On 12/21/2012 07:15 AM, Nick Lowe wrote:
Briefly casting my eye at the test case, as a general point, remember
that these termination APIs all complete asynchronously and I do not
believe it has ever been safe or correct to call another while one is
still pending - you are in undefined, edge case behaviour territory
here.
These comments do not match my understanding of these APIs. MSDN
documentation contradicts some of this as well.
Win32's TerminateThread/ExitThread, that in turn calls the native
NtTerminateThread, only requests cancellation of a thread and returns
immediately.
One has to wait on a handle to the thread know that termination has
completed, for which the synchronise standard access right is
required.
The same is true of Win32's TerminateProcess/ExitProcess, in turn
NtTerminateProcess, where one waits instead on a handle to the
process.
TerminateProcess() is documented to perform error checking and then to
schedule asynchronous termination of the specified process. I would not
be surprised if the asynchronous termination applies even when
GetCurrentProcess() is used to specify the process to terminate, but I
would likewise not be surprised if TerminateProcess() has special
handling for this. I agree that calls to TerminateProcess() might
return before the calling thread/process is terminated. I have not
tried to verify this behavior though.
http://msdn.microsoft.com/en-us/library/windows/desktop/ms686714%28v=vs.85%29.aspx
The MSDN documentation for TerminateThread() does not state that the
termination is carried out asynchronously, but I would not be surprised
if that is the case.
http://msdn.microsoft.com/en-us/library/windows/desktop/ms686717%28v=vs.85%29.aspx
I would be *very* surprised if it is possible for ExitProcess() and
ExitThread() to return (unless the thread is being suspended and its
context manipulated by another process/thread). The MSDN docs for these
do not mention any possibility of return. In addition, the ExitThread()
documentation explicitly states that Windows manages serialization of
calls to ExitProcess() and ExitThread().
<quote>
The ExitProcess, ExitThread, CreateThread, CreateRemoteThread functions,
and a process that is starting (as the result of a CreateProcess call)
are serialized between each other within a process. Only one of these
events can happen in an address space at a time.
</quote>
http://msdn.microsoft.com/en-us/library/windows/desktop/ms682659%28v=vs.85%29.aspx
http://msdn.microsoft.com/en-us/library/windows/desktop/ms682658%28v=vs.85%29.aspx
I read that quote as supporting my assertion that the observed behavior
is a defect in Windows. It appears Windows is failing to serialize the
calls appropriately.
Tom.
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