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I have a class Class in which there's a member property HANDLE handle to a thread (We can assume it is set to NULL at that point) . at some point , a method within Class dispatches one of it's own methods Class::threaded() (using another function that is external to the class itself, but it doesn't really matter here) with CreateThread(). The calling thread will then may continue to other function outside of Class.

As CloseHandle() must be called for the HANDLE returned from CreateThread() , I was wondering if calling it from Class::threaded() just before it returns would be a decent solution.

Edgar James luffternstat
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  • As you've marked this as C++ you should use `_beginthread` or `_beginthreadex`. See the `CreateThread` docs: "A thread in an executable that calls the C run-time library (CRT) should use the _beginthreadex and _endthreadex functions for thread management rather than CreateThread and ExitThread;" – Steve Nov 27 '13 at 22:49
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    That's advice from the previous century. The CRT has been tweaked to deal with this, rather necessary to support thread-pool threads where you of course can never call _beginthreadex. It now allocates thread-local data on-the-fly when needed. – Hans Passant Nov 28 '13 at 13:42

3 Answers3

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Two basic ways to deal with a thread. Commonly you're interested when the thread terminates, you'll need to keep the handle around so you can find out. And of course you'll close it after you detected termination. Or you don't care, fire-and-forget style, or have additional synchronization objects to signal that the thread function completed and/or you ask it to exit. In which case you simply close the handle as soon as you start it.

Do keep in mind that it is not necessary to keep the handle opened to keep the thread running, in case that's the source of the confusion.

Hans Passant
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You receive a handle to the thread so you can manage it. If there is no need to it, you can call CloseHandle right away.

Closing the HANDLE will have no terminate the thread, so, it's secure to close it if nothing from the thread is of interest to you.

fernando.reyes
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    The thread `HANDLE` is often used for synchronization as well, not just management. You might want to add, that closing the `HANDLE` does not terminate the thread. – IInspectable Nov 27 '13 at 22:34
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You can close it as soon as you are through using it. Closing it has no effect on the thread. (The handle is reference counted by OS.)

ScottMcP-MVP
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