I have been tracing a BAD_ACCESS error using NSZombieEnabled. As error I get returned:
*** -[MyDocument respondsToSelector:]: message sent to deallocated instance 0x2671b0
I do know what this means,however what surprises me is that I don't call this function anywhere, not in MyDocument.m nor in any imported files.To be exact, I don't call this at all in my whole project. The debugger will not go to the actual code that causes the error, but only shows the assembly code, which, when I click on it, gives me and even bigger list of not understandable numbers.
Does anyone have an idea where this weird "respondsToSelector" could come from? Maybe from frameworks I am using? I am really confused.
Thanks for any help!
respondsToSelector: is widely used in frameworks. For instance, if your class is a delegate or data source (highly likely for MyDocument) the delegating object will use it to determine which delegate methods you support.
In general, the way to find out where a problem like this is happening is to set a breakpoint on objc_exception_throw() (Run->Show->Breakpoints, double-click where it says “Double-Click for Symbol”, type objc_exception_throw) and run under the debugger (Build->Build and Debug - Breakpoints On).
Related
I'm trying to port my console app over to a Blazor app. Everything worked fine inside the console type project, but it's not inside the Blazor project so I'm trying to troubleshoot. The app calls some things from a separate "class library" type project within the same solution.
The troubleshooting process itself is having issues of its own though. After a little bit of confusion I realized that the breakpoints set inside the referenced class library type project's code are not being hit.
Checking to console, I see it gives the error:
L: Unable to insert breakpoint at FtxApi.FtxWebSocketApi/<Test>d__5:MoveNext ():15
Is there anything I need to do (project settings or something) for the debugger to hit these? Or is it not supported at the moment?
Right now I'm just using a lot of Console.Writeline sort of as a workaround/replacement. And I noticed that the Console.Writelines inside the referenced class library type project are being called.. but only up to a certain method call that comes from a third party package. Execution seems to return from that point (nothing is called after it). Not sure what's going wrong there - more troubleshooting is needed, which brings us back to the breakpoints not firing (ideally I'd be able to make use of them).
I understand Blazor is new (and I'm an absolute beginner at using it), so not everything needs or is going to be perfect. I'm asking about the breakpoints kind of out of curiosity (I'd like to get them working but no big deal otherwise).
What I'd really like some insight into is: What might be going on with the code seemingly stopping execution / returning at that one particular method call? The method I'm calling is WebSocket.Open(), from the package WebSocket4Net. As mentioned above, I've tested this before (in a Console app) and it worked fine, so I'm guessing it's somehow related to Blazor which I'm unfamiliar with. I'm unsure how to get any more info to help debug this problem. Any help appreciated.
Edit:
I managed to find a solution to my problem without the use of debugging tools like breakpoints and such (I just used Console.Writeline a lot). I guess Blazor does not support some websocket implementations or something, because I found this error: System.PlatformNotSupportedException: Operation is not supported on this platform. blazor.webassembly.js:1 at System.Net.Sockets.Socket coming from websocket.Open(). I managed to get it working by implementing System.Net.Websockets instead, similar to this. Though my troubleshooting is over (for now), I'm still wondering if it's somehow possible to use breakpoints inside other referenced projects.
There are 2 solutions:
Solution 1: Right-click at Solution, choose Properties, choose Common Properties, Choose Multiple startup project, choose Action Start for Foo.Client, Foo.Server, Foo.Shared . Something like this
See https://blog.magnetismsolutions.com/blog/paulnieuwelaar/2015/04/07/debug-multiple-projects-at-the-same-time-in-visual-studio
Solution 2: Compile SharedProject, attacht PDB for debugging.
https://learn.microsoft.com/en-us/visualstudio/debugger/how-to-debug-an-executable-not-part-of-a-visual-studio-solution?view=vs-2019
I'm developing a frontend of LLVM IR, and want to attach debug information. I already made the %llvm.dbg.declare works, it can track my variable after this declaration. But I do not understand the another %llvm.dbg.value's purpose, can anyone tell me what situation I should use it? or any examples?
llvm.dbg.declare is sufficient if you're building your code without optimizations (which you should really do). In non-optimized code, locals live on the stack (in allocas) and llvm.dbg.declare tells the debugger where to find them
When trying to debug optimized code, things get murkier because locals can be in registers and there's no actual "memory location" the debugger can examine to always know the value of a local. This is where llvm.dbg.value comes in - it can explicitly notify the debugger that a local has changed, and its new value.
Compilation of my code in both modes debug and release is successful. Debug mode execute and works fine, but when i execute release mode, it says "the application was unable to start correctly 0x80000003".
What is this error and why debug mode works fine but not release.
DLLs for debug and release are present in the same directory name "bin". "lib" for both modes also placed in the same directory.
I tried to solve it many ways but not succeeded ? Guide me how to solve this issue? Thanks.
why debug mode works fine but not release
Thre can be many reasons why one build works while another doesn't. The shape and size of data structures can be different because of #ifdef or because the compiler emits different code, the code being executed can be different - again because of constructs like #ifdef or because of the code the compiler is emitting.
That can matter when you've got code with a bug in it. Let's say you've got a bug that miscalculates the length of an array (or the size of a structure or whatever). You do some pointer arithmetic and write some data into memory using that pointer - only you're writing to the wrong place. Whether that mistake breaks your program may depend on what was in the memory you overwrote.
If you're lucky your program crashes almost immediately because what you overwrote was important to some code executed immediately after your bug. If you're only a little bit lucky your program crashes some time later in a completely different part of your program because what you overwrote was important to code far away from your bug. If you're really unlucky your program doesn't crash at all until several years later when a completely unrelated change moves things around in memory so now what you are overwriting suddenly is important.
There are lots of other possible causes of what are sometimes called Heisenbugs
What is this error
One place to look for errors like 0x80000003 is the file WinError.h which you'll find in the SDK you are using (either the one that came with Visual Studio 2010 or one you installed later). Look in WinError.h and you'll find that that E_INVALIDARG is defined to be _HRESULT_TYPEDEF_(0x80000003L).
That doesn't necessarily help though because we we don't know enough about what is returning that error or why it is returning that error or even that your 0x80000003 is in fact an E_INVALIDARG - it could be some other error with the same value, or some piece of code mis-using E_INVALIDARG or something else.
Another possibility is that 0x80000003 is a hard-coded breakpoint exception being thrown - most likely because your program has got to one of those "this should never happen" places where the only thing that makes sense is to throw an exception and crash. If you look in NtStatus.h (in the same place as you found WinError.h) you'll find that STATUS_BREAKPOINT is defined to be ((NTSTATUS)0x80000003L)
how to solve this issue
The trick is to figure what is causing the 0x800000003 (and where in your code it is happening) so you can narrow down why it is happening. Most likely it's an exception but why jump to conclusions?
You can run a release build inside the debugger just as you would run a debug build - that is, build the code using the Release target and then press F5 or Debug | Start Debugging. Look in the Output Window and you may see some information that will help you interpret the error.
You can also use the Debug | Exceptions menu to add a new Win32 Exception with the value 80000003 and set that up to break when thrown rather than to break when unhandled. That way you should stop in the debugger when that exception is thrown (if it is in fact thrown).
Of course it could be that even running your program within a debugger is enough to change things so your problem doesn't occur.
I am getting the following type mismatch error on the following
IF obj.propery THEN
...
END IF
the code I am using is on visual source safe and when other developers run the same project the code runs with no error. The property is actually a string which is where the problem could be. When I debug and test the property i.e.
?obj.propery = True
no errors are thrown which is a bit strange. If I place the cursor over the property it says "True". I have done a bit of searching on the matter and have found that this may have something to do with OPTION STRICT, however I have the same version of the code as the other developers and OPTION STRICT is not OFF, it hasn't been altered in the code at all. Are there any other settings that could affect this execution of code at run time?
It strikes me that there could be an entirely different reason for your Type Mismatch error, especially as you are accessing an object property. I've experienced this error when I have, for some reason, been pointing at a different DLL to that registered. You will find with VB that it registers a DLL "on the fly" when you build it, so you may end up accessing the code somewhere that you did not expect. This may not be the problem in your case, but it is worth exploring.
This was nothing to do with VB6, it was to do with XP Mode and using my user account from another domain as opposed to XPMUser. When I use XPMUser the application runs this is very odd and I am not sure why this is. If anyone has the reason I would love to hear.
So you are sure this is not the case of a boolean being Vrai?
I'd be inclined to be more explicit in your IF condition
IF isempty(obj.property) = false AND isnull(obj.property) = false
BUT
it would be prudent to check that obj isn't null first, before you start accessing its properties....
I have some code which generates a large quantity of ArgumentExceptions on one particular line (which is in a different developer's code, so I can't just change it), which are then caught and handled appropriately.
I'm trying to debug ArgumentExceptions which are happening in a different section of code (and are then caught and handled, so I can't just look at unhandled exceptions).
Is there some way to ignore the ArgumentExceptions originating from that particular other line of code, while still breaking on ArgumentExceptions which are thrown elsewhere?
You might be able to do this, but it depends on how the code you want to debug is located relative to the other developer's code, and whether or not you can modify (but not commit your changes) to his code.
The first thing you'll want to do is, at least temporarily, go to menu Tools -> Options -> Debugging in Visual Studio, and tick the "Just My Code" box. I assume this is available even in Express editions, but it may not be, and if it's not available for you I'm afraid the rest of what I have to say probably won't help.
Anyway, once you have that ticked, you will no longer see break-on-throw notifications for code that isn't "yours." This means code that is from an assembly not in your .sln, or code marked with the [DebuggerNonUserCode] attribute from System.Diagnostics. What I usually do then is temporarily decorate the offending methods with [DebuggerNonUserCode] until I'm done debugging what I need to debug, and then revert those changes before checking in to souce control.
It's not as elegant as I'd like (I'd love a "never break on throws from this site again" checkbox in the exception assistant), but it's better than nothing.
I believe there may be other debugger settings that could interact with how "Just My Code" works, so if this doesn't work for you let me know and I'll try to get a more accurate picture of what my settings look like when I do this.
If you are talking about the "Break On Throw" exception feature then no there is not. It is strictly a type based feature only and does not have any way to control for what section of the code throws the exception.
Your best bet is to just place breakpoints on all of the lines which throw or temporarily suspend throwing an exception from the one place that you care about.
If you know how you are calling it, I would set the break point in your code and then step into (F11) from there. You could also smack the programmer until they fix their code, which would have the effect of making you feel better (unless you are a pacifist) and maybe they won't have so many ArgumentExceptions in their code (which would probably make you feel better even if you are a pacifist).
Sounds like using exceptions as flow control. If the one you're trying to debug occurs later in the program, you can try to attach the debugger later, or you can wait until after the program is running to turn on breaking when an ArgumentException is thrown.
Try to limit the scope as well - if the exception you're interested in derives from but is not exactly ArgumentException, break on that one instead.
Tell the other developer to fix his code.
Edit: In .NET 4, you can attach a handler to the AppDomain.FirstChanceException event, filter out non-ArgumentException excepitons and filter out the bad one based on the call stack.
The links in the comments are great.
i think Conditional Breakpoints are what you're looking for here. You can do this by right clicking your breakpoint and clicking the Condition... menu item.