catching a deadlock in a simple odd-even sending

Posted by user562264 on Stack Overflow See other posts from Stack Overflow or by user562264
Published on 2011-01-04T08:50:52Z Indexed on 2011/01/04 8:53 UTC
Read the original article Hit count: 525

Filed under:

fortran

|

mpi

|

fortran90

I'm trying to solve a simple problem with MPI, my implementation is MPICH2 and my code is in fortran. I have used the blocking send and receive, the idea is so simple but when I run it it crashes!!! I have absolutely no idea what is wrong? can anyone make quote on this issue please? there is a piece of the code:

integer,parameter::IM=100,JM=100

REAL,ALLOCATABLE ::T(:,:),TF(:,:)

CALL MPI_COMM_RANK(MPI_COMM_WORLD,RNK,IERR)

CALL MPI_COMM_SIZE(MPI_COMM_WORLD,SIZ,IERR)

prv = rnk-1

nxt = rnk+1

LIM = INT(IM/SIZ)

IF (rnk==0) THEN

ALLOCATE(TF(IM,JM))

prv = MPI_PROC_NULL

ELSEIF(rnk==siz-1) THEN

NXT = MPI_PROC_NULL

LIM = LIM+MOD(IM,SIZ)

END IF

IF (MOD(RNK,2)==0) THEN

CALL MPI_SEND(T(2,:),JM+2,MPI_REAL,PRV,10,MPI_COMM_WORLD,IERR)

CALL MPI_RECV(T(1,:),JM+2,MPI_REAL,PRV,20,MPI_COMM_WORLD,STAT,IERR)

ELSE

CALL MPI_RECV(T(LIM+2,:),JM+2,MPI_REAL,NXT,10,MPI_COMM_WORLD,STAT,IERR)

CALL MPI_SEND(T(LIM+1,:),JM+2,MPI_REAL,NXT,20,MPI_COMM_WORLD,IERR)

END IF

as I understood even processes are not receiving anything while the odd ones finish sending successfully, in some cases when I added some print to observe what is going on I saw that the variable NXT is changing during the sending procedure!!! for example all the odd process was sending message to process 0 not their next one!

© Stack Overflow or respective owner

Related posts about fortran

passing a fortran int array to C++ by calling C++ function in fortran

as seen on Stack Overflow - Search for 'Stack Overflow'
hi, I am trying to call a C++ function in FORTRAN subroutine. This C+ function is supposed to update an integer array. Here is a non-working code I wrote. Can someone please let me know what the issue is: ! FORTRAN function that calls a C++ function subroutine my_function() integer(4) ar(*) … >>> More
MinGW/G++/g95 link problem - libf95 undefined reference to `MAIN_'

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi folks, Summing up, my problem consists on compiling g95 objects inside a C++ application. Actually, I'm constructing an interface for an old fortran program. For this task, I'm using the wxWidgets GUI library, and calling fortran subroutines when necessary. At the beginning, I was developing the… >>> More
Fortran arrays and subroutines

as seen on Stack Overflow - Search for 'Stack Overflow'
I'm going through a Fortran code, and one bit has me a little puzzled. There is a subroutine, say SUBROUTINE SSUB(X,...) REAL*8 X(0:N1,1:N2,0:N3-1),... ... RETURN END Which is called in another subroutine by: CALL SSUB(W(0,1,0,1),...) where W is a 'working array'. It appears that a specific… >>> More
fortran 90 user defined type, passing by value ?

as seen on Stack Overflow - Search for 'Stack Overflow'
I have an issue in fortran 90. I have a user defined type and when I call one of the MPI subroutines the data looks to be passed by values (not address, as I thought it should). The output arguments aren't modified. It seems to be specific to the MPI calls I tried the same thing in a simple test… >>> More
Should External Routine Be Declared Always in Fortran?

as seen on Stack Overflow - Search for 'Stack Overflow'
In my fortran code I made the following call to dnrm2 routine d = dnrm2(n, ax, 1) Just a simple call that would return me a double precision result. The problem is whether I should declare the function at the start of my script. I found that if I don't declare it, and when I compile the code in… >>> More

Related posts about mpi

Message Passing Interface (MPI)

as seen on Daniel Moth - Search for 'Daniel Moth'
So you have installed your cluster and you are done with introductory material on Windows HPC. Now you want to develop an application with the most common programming model: Message Passing Interface.The MPI programming model is a standard with implementations from many vendors. For newbies (like… >>> More
How do I debug an MPI program?

as seen on Stack Overflow - Search for 'Stack Overflow'
I have an MPI program which compiles and runs, but I would like to step through it to make sure nothing bizarre is happening. Ideally, I would like a simple way to attach GDB to any particular process, but I'm not really sure whether that's possible or how to do it. An alternative would be having… >>> More
trying to build Boost MPI, but the lib files are not created. What's going on?

as seen on Stack Overflow - Search for 'Stack Overflow'
I am trying to run a program with Boost MPI, but the thing is I don't have the .lib. So I try to create one by following the instruction at http://www.boost.org/doc/libs/1_43_0/doc/html/mpi/getting_started.html#mpi.config The instruction says "For many users using LAM/MPI, MPICH, or OpenMPI, configuration… >>> More
MPI: is there mpi libraries capable of message compression?

as seen on Stack Overflow - Search for 'Stack Overflow'
Sometimes MPI is used to send low-entropy data in messages. So it can be useful to try to compress messages before sending it. I know that MPI can work on very fast networks (10 Gbit/s and more), but many MPI programs are used with cheap network like 0,1G or 1Gbit/s Ethernet and with cheap (slow,… >>> More
Slides and code for MPI Cluster Debugger

as seen on Daniel Moth - Search for 'Daniel Moth'
I've blogged before about the MPI Cluster Debugger in VS2010 that facilitates launching the application on the cluster and attaching the debugger (btw, a shorter version of the screencast I link to there, is here).There have been requests for the code I use in the screencast, so please find a ZIP… >>> More