Thx a lot. I will be more careful with declaration of the MPI variables.
Pawel J.
W dniu 2016-01-22 o 16:06, Nick Papior pisze:
The status field should be
integer :: stat(MPI_STATUS_SIZE)
Perhaps n is located stackwise just after the stat variable, which
then overwrites it.
2016-01-22 15:37 GMT+01:00 Paweł Jarzębski <pj...@ippt.pan.pl
<mailto:pj...@ippt.pan.pl>>:
Hi,
I wrote this code:
program hello
implicit none
include 'mpif.h'
integer :: rank, dest, source, tag, ierr, stat
integer :: n
integer :: taskinfo, ptr
call MPI_INIT(ierr)
call MPI_COMM_RANK(MPI_COMM_WORLD, rank, ierr)
if(rank.eq.0) then
write(*,*) 'Hello'
n = 20
dest = 1
tag = 1
taskinfo = n
call MPI_SEND(taskinfo, 1, MPI_INTEGER, dest, tag,
1 MPI_COMM_WORLD, ierr)
tag = tag + 1
call MPI_SEND(ptr, 1, MPI_INTEGER, dest, tag,
1 MPI_COMM_WORLD, ierr)
else
source = 0
tag = 1
! n = 1
call MPI_RECV(taskinfo, 1, MPI_INTEGER, source, tag,
1 MPI_COMM_WORLD, stat, ierr)
n = taskinfo
tag = tag + 1
write(*,*) 'n1 ', n
write(*,*) 'taskinfo1 ', taskinfo
call MPI_RECV(ptr, 1, MPI_INTEGER, source, tag,
1 MPI_COMM_WORLD, stat, ierr)
write(*,*) 'n2 ', n
write(*,*) 'taskinfo2 ', taskinfo
endif
call MPI_FINALIZE(ierr)
end
I supposed that it should produce this:
Hello
n1 20
taskinfo1 20
n2 20
taskinfo2 20
But in fact it produces this:
Hello
n1 20
taskinfo1 20
n2 2
taskinfo2 20
It's strange to me that variable "n" is changed after call to MPI
subroutine, but I dont even put it in calls to MPI.
If I comment line 13 with " write(*,*) 'Hello' " everything is ok.
If I uncomment line 30 with "n = 1", everything is ok as well.
Could anybody explain me what is happening?
I tested it on:
1) intel fortran compiler 14.0 and openmpi 1.6.5
1) intel fortran compiler 13.1.3 and openmpi 1.8.4
Best regards,
Pawel J.
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--
Kind regards Nick
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