[MPICH] MPICH2 Thread-safety

[Rajeev Thakur]

What happens if you just configure with --enable-threads?

Rajeev 

> -----Original Message-----
> From: Sylvain Jeaugey [mailto:sylvain.jeaugey at bull.net] 
> Sent: Friday, June 09, 2006 9:10 AM
> To: Rajeev Thakur
> Cc: 'Sylvain Jeaugey'; mpich-discuss at mcs.anl.gov
> Subject: RE: [MPICH] MPICH2 Thread-safety
> 
> On Fri, 9 Jun 2006, Rajeev Thakur wrote:
> 
> > Sylvain,
> >        A lot of things are happening thread-safety-wise in 
> MPICH2. 1.0.4
> > will have much better support.
> Good to hear !
> > Nonetheless, the paragraph you quote will
> > work in 1.0.3 as well because the lock is released 
> somewhere inside the
> > progress engine before a receive blocks. (It's not obvious 
> from looking at
> > the code for MPI_Recv.)
> Ok. Good.
> 
> > What exactly doesn't work for you? We have fixed a
> > couple of bugs that were found.
> It doesn't compile with
> ./configure --enable-threads=multiple:global_mutex
> typing 'make' after configure gives :
> In file included from ../../../../include/mpiimpl.h:83,
>                   from sock.c:9:
> ../../../../include/mpiimplthread.h:10:49: syntax error ':' 
> without preceding '?'
> ... and a lot of other errors after that.
> 
> > Another fix that is coming is that you won't need to build 
> MPICH2 separately
> > to get a thread safe version. Support for thread safety 
> will be there by
> > default and will be enabled when the user selects it with 
> MPI_Init_thread.
> > If the user doesn't call MPI_Init_thread, the code will not 
> use any thread
> > locks, so there is no penalty.
> That's a very, very good thing ! I'm eager to have this new version !
> 
> Thanks for your help,
> 
> Sylvain
> 
> >> -----Original Message-----
> >> From: owner-mpich-discuss at mcs.anl.gov
> >> [mailto:owner-mpich-discuss at mcs.anl.gov] On Behalf Of 
> Sylvain Jeaugey
> >> Sent: Friday, June 09, 2006 7:04 AM
> >> To: mpich-discuss at mcs.anl.gov
> >> Subject: [MPICH] MPICH2 Thread-safety
> >>
> >> Hi all,
> >>
> >> After some tries, it looks like MPICH2 is still a little far
> >> from being
> >> thread-safe.
> >>
> >> Nothing seems to be currently done in this direction, so I'm
> >> posting here
> >> to know what I could do to improve this.
> >>
> >> The only thread policy is "global_mutex", which -in my view-
> >> contradicts
> >> Section 8.7.1 of the standard :
> >>
> >> "Example Process 0 consists of two threads. The first thread
> >> executes a
> >> blocking send call MPI_Send(buff1, count, type, 0, 0, comm),
> >> whereas the
> >> second thread executes a blocking receive call 
> MPI_Recv(buff2, count,
> >> type, 0, 0, comm, &status). I.e., the first thread sends a
> >> message that is
> >> received by the second thread. This communication should
> >> always succeed."
> >>
> >> There is a lot of code for "thread-safety". Still, I can't
> >> get something
> >> working.
> >> Is there a chance that things will be better in 1.0.4 ? Where
> >> should I
> >> begin if I want to improve things (and not destroy what's 
> already be
> >> done) ?
> >>
> >> Thanks in advance,
> >>
> >> Sylvain
> >>
> >>
> >
> >
> 
>