atexit + threads = bug?

[David Rushby]

>> I would expect...
> The relative order of "Main thread finished." and "T before
> sleep" is purely due to timing accidents...

Sure, I realize that the interactions between threads have no
guaranteed order except what the programmer imposes upon them.  I
should have qualified my statement of expectation more carefully.

> In fact, there are only two orderings you can count on here:
>   T before sleep < T after sleep
>   Main thread finished < atExitFunc called

I understand your explanation and can live with the consequences, but
the atexit docs sure don't prepare the reader for this.

They say, "Functions thus registered are automatically executed upon
normal interpreter termination."  It seems like sophistry to argue that
"normal interpreter termination" has occurred when there are still
threads other than the main thread running.

Suppose that today I promise to donate my body to science "upon my
death", and tomorrow, I'm diagnosed with a gradual but inexorable
illness that will kill me within ten years.  I wouldn't expect to be
strapped down and dissected immediately after hearing the diagnosis, on
the basis that the mere prophecy of my death is tantamount to the death
itself.