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How can glfwSleep () cause a segfault?

in my multitasking application, I am using the sleep () function (one from the GLFW library):

glfwSleep(..);

and this appears to cause my application to segfault as my call stack shows:

#0 76CFC2BC WaitForSingleObjectEx() (C:\Windows\system32\kernel32.dll:??)
#1 00000016 ??() (??:??)
#2 0000006C ??() (??:??)
#3 00000000 ??() (??:??)

glfwSleep()

used inside a stream. This is dangerous? Why is my program undergoing major changes?

Edit:

When the parameter glfwSleep()

is <0.02 (secs) it is not a segfault!

Edit 2:

From GLFW official documentation:

Writing threaded apps can be very awkward before getting used to it, but there are a few key rules that are simple enough:

  • ALWAYS provide exclusive access to data that is shared by threads!
  • Make sure the streams are synchronized correctly.
  • NEVER wait!

I think I got my answer. Now find an alternative.

Thanks!

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3 answers


From the GLFW wiki :



GLFW does not work with GHC threads, forkIO, or threadDelay. So avoid them if you can.

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Is the caller's glfwSleep () threading thread segfault'ed?



it seems that the crash was caused by the WaitForMultipleObjectsEx API call. are you specifying and passing the correct objects and timing numbers to WaitForMultipleObjectsEx?

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To quote the Pragmatic Programmer ,

`` select Isnt Broken

It's rare to find a bug in the OS or compiler, or even a third party product or library. The probability of an error in the application.

Why does your program call WaitForSingleObjectEx()

when it glfwSleep()

calls Sleep()

? Well, even if you don't have the source code Sleep()

, it's not a completely black box. Parse Sleep()

it and you will probably see (depending on which version of Windows you have) that Sleep()

either calls or tail-calls SleepEx()

. In XP, it SleepEx()

calls NtDelayExecutionThread()

, and in Vista it calls WaitForSingleObjectEx()

.

So what happened to the rest of your stack? 00000016, 0000006C and 00000000 are invalid return addresses. I wouldn't be surprised if, somewhere in your code, you are passing a pointer to a stack-allocated buffer to another thread, and while your program is sleeping, that other thread mangles the first stack of the thread. Step in Sleep()

, place a memory breakpoint on the return address and you can catch the culprit.

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