attach to process not started in debug mode?

[Les Caudle]

Is there a way to attach to a process of a .NET app not started in debug mode?

I'm having a problem with an app on a remote server, with a 3rd party .net
object I dont' have source files for anyway.

I'd like to be able to just attach to the hung process and get some debug info.

Is this possible?

 

[Peter Duniho]

[...]
I'd like to be able to just attach to the hung process and get some
debug info.

Is this possible?

Yes.

 

[Jeffrey Tan[MSFT]]

Hi Les,

Based on my understanding, I assume your "debug mode" means the application
debug build. That is your application components is built in release
configuration.

Yes, you can use any debugger to attach a release build application as long
as you have enough priviledge/permissions on remote machine. Debugger will
use .Net/Win32 debugging service to attach the process, so it does not
matter if the target is debug or release build.

Normally, release build is not special comparing to debug build. It will
just perform optimize for the generated code. For example, if there is any
local variables can be eliminated, the release build will discard them in
generated assemblies. Below link talks about the C/C++ code difference
between debug and release build, however, the idea is the same for .Net
compiler:
"Debug versus Release build"
http://www.dotnetheaven.com/Uploadfile/mahesh/DebugaRelease05192005033225AM/
DebugaRelease.aspx

Finally, to debug 3rd party assembly, if the assembly is not obfruscated, I
would recommend you to download Reflector from the link below and use the
Reflector to examine the source code of it. Due to the strong metadata in
the .Net assembly, it is possible for Reflector tool to decompile the
assembly code for review.(A extreme example is .Net Framework assemblies,
which can be decompiled in Reflector for learning)
http://www.aisto.com/roeder/dotnet/

Hope this helps.

Best regards,
Jeffrey Tan
Microsoft Online Community Support
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[Jeffrey Tan[MSFT]]

Hi Les,

Have you reviewed my reply to you? Does it make sense to you? If you still
need any help or have any concern, please feel free to tell me, thanks.

Best regards,
Jeffrey Tan
Microsoft Online Community Support
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[Les Caudle]

Jeffrey - I've got a box at a remote ISP where I may need to debug the app from
time to time. I can debug my code, but there is a 3rd party tool I'm using, and
this problem only seems to happen in the field when a method of that tools is
called.

I installed Visual Studio Express, but there doesn't seem to be any ability to
'attach to process'.

I should have put the full Visual Studio on it before I took it out there.

So, with the tools I can easily install remotely, is there a way to attach to
the process of the C# app, and be able to debug it in some useful manner (esp
attach to a hung thread)?

Thanks, Les Caudle

 

[Jeffrey Tan[MSFT]]

Hi Les,

Thank you for the feedback.

Sorry, but I do not think I understand your question completely. Is your
problem caused by VS Express version or 3rd party libraries? If it is
caused by 3rd party code, can you be specific about what problem is caused
by 3rd party code during debugging? Thanks.

Yes, Visual Studio Express debugger does not support the "Attach to
Process" function. You need "Standard Edition" above to get the dynamic
attaching function:
"How to: Attach to a Running Process "
http://msdn2.microsoft.com/en-us/library/c6wf8e4z.aspx

Do you want to perform remote debugging with your application/process
running on remote machine? That is you do not want to install the VS
debugger on remote machine. Does this problem has anything to do with your
original "debug mode" question? If you want to know how to perform remote
debugging with VS2005, please refer to the official tutorials below:
http://support.microsoft.com/kb/910448
http://blogs.msdn.com/yosit/archive/2003/06/20/9024.aspx
http://msdn2.microsoft.com/en-us/library/bt727f1t(VS.80).aspx

Finally, I have written a blog entry regarding how to debug crash/hang in a
production environment with windbg/Process Explorer, it may make sense to
you:
"How to debug application crash/hang in production environment?"
http://blogs.msdn.com/msdnts/archive/2006/11/24/how-to-debug-application-cra
sh-hang-in-production-environment.aspx

If I have misunderstood your concern, please feel free to let me know, I
will work with you, thanks.

Best regards,
Jeffrey Tan
Microsoft Online Community Support
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[Les Caudle]

Jeffrey - I ran into a problem where a 3rd party .NET dll would hang on a method
call, but only on my production server.

I wanted to be able to debug this, and tell the 3rd party tool supplier where
his code was hanging.

I thought I might be able to debug if I installed VS Express on the box, and
that is what I'm trying to figure out - the best way to debug something like
this.

The 3rd party tool supplier has already found the problem, but I'm interested in
a solutioni in case this comes up again.

Thanks, Les Caudle

 

[Jeffrey Tan[MSFT]]

Hi Les,

Thank you for providing the background infomation!

Yes, you may install the VS Express on the production server and use the VS
debugger to launch the application waiting for the hang. When the hang
appears in the debuggee, you may press Ctrl+Break in VS Express debugger to
stop the hang application. In the Call Stack window, you may get the hang
call stack of your application(remember to switch to the hang thread in the
Threads window). Note: to get the full stack trace of the hang, you may
need to disable the "Just My Code" feature of VS2005 debugger(the default
setting is on). Please refer to the link below for details:
"How to: Step Into Just My Code"
http://msdn2.microsoft.com/en-us/library/h5e30exc.aspx
"Is 'Just my Code' for you?"
http://blogs.msdn.com/greggm/archive/2004/07/29/201315.aspx

Actually, due to the big footprint of Visual Studio, it would be better to
use windbg or Process Explorer to troubleshoot the hang problem. My blog
entry below demonstrated the detailed steps:
"How to debug application crash/hang in production environment?"
http://blogs.msdn.com/msdnts/archive/2006/11/24/how-to-debug-application-cra
sh-hang-in-production-environment.aspx

Hope this helps.

Best regards,
Jeffrey Tan
Microsoft Online Community Support
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[Les Caudle]

Jeffrey - do I need to have the full source code on the production box, and
start the program as I would on my development box - or can I somehow debug just
the program (compiled in debug mode)?

Thanks, Les Caudle

 

[Jeffrey Tan[MSFT]]

Hi Les,

Thank you for the feedback.

This depends on your requirement. There are 2 types of debugging: source
code level and binary level(without source code). So, do you have the
source code for the 3rd party product?

If you have source code for it, you also have to obtain the private symbol
file from the 3rd party vendor. The debugger has no knowledge to determine
if a set of source files are associated with which assembly, so it must
first load the private symbol file for the symbol. The private symbol file
internally contains the source code path in it. So, you should set the
symbol path to the private symbol file in Tools ->Options ->Debugging
->Symbols. Note: this debugging has nothing to do with debug or release
mode. As I stated in the original post, the debug mode only does few/no
optimize with the generated assembly. It has nothing to do with debugging.

It is always good to have source code for debugging. However, since the
assembly is a 3rd party product, you may not have source code for it. That
is the reason of using binary level debugging.(Another example is debugging
..Net Framework BCL, whose source code is also not available) Even you do
not have source code, you may just perform binary level debugging with it,
since the .Net assembly metadata can self-describe its code/data. So you
can still get the full stack trace of this hang. The stack method will be
displayed in call stack window by querying the metadata.

I am not sure if my explanation has resolved your confusion. If I have
misunderstood your key concern, please feel free to tell me and explain
your concern in details. Thanks.

Best regards,
Jeffrey Tan
Microsoft Online Community Support
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[Les Caudle]

Jeffrey - I do not have the source to the 3rd party tool used in my .NET app.

Without source to this, and without loading all my source code scattered in
different directories on drive letters that don't exist on the production
server, what are the steps to try to debug my code if it hangs calling a method
of the 3rd party tool?

Is there a way to attach to a process in VS Express, without having the source
code, just an exe and dll's?

Thanks, Les Caudle

 

[Jeffrey Tan[MSFT]]

Hi Les,

Thanks for your feedback.

As I already confirmed in the original reply, VS express debugger does not
support the "Attach to Process" function, this has nothing to do with
whether we have source code or not. You need "Standard Edition" above
installing on your production server to attach to your running Exe.

Alternately, you may download the free debugger windbg from Microsoft site
to perform the debugging without installing Visual Studio Standard Edition.
I have completely written down the detailed steps in the blog entry below,
have you read it?
"How to debug application crash/hang in production environment?"
http://blogs.msdn.com/msdnts/archive/2006/11/24/how-to-debug-application-cra
sh-hang-in-production-environment.aspx

Debugging hang is somewhat easy, since (normally) the call stack will
reveal the root cause of the hang position. Also, .Net metadata allows the
debugger to display the call stack without getting the symbol files.

Is this clear for you? If there is still any concept unclear, please feel
free to point it out. Thanks.

Best regards,
Jeffrey Tan
Microsoft Online Community Support
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[Jeffrey Tan[MSFT]]

Hi Les,

Have you reviewed my reply to you? Does it make sense to you? Is your
problem resolved? If you still need any help or have any concern, please
feel free to feedback, thanks.

Best regards,
Jeffrey Tan
Microsoft Online Community Support
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[Les Caudle]

Jeffrey - thanks for you detailed info.

I didn't end up having to debug the 3rd party tool, they fixed their problem,
but with your info I'll be able to do that if another problem arises.

Thanks, Les Caudle

 

[Jeffrey Tan[MSFT]]

Hi Les,

Thank you for confirming the status.

Ok, if you need further help, please feel free to post, thanks.

Best regards,
Jeffrey Tan
Microsoft Online Community Support
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