeouts are not set to 0.  The warning warns that the 
> ability to detect and
> restart a frozen JVM will be disabled.
> 
>    Then if a timeout does occur, it will be ignored.  But the first such 
> timeout will cause
> another warning to be displayed to the user stating which timeout was 
> encountered and
> saying that it may be caused by a debugger having suspended the JVM.
> 
>    Does this make everyone happy?
> 
> Cheers,
> Leif
> 
>  
> Chandra Patni wrote:
> 
>> I see how your proposal is more compliant and semantically correct 
>> than mine which is in the spirit of 'benevolent dictatorship'. Either 
>> way, it would be nice to have nice debugging experience.
>>
>>
>>
>> da...@sm... wrote:
>>
>>> I agree and disagree. I don't think the wrapper should set its ping 
>>> to  0 if debug is set, but I do think it should not restart when 
>>> debug is  set. Maybe record in in the log file that it timed out, but 
>>> due to  debug existing, the application won't be restarted, unless 
>>> there is  some super-sexy way of finding out from the debugged 
>>> application that  the wrapper thread (and others depending upon the 
>>> debugger that  connects to it) has been debug paused.
>>>
>>> My thoughts at least!
>>>
>>> Cheers again Leif!
>>>
>>> Quoting Chandra Patni <cp...@ig...>:
>>>
>>>> I think wrapper should set ping timeout to zero if -Xdebug and
>>>> -Xrunjdwp .... option is set  for JVMDI supporting VMs. And print out
>>>> this as warning. It should also do the same when -agentlib:jdwp...
>>>> option is set for newer JVMTI supporting VMs. Otherwise, it will always
>>>> result in surprised user.
>>>>
>>>>
>>>>
>>>> Leif Mortenson wrote:
>>>>
>>>>> Chandra,
>>>>> I'm not sure of any way to let the Wrapper know that the JVM is   
>>>>> paused due to
>>>>> debug mode.  You would not want to disable the ping timeout simply 
>>>>> because
>>>>> debug was enabled.    I should add a note about this or maybe 
>>>>> make   the Wrapper
>>>>> provide some additional info if the command line contains -Xdebug.  
>>>>> Setting
>>>>> wrapper.ping.timeout to 0 should solve the problem for you however.
>>>>>
>>>>> Cheers,
>>>>> Leif
>>>>>
>>>>> Chandra Patni wrote:
>>>>>
>>>>>> I started my JVM with
>>>>>> -Xdebug -Xnoagent -Djava.compiler=NONE   
>>>>>> -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=5005
>>>>>>
>>>>>> and attached IDE debugger. Blocked a JSP thread on a breakpoint.   
>>>>>> The wrapper restarts/shuts down (depending on   
>>>>>> wrapper.disable_restarts=TRUE) the VM.
>>>>>>
>>>>>>
>>>>>> ERROR  | wrapper  | 2006/05/09 16:35:02 | JVM appears hung: 
>>>>>> Timed   out waiting for signal from JVM.
>>>>>> ERROR  | wrapper  | 2006/05/09 16:35:02 | JVM did not exit on   
>>>>>> request, terminated
>>>>>> STATUS | wrapper  | 2006/05/09 16:35:03 | JVM Restarts disabled.   
>>>>>> Shutting down.
>>>>>> STATUS | wrapper  | 2006/05/09 16:35:03 | <-- Wrapper Stopped
>>>>>>
>>>>>> I can set the wrapper.ping.timeout to zero to avoid this.   
>>>>>> Shouldn't wrapper should detect debug mode?
>>>>>>
>>>>>>
>>>>>>
>>>>>> -------------------------------------------------------
>>>>>> Using Tomcat but need to do more? Need to support web services, 
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>>>>>
>>>>>
>>>>>
>>>>> -------------------------------------------------------
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>>>>> Get stuff done quickly with pre-integrated technology to make 
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>>>>> Download IBM WebSphere Application Server v.1.0.1 based on Apache 
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>>>>>
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>>>>
>>>>
>>>>
>>>> -------------------------------------------------------
>>>> Using Tomcat but need to do more? Need to support web services, 
>>>> security?
>>>> Get stuff done quickly with pre-integrated technology to make your 
>>>> job easier
>>>> Download IBM WebSphere Application Server v.1.0.1 based on Apache 
>>>> Geronimo
>>>> http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 
>>>>
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>>>
>>>
>>>
>>>
>>>
>>>
>>> -------------------------------------------------------
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>>> security?
>>> Get stuff done quickly with pre-integrated technology to make your 
>>> job easier
>>> Download IBM WebSphere Application Server v.1.0.1 based on Apache 
>>> Geronimo
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>>
>>
>>
>> -------------------------------------------------------
>> Using Tomcat but need to do more? Need to support web services, security?
>> Get stuff done quickly with pre-integrated technology to make your job 
>> easier
>> Download IBM WebSphere Application Server v.1.0.1 based on Apache 
>> Geronimo
>> http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642
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>>
> 
> 
> 
> -------------------------------------------------------
> Using Tomcat but need to do more? Need to support web services, security?
> Get stuff done quickly with pre-integrated technology to make your job 
> easier
> Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo
> http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642
> _______________________________________________
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