I'm trying to debug an issue that happens on service startup. Trying to attach while things are running is failing, windbg times out with an error about a link lock. I think that the error occurs before I have a chance to attach. A sleep might let me attach, but is there a more elegant solution?
I'd like to start up the debugger first thing as the service starts. C# has a Debugger.Launch() method to start a debugger at runtime. Is there an equivalent C call that can be used without .net? Something I could just drop in the start routine.
I can't call DebugBreak because at the time the service has started I'm not under a debugger.
Sleep is certainly a viable approach. It's crude yet effective. Somewhat less crude is to use a good logging framework to output diagnostics. With a sufficiently capable logging framework this can be very effective.
Related
I'm trying to debug for the first time a gtk code and actually, I want to debug a callback function for key-press-event so I set a breakpoint with gdb and when it hits the breakpoint, the whole desktop evirement is freezing (I'm running under gnome-shell) it seems that the graphic envirement is waiting for the event to finish.
I got some idea that didn't worked :
The first attempts was to assign some gdb commands to the breakpoint :
(gdb) break on_key_press_callback
(gdb) commands
> back trace
> next
> next
> next
> continue
> end
but I don't know why, only the back trace command is executed, and then freeze.
The second attempt was to debug remotely using gdbserver and gdb on tty1 (no graphigs to freeze :) ) I was able to send commands like next and step after the breakpoint but there was nothing to see (can't list code, inspect the stack, ect ...)
So any good tips to be able to debug in such situations ?
Thanks
It's typical to have lockups when debugging an X program running on the same server that you're using to debug. For example, if the inferior (gdb terminology for the program being debugged) does a server grab -- whoops, the gdb GUI (or terminal or emacs etc) is locked out.
Your idea of doing more programmatic debugging is a good one, but it's hard to make it all work nicely. As you found, some gdb commands (basically those related to inferior control) don't work in commands. Also, it just isn't nearly as convenient.
You can go further that direction. For example you could use SystemTap to probe the program instead.
However there are also nicer approaches.
One way is to run the inferior using a virtual X server -- a nested one, or one running in a VM. Then you can escape to the "outer" X server for debugging. This will be much nicer.
Another way is to have two computers, and run the debugger on one and the inferior on the other. In a way this is really the same answer, just using a real machine rather than a virtual one.
The question is old, but for anyone that may be struggling with this issue, there is a way to stop the freezing behaviour from happening by disabling the X server grab.
You have to change the config in your IDE to run the program with the following system property:
-Dsun.awt.disablegrab=true
If you are using javaws (Java Web Start) to run the application use:
-J-Dsun.awt.disablegrab=true
instead.
This scenario has come up before and I'm wondering if there is any way I can determine where the actively running form is executing within code? The problem is when I inherit a very large application which I'm not totally familiar with yet and I have it running through VS.NET 2010. I might have a particular screen up and go "geeze it would be nice if I could start debugging when I do 'x'".
If this was a simple form with some buttons I wouldn't even bother asking here; I'm not that novice. But the time consuming task is when I look at a tabbed screen in a large multi-project solution with drag and drop capabilities, right click options, etc. and have to spend 5-10 minutes tracking down where to place a breakpoint to debug.
What I'm wondering is if there is a way to have the WinForms app running via IDE and do 'something' that tells VS.NET on the next action break into the code (obviously without a breakpoint because I don't know where to place one yet). This would save me a ton of time trying to track down which event is occurring in a not so simple form or series of forms.
I hope this makes sense...
Thanks!
Yes, that's somewhat possible. When you use Debug + Break All then the 99.9% odds are that you don't break into code that's part of the project. A Winforms app is normally idle, pumping the message loop and waiting for Windows to tell it that something happened. You'll break at the Application.Run() statement.
The trick to then use Debug + Step Over. The program resumes running like normal. Then give a UI command (do 'x' in your question) and the debugger will break at the first statement of real code, typically at the start of the event handler for that command. It isn't exactly guaranteed that that code would be relevant, you might break at a MouseMove event handler for example. So YMMV.
I am kind of lost here, and I don't know what to do
I have a problem that I don't know what the source of it.
We have a large wpf application, that is built similar to prism (composite application)
Actually we are using lots of prism library.
I wrote a module to replace an existing module.
And the application now is loading my module, instead of the old module.
I start to notice, with the new module, that sometimes the application freeze for 20-30 seconds without any response, and then it work smoothly after that.
The freeze is not consistent, and there is no pattern or a specific reason that cause it.
I am suspecting that could be my module that is causing that freeze.
But at the same time, many other developers introduced new code to the application.
My question is there a way to trace that freeze?
Is there a way to compare the old module and the new module that I wrote?
I can run the application with my module, and trace the application, and then I can change the config file to load the old module.
Is there a way to compare between the two?
Should I do profiling?
and if profiling will help, then what should I look for?
any other tool could help?
Thanks a lot for any reply
It sounds like you are doing a long running operation on your UI thread. Are you making any database / webservice calls from the main thread? I think one of the easiest things to do is run it in the debugger, and when it freezes, hit the "pause" button. Visual Studio will pause execution at the current location, and you can examine what is taking so long.
If the problem isn't immediately obvious there, I would definitely start profiling the application to track this down.
A WPF application. Debugging. Stop on break point.
After few seconds Visual Studio (2008) spontaneously aborts the application execution.
It is never mind what I do after stop on break point: even if I do nothing.
With very simple test WPF application everything is OK with debugging.
Any ideas?
When an application aborts that quickly without warning it's usually the result of a stack overflow in the process. This makes it difficult (if even possible) to do tear downs operations like bringing up Dr Watson.
One thing I didn't quite understand is if the application or VS is suddenly stopping.
If it's the application there is likely a StackOverflow occurring in such a way that VS can't trap the exception. Try disabling Just My Code debugging, turn off implicit function evaluation and break on first chance exceptions. That should hopefully help reveal the problem.
The problem was solved.
To solve the problem the debug settings must be changed:debug->exceptions: and check on exceptions boxes (I checked on C++ and CLR).
(source: ggpht.com)
Result: I can see exception that I didn't see before and I can normally debug my application.
The reason was incorrect vcshost.config file name (my fault).
I know that running applications in DEBUG (build configuration) thru the visual studio adds a level of overhead but I have a WPF application that I am testing out that is painfully slow in its execution and other functions such as drag/drop of items. When I run the application in Release mode it performs like one would expect, very quickly and without hesitation. I've set up no special debugging parameters or any other watches, settings or breakpoints that would interrupt the application.
Has anyone else run across an issue like this or is there possibly just some setting that can be adjusted? It's not really an issue more of a why is this happening...
thanks.
The garbage collector is much less aggressive in debug mode.
Try watching the memory usage in task manager, the VM Size column is often the most useful.
See if during the slow operations a lot of memory gets released - this will indicate that the collector hasn't bothered doing much work for a while and then has had to kick in a do a larger clean up.
You might check your Output and Immediate windows. You're might be getting a lot of messages thrown in there, especially if you're getting binding errors.