cvs commit: fptools/ghc/rts HeapStackCheck.h HeapStackCheck.hc PrimOps.hc

[Simon Marlow]

> Simon Marlow <simonmar@glass.cse.ogi.edu> wrote,
>=20
> > simonmar    2001/07/06 07:11:38 PDT
> >=20
> >   Modified files:
> >     ghc/rts              HeapStackCheck.h HeapStackCheck.hc=20
> >                          PrimOps.hc=20
> >   Log:
> >   Fix a couple of nasty bugs in the take/putMVar implementation.
> >  =20
> >   Now we keep the invariant that a full MVar only has=20
> blocked putMVars
> >   on its queue, and an empty MVar only has blocked takeMVars on its
> >   queue.  It was the absence of this invariant that led to=20
> accidental
> >   deadlock before.
> >  =20
> >   The second bug is that there was a window between a blocked thread
> >   being restarted and it actually retrying the takeMVar/putMVar
> >   operation when it could receive an exception, which would=20
> also lead to
> >   deadlock.
>=20
> Hmm, this could explain a couple of weird bugs in HPL that I
> recently had...

I hope so! :)

Simon