I'm facing an extremely weird bug here and I'm not really sure If I'm following the right path to solving it or even how to solve it.
Here is the problem I'm facing: I start debugging a WPF application which uses log4net, NHibernate and LINQ to NHibernate, and when I try to get an Entity from the database my application and sometimes VS hang for a lot of time, and after a while an exception dialog opens showing a message containing the following information on a ContextSwitchDeadlock MDA:
The CLR has been unable to transition from COM context 0x34fc1a0 to COM context 0x34fc258 for 60 seconds. The thread that owns the destination context/apartment is most likely either doing a non pumping wait or processing a very long running operation without pumping Windows messages. This situation generally has a negative performance impact and may even lead to the application becoming non responsive or memory usage accumulating continually over time. To avoid this
I copied the code files to a new project and deleted the old project to see If I could make this message disappear, thinking it had something to do with my configuration. I started adding few things at a time to see what was causing it, and when I included log4net configuration code the bug appeared again. First I included it through AssemblyInfo and later trough code configuration on application startup, and absolutely nothing changed at all :(
So, here are my findings:
It only happens when I'm using log4net.
It happens when NHibernate loads an Entity from database (lazy loading).
I don't know what might be the source of this bug. It only happens when debugging in Visual Studio. I've tried following the steps on the "Enabling and Disabling MDAs" section of the following page: http://msdn.microsoft.com/en-us/library/d21c150d.aspx, but that doesn't work either, VS still hangs and it's memory usage increases.
When I run the program normally none of this happens, so I'm pretty sure this is not a deadlock situation, as this question suggests: contextswitchdeadlock (I've also tried the solutions posted there).
Because of that, I've decided to disable log4net and enable it again when deploying my app.
I'm posting this question to find out if somebody else has faced this bug or if somebody has some suggestions on how to solve it. Finally, it might help somebody else facing this very same problem.
When using the DebugAppender all the entities in the databases are loaded and all its data written to the debug output. That was causing the ContextSwitchDeadlock MDA since it tookmore than 60 seconds to run.
Disabling the DebugAppender solved my problem.
Thanks to Mauricio Scheffer for the tip.
Related
Today I came across a bug that I'd like to share with everyone.
When trying to execute an SSIS package in Visual Studio (2015 and 2017 the following can happen (note this package was executed sucessfully before).
While on the bottom it clearly says the SSIS package is finished, the data flow task is still in progress (and will never finish). What also happens (don't know if consistently) a CMD window pops open with "SQLDUMPER.EXE".
This is not due to the way the steps are configured, since executing them individually might still lead to the proper results.
Note as well that in my case this problem makes Visual Studio incredibly unstable. It is not uncommon that after or during every execution Visual Studio crashes completely and is automatically shut down by Windows.
There are no error messages and I had no idea what the reason is this happened untill... (answer below)
After a lot of googling i've found a reason whya multitude of people seem to have this problem.
Right click the project and then click on properties
Click "Debugging"
Set "Run64BitRunTime" to "True"
Apparently for most people this fixes the problem.
For me however I had to come up with another solution.
Right click the project and click on properties
Click "General"
Set "TargetServerVersion" to either the target SQL server and run the package again OR set it to any SQL server version, run the package to see if it works, and if it doesn't set it to another version.
These solutions are counter intuitive because this problem seems to arrise at a random moment and the target sql server version might have been the same throughout the entire development.
I have not tried to see what happens when I deploy the bugged project to a server and see if it runs there, so any and all extra information on this problem would be appreciated.
I spent a good bit of time googling this problem. It looks like it is being reported by many people around the world. It is usually down to either x32/x64 compatibility or some miniscule issue with sorting or data sizes or compiling a custom C# script (or combination thereof).
None of these things worked for me so I rebuilt the entire package from scratch and the issue was gone.
It is far from perfect, especially if your package is large and/or complex but if nothing else works, this is your last resort.
"Run64BitRunTime" was already set to "True", but I was getting this error. so I restarted the visual studio and problem resolved.
None of the proposed solutions worked for me. I had to rebuild both the solution and the project a couple of times and this fixed it. Of course, I opened and closed the VS a couple of times in between. I guess this is a bug and you have to tinker with it to get it to work.
We have built a website based on the design of the Kigg project on CodePlex:
http://kigg.codeplex.com/releases/view/28200
Basically, the code uses the repository pattern, with a repository implementation based on Linq-To-Sql. Full source code can be found at the link above.
The site has been running for some time now and just about a year ago we started to get errors like:
There is already an open DataReader associated with this Command which must be closed first.
ExecuteNonQuery requires an open and available Connection. The connection's current state is closed.
These are the closest error examples I can find based on my memory. These errors started to occur when the site traffic started to pick up. After banging my head against the wall, I figured out assumed that the problem is inherit within Linq-To-Sql and how we are using the same connection to call multiple commands in a single web request.
Evenually, I discovered MARS (Multiple Active Result Sets) and added that to the data context's connection string and like magic, all of my errors went away.
Now, fast forward about 1 year and the site traffic has increased tremendously. Every week or so, I will get an error in SQL Server that reads:
A severe error occurred on the current command. The results, if any, should be discarded
Immediately after this error, I receive hundreds to thousands of InvalidCastException errors in the error logs. Basically, this error shows up for each and every call to the Linq-To-Sql data context. Only after I restart the web server do these errors clear up.
I read a post on the Micosoft Support site that descrived my problem (minus the InvalidCastException errors) and stating the solution is that if I'm going to use MARS that I should also use Asncronous Processing=True. I tried this, but it did not solve my problem either.
Not really sure where to go from here. Hopefully someone here has seen and solved this problem before.
I have the same issue. Once the errors start, I have to restart the IIS Application Pool to fix.
I have not been able to reproduce the bug in dev despite trying many different scenarios involving multi-threading, leaving connections open, etc etc.
One possible lead I do have is that amongst the errors in the server Event Log is an OutOfMemoryException for the Application Pool. Perhaps this is the underlying cause of the spurious SQL Datareader errors (a memory leak elsewhere). Although again I haven't been able to reproduce this in dev.
Obviously if you are using a 64 bit OS then this is probably not the cause in your case.
So after much refactoring and re-architecting, we figured out that problem all along is MARS (Multiple Active Result Sets) itself. Not sure why or what happens exactly but MARS somehow gets result sets mixed up and doesn't recover until the web app is restarted.
We removed MARS and the errors stopped.
If I remember correctly, we added MARS to solve the problem where a connection/command was already closed using LinqToSql and we tried to access an object graph that hadn't been loaded. Without MARS, we'd get an error. But when we added MARS, it seemed to not care about it. This is really a great example of us not really understanding what the heck we were doing and we learned some valuable (and expensive) lessons from this.
Hope this helps others who have experienced this.
Thanks to all how have contributed their comments and answers.
I understand you figured out the solution..
Following is not a direct solution to the problem; but it is good for others to take a look at
What does "A severe error occurred on the current command. The results, if any, should be discarded." SQL Azure error mean?
http://social.msdn.microsoft.com/Forums/en-US/bbe589f8-e0eb-402e-b374-dbc74a089afc/severe-error-in-current-command-during-datareaderread
Stumped here. Posted a similar question before. We have a pretty large WPF app that on some machines runs great, but on others, all of a sudden, one of the CPU cores gets pinned at 100% (just one core) and the app freezes. It usually seems to happen when showing a context menu or a combobox drop-down (i.e. Popup controls) which is why we can't debug this since no user code is executing at that time. It's driving us crazy because again, on most machines it runs fine, but on a few, it freezes.
The odd thing is when we run it in a VM, it runs great there too! Crazy! Not sure what's causing this, or more importantly, where to even begin to look because as I said, no user code is running.
This happens on only about 10% of our machines, but it consistently happens on those machines. All are clean (i.e. relatively fresh OS installs, no crazy apps, etc.) and mostly identical machines spec-wise: similar CPUs, similar RAM, same video drivers and service packs.
So as I stated in the title, can anyone suggest possible reasons why a WPF app would pin the CPU and lock the app on some computers but not others? We're just stumped!
Found it!! Turns out there's a bug in .NET 4.0 regarding UI Automation and the changes MS introduced. Here's the info, and the fix! (Note: Even if you call MS, they will send you a link, but it's always a broken link. I managed to track this down manually.)
Note: Their article talks about a specific case that causes this behavior, but if you google around, you'll see tons of issues around hangs related to those DLLs. The latest is they're promising a fix in the .NET 4.5 runtime (from a MS post on this issue.)
Here's the KB article...
http://support.microsoft.com/kb/2484841/en-us
...and here is the actual hotfix.
http://archive.msdn.microsoft.com/KB2484841/Release/ProjectReleases.aspx?ReleaseId=5583
Crappy video driver? Pull two machines - one where it happens, one where not, and start analyzing differences. Could be hardware defects, bad video drivers, anything in that area. WPF uses the GPU to render if one is there.
Since you seem quite to lack options, i would advice to make a new project with just most basic ComboBox in the Window, doing almost nothing. This should work (check :-) ). Then you add features one by one in the ComboBox and test, for instance when you add command, start with empty one. Do this until it 'breaks'. So you know which feature is the culprit.
You didn t say if all was working with software rendering.
Bear with a bit me before jumping straight to the normal caching fix solutions. Here's what happening:
I have a project, a single project out of dozens in our solution that appears to be refusing to update its code when I build and run. It's not part of the xap, but a dll sitting along side the xap.
Things I've already determined not a solution:
I've checked the output of its dll and it has been built, and its contents updated to match my code, verified with dotPeek. But it refuses to display the updated code.
I clean, rebuild the solution, and restart the dev server but it refuses to display the updated code.
I switch to a different browser, no dice.
I clear browser cache's to no avail.
I completely delete my local code and do a fresh fetch from our repository, again, no love from silverlight.
I have not been without a little success though. The ONE bone I've been thrown was over the weekend. Not touching it for a couple days, I came back to work on Monday and, without having done anything to it, it just updated. Now, however, it's cached again, or something, because it's stuck in the last set of changes I made to it.
So my question is this: What am I missing?
Most likely your files may be read only and MS Build fails to display error message and it does not update files. In case if you have mistakenly checked in your .xap files, then this is possible, you will have to remove it from your source control and also make .xap file writable by removing readonly checkbox.
Visual Studio checks in your .xap files by mistake and silverlight build does not report any error.
Second, do you have any other file backup service installed like Shadow copy or Dropbox kind of online backup service, something is probably making xap files readonly and that is causing this problem.
Here there are couple answers: Prevent Silverlight 3 from caching while debugging
Code below helped me(add this to Page_Load of page that hosted the app ):
Response.Cache.SetExpires(DateTime.Now.AddSeconds(-100));
Response.Cache.SetCacheability(HttpCacheability.NoCache);
UPDATE:
Prevent Silverlight xap from being cached by proxy server
"So my question is this: What am I missing?"
An internal caching mechanism that our application uses. So, none of you could really have helped me as it was an architectural feature of our software.
I have a standalone WPF application running on .NET 3.5. Every so often, the display simply freezes up for several seconds. This is most noticeable on screens where something is being updated often. Here is a video showing the problem.
While the display is frozen, the interface remains responsive (video).
I've come across some other posts with similar problems who attributed it to a SW/HW rendering issue. To be safe, I disabled HW rendering altogether, but still have the problem.
I ran a file monitor during the freezes to see if there is some extraordinary file access or activity going on, but nothing is out of the ordinary.
Final note: The target platform is a small touch-screen panel PC without much memory or horsepower (512 MB). I only see this issue on the target, never on my development PC, which has much more in the way of resources.
UPDATE
I thought I had fixed the issue by removing some animation code, but it did not work. I am still encountering the problem and I'm at the end of my rope.
Here's some more things I've tried:
Upgraded to .NET 4.0. Same behavior.
Added debug code to all methods that may be invoked via DispatcherTimer (which are called on the UI thread) to make sure none of them are holding up the UI.
I'm really stumped here and have added a bounty. As I mentioned, the problem only occurs on the target PC (link).
I tend to suspect either .NET GC or the OS swapfile when this kind of behavior shows up.
For the former, you could try the .NET performance counters to monitor for suspect activity.
If the device has a swap file, you can disable it and see if the behavior changes.
As others have said, a profiler (or some what of isolating what condition is inducing the delay - even just attaching and breaking the debugger when it occurs) would be a good way to get more information.
Did you tried to profile the application on the tested system? Using a memory and/or performance profiler?
You could get some good informations out of this type of test : some .Net profilers
And here's one for WPF : WPF profiler from microsoft
The culprit was the following method call:
new HwndSource(new HwndSourceParameters());
This was added to my application because it patched a memory leak problem in .NET 3.5. This work-around can be found here. If I remove this call, the rendering issues go away.
I took out the call and fixed the memory leak in another way (removing storyboard animation and using code behind instead)