Question

I know there is no WINAPI which would do it, but if a thread is hung and holds an open handle of file. how do we determine the thread id and Terminate it within our processes.

I m not talking about releasing file locks in other processes but within my own process.

it could also be possible that thread has crashed / terminated without closing the handle.

Answer 1

You cannot determine which thread holds an open handle to a file. Nearly all kernel handles, including file handles, are not associated with a thread but only with a process (mutexes are an exception - they have a concept of an owning thread.)

Suppose I have the following code. Which thread "owns" the file handle?

void FuncCalledOnThread1()
{
     HANDLE file = CreateFile(...);

     // Hand off to a background thread.
     PostWorkItemToOtherThread(FuncCalledOnThread2, file);
}

void FuncCalledOnThread2(HANDLE file)
{
       DoSomethingWithFile(file);
       CloseHandle(file);
}

Answer 2

Use Process Explorer - http://technet.microsoft.com/en-us/sysinternals/bb896653.aspx [edit, or Handle - http://technet.microsoft.com/en-us/sysinternals/bb896655.aspx ]

Answer 3

You could attach to the process with the debugger when this happens, pause the program, search for the thread that caused this, and, traversing the stack, find out what it s doing, which code it executes, and which variables are on the stack.

If you used RAII for locking, this should be enough, as the lock must be on the stack.

Answer 4

I haven t seen anything browsing MSDN, although there s certainly something perhaps undocumented out there that can give you the information you need.

If your threads are creating these resources, and there s an expectation that one of these threads might go out to lunch, would it make more sense for them to query resources from a utility thread who s sole job is to create and dispose of resources? Such a thread would be unlikely to crash, and you would always know, in case of a crash, that the resource thread is in fact the owner of these handles.

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