Re: [Xen-devel] "xm save" trouble -- deadlock?

[Gerd Knorr <kraxel@xxxxxxx>]

> >   master-xen root /vm/ttylinux# strace -p6568
> >   Process 6568 attached - interrupt to quit
> >   select(4, [3], [], [], {0, 960000})     = 0 (Timeout)
> >   futex(0x80e53b8, FUTEX_WAKE, 1)         = 0
> >   accept(3, 0x408193f8, [110])            = -1 EAGAIN (Resource 
> > temporarily unavailable)
> > There is no point in calling accept(3) unless select() flags file handle 
> > #3 as readable.
> This mindboggling piece of loveliness is in xen/web/connection.py.  If you can
> unpick it, a patch would be more than welcome!
Can someone explain the comment on the start of the file?

<quote>
   """We make sockets non-blocking so that operations like accept()
   don't block. We also select on a timeout. Otherwise we have no way
   of getting the threads to shutdown.
   """
</quote>

What exactly is the thread shutdown problem here?  Why the timeout is 
needed in the first place?
cheers,

  Gerd

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