I have a third party application that sometimes hangs (no crash just taking 100% CPU). I think this hanging is related to remote desktop (specifically the rdpclip.exe task) sometimes messing up / locking the clipboard. As this is very difficult for me to reproduce for me, I as wondering if anyone is aware of the remote desktop clipboard issue and knows what exactly is happening when rdpclip.exe messes up the clipboard (it seems to be relatively common, happening a maybe once a week). Ideally I would like to write a little programm that replicates this issue so that I can reproduce my application hanging problem at will.
Would be very grateful for any pointers you could give me.
Thomas
According to Microsoft this is usually related to a bug in the clipboard view chain. Sometimes application registered into the clipboard chain are terminated without getting unregistered which leaves all other applications in the clipboard chain without that change event.
I would start by trying to replicate that behaviour.
(The usual workaround is to kill the task for rdpclip which are discussed in lots of other threads)
Related
My application started life as a c++ Console application in VS2019. Code was provided as part of an SDK. Worked perfect. Great response from the manufacturer USB device. Later, I wanted to graduate is to a GUI application, much as I've been doing in VB and c#. Lo and behold, I managed to reconstruct the application in both Qt and Win32 but I'm running into a situation where the application becomes unresponsive and I have no way to tell what's going on.
In the Console application, I have to execute this code to interface with the device AFTER sending a "TakeMeasurement" command :
if (SDK_SUCCESSFUL(sdkError)) {
printf("\nWaiting for measurement to complete...\n");
while (!isMeasureWait) {
if (isDisConnect) break;
this_thread::sleep_for(chrono::milliseconds(1000));
}
}
This code works like a charm! Ater one or two iteration, the device has completed the measurement and I can get to the data easily.
On the Win32 side, I use the exact same code. Only, once control enters the loop, it never returns.
Any idea how I could diagnose the error? I have the impression that the "timing" is critical, between the exact moment where the Measurement command is initiated to the exact moment the instrument signals that it's done, and the data ready to be picked up.
My naive hypothesis is that, in debug mode on both 'platforms', I must be getting some timing differences? Sadly, I can't get more information from the manufacturer in this regard but I suspect I have a small window of time within which the instrument's response can be acted on? And I begin to suspect that, on Win32, that "time" is too long? Compared to on the Console side?
I was thinking of, perhaps, "measuring" that time, in milliseconds? First, on the Console side, to see what kind of delay "works", and then, to see how the delay compares with the Win32 side.
I may be wasting my time and I sure don't mean to waste yours.
How would I go about getting an idea of time elapsed in a c++ application? I'll take a look around VS2019, they have all kinds of "performance" things that popup at run time?
Any help is appreciated.
I am not sure I completely understand what is going on.
Execution of the thread wait loop was not not the culprit.
I'm not 100% sure but what happens is that, in my 'Export data to CSV TEXT file', if I tried to execute the call to :
SetWindowText(hEditMeasure, wMeasurements);
The application always hung. I placed breakpoints right before the call in the code, to trace execution, and it did not strike me at first but, in VS toolbar, there was a "thread" comboBox? With the value showing = DEVICE.DLL? and to its right, the name of my Export function as the Stackframe. In searching for additional information on the setWindowText function, I came accross the reference to use VM_SETTEXT to send to "different application"? Could it be unknowingly I was sending a message to "another thread", the DLL thread? And that's why it hung? I did not know enough to tell. So I started to move the setWindowText line around, ultimately inside the code that is called by the "Measure" button, and it worked!
I'm not out of the woods yet but I feel I'm making progress. Thank you all for your help and patience.
I have a .net Core web service which seems to slowly increase its cpu usage.
meaning at the first day it won't go past 10%, the second day it can go up to 20% and so on.
Using the TOP command in linux, all my webservices seems to sometime be shown there (probably when a request is made) and afterward disappear.
This specific process after running for a while just stays there constantly consuming cpu even when no request has been made.
the API still working fine, it seems like there are some threads that just keeps hanging and consuming cpu. last time I checked I had 5 threads that consumed 3-4% cpu and didn't die for some reason.
My guess is that in some specific scenario a thread just stays alive consuming cpu.
The app runs on ubuntu machine, my first step was trying to create a dump file with ProcDump so I can analyze those threads and maybe find where they are hanging.
ProcDump generates a huge 21gb file, which trying to analyze with lldb throws out of memory exception. even tried transferring it to a windows machine to debug with windbg , no help there as it couldn't open the file.
As there is no specific exception or anything I can't really share any piece of code as I have no idea where the issue is... just kind a hoping for some suggestion that might help me get to a solution or at least understand where the problem is.
Thanks a lot for reading, cheers
You could try using something like jetBrains’ DotMemory, they also have a fairly high level but helpful guide https://www.jetbrains.com/help/dotmemory/How_to_Find_a_Memory_Leak.html it also worth checking your startup file and double checking the services you’ve registered are used in the correct way ie not added as scoped when they should be transient or even a singleton etc
so iv'e been at it for a while.
Eventually found out that my problem was with HttpClient
Probably some bad mix of static class and creating new instances of HttpClient that causes the issue Iv'e explained above.
Solved it by utilizing HttpClientFactory as explained here -
https://learn.microsoft.com/en-us/aspnet/core/fundamentals/http-requests?view=aspnetcore-2.1
Lesson learned :)
A little late but Procdump for Linux just added .NET Core 3 support that generates much more managable sized core dumps. It automatically detects if the target process is .NET Core and does the right thing (i.e., no need to specify switches).
I am trying to figure out a "Failed to resume in time" problem. In one of our testers devices (which is an iPhone 4S with the latest OS) it happens very frequently, whereas in my own device it doesn't seem to happen at all.
Anyway, I got a few crashlogs. I am unable to trace the root of the cause though. I understand that the issue might be
1.When a process is holding up the main thread for too long.
2.When there is a memory issue.
I don't think the memory is much of an issue since it seems to happen when the user leaves the main menu and comes back. Nothing much is happening in the main menu so it probably is a task that runs too long.
Here is an excerpt from the crash log:
Can somebody help me or guide me on who I can trace the cause of the issue? Is there anyway to turn off the watchdog timer(probably not huh?) Also, what does highlighted thread refer to?
I have already checked my applicationDidBecomeActive & applicationWillEnterForeground to make sure there is nothing going on there.
To my knowledge there are no synchronous calls being made at this point. Does Reachability use synchronous calls to check for internet? How can I check for that?
I am not making any large data transfers upon resume.
I notice that GameCenter automatically logs in or check for log in upon resuming your app. Is there anyway to prevent this? Could this possibly cause a time out issue?
I tried doing a time profile, but I am not able to understand how to use it to analyze. If you can provide a good resource for that, that would be amazing.
Thanks!!!
You're currently in "trying to find the issue mode". You should switch to "try to find out how much of an issue this really is" mode.
So go find another 4S (actually as many as you can) to rule out that it's a device-specific issue. If it happens on all 4S it should be easier to pinpoint. If not, have someone else look over it, discuss possible causes. The peer programming approach often helps when you're stuck in a dead-end situation.
If the issue is only on that one device, you might want to check if it's broken (or "jailbroken") or might simply need a hard reboot (hold power and home for 10+ seconds).
If it only happens on some devices but not all, try to find what they have in common. This could be language/locale, or dictation, practically any kind of setting the user might have changed. If necessary, write a logger that logs as many settings as possible to your (web) server so you can compare settings one-by-one and quickly discard those that aren't in synch.
If only very few devices are affected, you could also ignore the issue and hope that additional crash logs from users will reveal the key to the issue.
Finally, there's always the option to disable suspend on terminate and instead terminate the app when the home button is pressed (as it was pre iOS 4). Unless of course the app has to run in background.
I'm working on a bug where I have an MFC application that does weird things when installed in when Sophos Safeguard hard drive encryption is installed. I'm sorry to be so vague here, but I'm writing this away from the office so this is all from my (poor) memory.
Three things I've noticed:
AfxGetResourceHandle() doesn't return a consistent resource handle. There is a single case where we try to load a string resource, and for some reason, the resource handle that we get from this method is different to all the other stings.
Can't construct a CDocumentTemplate. There is a trace error which I cant seem to recall. Will edit and post when I'm in tomorrow.
This behaviour appears to manifest in a Visual Studio 2005 version of the project, but not a Visual Studio 2008 version. Unfortunately moving to the 2008 version is not an option.
The bug is not always reproducable if I step through with a debugger. Also, bringing up debug message boxes changes the behaviuor, which leads me to think that either there is some kind of race condition going on with the way MFC events are being handled, but I'm not sure how I'll ever know for sure, or even what I can do about it if I did.
I think there's some underlying reason that the app is behaving weirdly, but what I've posted are more symptoms. Can anyone think of what I should check for?
I've run Windows update on the test environment to ensure everything was up to date, and I've examined the process in procmon to see if the disk encryption stuff was getting in the way and conflicting with files - it didn't appear to be, but it does appear to be involved in some way as our app accesses Sophos related paths in the temp directory.
If your code is multithreaded (which I assume it is, since you mentioned the possibility of a race condition), then the likelihood is that the decryption delays are exposing concurrency flaws. You might want to try running the application off of a network share or similar slow access device to see if it manifests similar problems.
Turned out that the antivirus software was injecting itself in a way where the antivirus' software's resource handles were overridng the app's resource handles. Yuck!
This is something that's been bothering me a while and there just has to be a solution to this. Every time I call ShellExecute to open an external file (be it a document, executable or a URL) this causes a very long lockup in my program before ShellExecute spawns the new process and returns. Does anyone know how to solve or work around this?
EDIT: And as the tags might indicate, this is on Win32 using C++.
I don't know what is causing it, but Mark Russinovich (of sysinternal's fame) has a really great blog where he explains how to debug these kinds of things. A good one to look at for you would be The Case of the Delayed Windows Vista File Open Dialogs, where he debugged a similar issue using only process explorer (it turned out to be a problem accessing the domain). You can of course do similar things using a regular windows debugger.
You problem is probably not the same as his, but using these techniques may help you get closer to the source of the problem. I suggest invoking the CreateProcess call and then capturing a few stack traces and seeing where it appears to be hung.
The Case of the Process Startup Delays might be even more relevant for you.
Are you multithreaded?
I've seen issues with opening files with ShellExecute. Not executables, but files associated an application - usually MS Office. Applications that used DDE to open their files did some of broadcast of a message to all threads in all (well, I don't know if it was all...) programs. Since I wasn't pumping messages in worker threads in my application I'd hang the shell (and the opening of the file) for some time. It eventually timed out waiting for me to process the message and the application would launch and open the file.
I recall using PeekMessage in a loop to just remove messages in the queue for that worker thread. I always assumed there was a way to avoid this in another way, maybe create the thread differently as to never be the target of messages?
Update
It must have not just been any thread that was doing this but one servicing a window. Raymond (link 1) knows all (link 2). I bet either CoInitialize (single threaded apartment) or something in MFC created a hidden window for the thread.