April 5th, 2019

What does it mean when my attempt to stop a Windows NT service fails with ERROR_BROKEN_PIPE?

Raymond Chen
Raymond Chen

A customer reported that they had a sporadic problem: Their product includes a Windows NT service, and when their client program tries to stop the service, it sometimes fails with ERROR_BROKEN_PIPE. Their client program is written in C#, so it uses the Service­Controller.Stop method to stop the service, and the failure is reported in the form of an exception. In Win32, this turns into a call to the Control­Service function with the SERVICE_CONTROL_STOP code.

Under what conditions would an attempt to stop a service result in the error ERROR_BROKEN_PIPE?

One of the developer support escalation engineers used psychic powers:

Does your service terminate itself before the call to its Handler­Ex routine returns from the SERVICE_CONTROL_STOP request, or before the call to Start­Service­Ctrl­Dispatcher returns?

I’m guessing that the ERROR_BROKEN_PIPE arises because the service process terminated itself while the Service Control Manager was still talking to it, waiting for the service to report that it finished processing the SERVICE_CONTROL_STOP request. The error is ERROR_BROKEN_PIPE because the process on the other end of the pipe (the service) died.

The customer agreed that this was a possibility: When the service receives the SERVICE_CONTROL_STOP request, it signals a helper thread to clean up, and that helper thread may finish its cleanup and terminate the service process before the main thread can report a successful stop to the Service Control Manager.

A short time later, the customer reported back and confirmed that when they forced the race condition to occur, they indeed got the ERROR_BROKEN_PIPE error code.

I like this example of psychic debugging because it demonstrates how you can take something you know (ERROR_BROKEN_PIPE means that two processes were talking to each other over a pipe, and one side suddenly terminated), and think about how it could apply to something you don’t know (surmising that the Service Control Manager uses a pipe to talk to the service).

Category
Old New Thing
Topics
Code

Author

Raymond Chen

Raymond has been involved in the evolution of Windows for more than 30 years. In 2003, he began a Web site known as The Old New Thing which has grown in popularity far beyond his wildest imagination, a development which still gives him the heebie-jeebies. The Web site spawned a book, coincidentally also titled The Old New Thing (Addison Wesley 2007). He occasionally appears on the Windows Dev Docs Twitter account to tell stories which convey no useful information.

5 comments

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  • Joshua Hudson

    This actually is the tip of a really bad design in the service manager.
    StopService(...);
    CreateFile(serviceprocessbinary, ... CREATE_ALWAYS ...); // Error file in use.
    The correct fix would be to call TerminateProcess(GetCurrentProcess(), 0) on getting SERVICE_STOP but the service manager reports rather than success. I could handle it, but services.msc doesn't. Hint: if you get that service isn't running anymore.

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  • Ian Boyd

    It is also extraordinarily satisfying when you have an actual solution the explains the problem. Computers aren't magical: it's doing something exactly rational and explainable.

    What isn't fun if when there diagnostic steps are: have you tried running a virus scan? Have you tried sfc /scannow? Have you tried rebooting? Have you tried deleting your user profile and creating a new one? Have you tried reinstalling Windows?
    Aside from the last two (which I simply will...

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    • Adam Rosenfield

      Deleting your user profile is unlikely to help (and painful to reverse), but creating a new, clean user profile is a cheap and easy diagnostic step if you've exhausted other options.
      I once ran into a problem with Visual Studio that I couldn't explain.  (I forget the details, but they're not important.)  Uninstalling and reinstalling VS didn't resolve it.  But when I created a new user profile and logged in as that user, the problem...

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  • Keith Patrick

    I've gotten this specific error before, so when I see something like this, it's usually more of a matter of remembering how i fixed it in the first place. Unfortunately, I never got around to putting together a personal knowledge base for these errors, so I have to count on my unreliable memory, but in this case, I remembered the error message immediately.
    I tend to use psychic (or intuitive) debugging more for multithreading, looping...

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  • Henry Skoglund

    Hi, been a while since you wrote about psychic debugging! I just want to thank you for introducing that method of debugging, it's been useful for me too. It's kind of taking a holistic view of the whole problem, while also paying attention to all the small details that surrounds it.
    One additional method I resort to: "Whatever remains, however improbable, is the solution.". That quote from Sherlock Holmes has also served me well during...

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