Put differently: - You have an array of N requests - If you're only filling up M of them (where N<M) - And then you pass the whole array of size N to MPI - Then N-M of them will have garbage values (unless you initialize them to MPI_REQUEST_NULL) - And MPI's behavior with garbage values will be unpredictable / undefined
You can either pass M (i.e., the number of requests that you have *actually* filled) to MPI, or you can ensure that the N-M unused requests in the array are filled with MPI_REQUEST_NULL (which MPI_WAITANY and friends will safely ignore). One way of doing the latter is initializing the entire array with MPI_REQUEST_NULL and then only filling in the M entries with real requests. It seems much simpler / faster to just pass in M to MPI_WAITANY (any friends), not N. > On Sep 30, 2015, at 3:43 AM, Diego Avesani <diego.aves...@gmail.com> wrote: > > Dear Gilles, Dear All, > > What do you mean that the array of requests has to be initialize via > MPI_Isend or MPI_Irecv? > > In my code I use three times MPI_Isend and MPI_Irecv so I have a > send_request(3). According to this, do I have to use MPI_REQUEST_NULL? > > In the meantime I check my code > > Thanks > > Diego > > > On 29 September 2015 at 16:33, Gilles Gouaillardet > <gilles.gouaillar...@gmail.com> wrote: > Diego, > > if you invoke MPI_Waitall on three requests, and some of them have not been > initialized > (manually, or via MPI_Isend or MPI_Irecv), then the behavior of your program > is undetermined. > > if you want to use array of requests (because it make the program simple) but > you know not all of them are actually used, then you have to initialize them > with MPI_REQUEST_NULL > (it might be zero on ompi, but you cannot take this for granted) > > Cheers, > > Gilles > > > On Tuesday, September 29, 2015, Diego Avesani <diego.aves...@gmail.com> wrote: > dear Jeff, dear all, > I have notice that if I initialize the variables, I do not have the error > anymore: > ! > ALLOCATE(SEND_REQUEST(nMsg),RECV_REQUEST(nMsg)) > SEND_REQUEST=0 > RECV_REQUEST=0 > ! > > Could you please explain me why? > Thanks > > > Diego > > > On 29 September 2015 at 16:08, Diego Avesani <diego.aves...@gmail.com> wrote: > Dear Jeff, Dear all, > the code is very long, here something. I hope that this could help. > > What do you think? > > SUBROUTINE MATOPQN > USE VARS_COMMON,ONLY:COMM_CART,send_messageR,recv_messageL,nMsg > USE MPI > INTEGER :: send_request(nMsg), recv_request(nMsg) > INTEGER :: > send_status_list(MPI_STATUS_SIZE,nMsg),recv_status_list(MPI_STATUS_SIZE,nMsg) > > !send message to right CPU > IF(MPIdata%rank.NE.MPIdata%nCPU-1)THEN > MsgLength = MPIdata%jmaxN > DO icount=1,MPIdata%jmaxN > iNode = MPIdata%nodeList2right(icount) > send_messageR(icount) = RIS_2(iNode) > ENDDO > > CALL MPI_ISEND(send_messageR, MsgLength, MPI_DOUBLE_COMPLEX, > MPIdata%rank+1, MPIdata%rank+1, MPI_COMM_WORLD, send_request(MPIdata%rank+1), > MPIdata%iErr) > > ENDIF > ! > > > !recive message FROM left CPU > IF(MPIdata%rank.NE.0)THEN > MsgLength = MPIdata%jmaxN > > CALL MPI_IRECV(recv_messageL, MsgLength, MPI_DOUBLE_COMPLEX, > MPIdata%rank-1, MPIdata%rank, MPI_COMM_WORLD, recv_request(MPIdata%rank), > MPIdata%iErr) > > write(*,*) MPIdata%rank-1 > ENDIF > ! > ! > CALL MPI_WAITALL(nMsg,send_request,send_status_list,MPIdata%iErr) > CALL MPI_WAITALL(nMsg,recv_request,recv_status_list,MPIdata%iErr) > > Diego > > > On 29 September 2015 at 00:15, Jeff Squyres (jsquyres) <jsquy...@cisco.com> > wrote: > Can you send a small reproducer program? > > > On Sep 28, 2015, at 4:45 PM, Diego Avesani <diego.aves...@gmail.com> wrote: > > > > Dear all, > > > > I have to use a send_request in a MPI_WAITALL. > > Here the strange things: > > > > If I use at the begging of the SUBROUTINE: > > > > INTEGER :: send_request(3), recv_request(3) > > > > I have no problem, but if I use > > > > USE COMONVARS,ONLY : nMsg > > with nMsg=3 > > > > and after that I declare > > > > INTEGER :: send_request(nMsg), recv_request(nMsg), I get the following > > error: > > > > [Lap] *** An error occurred in MPI_Waitall > > [Lap] *** reported by process [139726485585921,0] > > [Lap] *** on communicator MPI_COMM_WORLD > > [Lap] *** MPI_ERR_REQUEST: invalid request > > [Lap] *** MPI_ERRORS_ARE_FATAL (processes in this communicator will now > > abort, > > [Lap] *** and potentially your MPI job) > > forrtl: error (78): process killed (SIGTERM) > > > > Someone could please explain to me where I am wrong? > > > > Thanks > > > > Diego > > > > _______________________________________________ > > users mailing list > > us...@open-mpi.org > > Subscription: http://www.open-mpi.org/mailman/listinfo.cgi/users > > Link to this post: > > http://www.open-mpi.org/community/lists/users/2015/09/27703.php > > > -- > Jeff Squyres > jsquy...@cisco.com > For corporate legal information go to: > http://www.cisco.com/web/about/doing_business/legal/cri/ > > _______________________________________________ > users mailing list > us...@open-mpi.org > Subscription: http://www.open-mpi.org/mailman/listinfo.cgi/users > Link to this post: > http://www.open-mpi.org/community/lists/users/2015/09/27704.php > > > > _______________________________________________ > users mailing list > us...@open-mpi.org > Subscription: http://www.open-mpi.org/mailman/listinfo.cgi/users > Link to this post: > http://www.open-mpi.org/community/lists/users/2015/09/27710.php > > _______________________________________________ > users mailing list > us...@open-mpi.org > Subscription: http://www.open-mpi.org/mailman/listinfo.cgi/users > Link to this post: > http://www.open-mpi.org/community/lists/users/2015/09/27721.php -- Jeff Squyres jsquy...@cisco.com For corporate legal information go to: http://www.cisco.com/web/about/doing_business/legal/cri/
