Program with simple coarrays hangs

[Arjen_Markus]

Hello,

in my quest to find a solution for the problem I posted in the thread "Internal compiler error with lock/unlock", I stumbled upon another problem. Again using Intel Fortran 12.0.3.

Here is the program:

! checkscalar.f90 --

! Check some odd (erroneous) behaviour with scalar coarrays

!

program checkscalar

implicit none

logical, codimension

:: new_results

logical, codimension

:: ready

ready = .false.

new_results = .true. ! Indicates the image has results available

write(*,*) 'Image', this_image(), new_results

sync all

write(*,*) 'Image2', this_image(), new_results

!

! Collect the found primes in image 1, create new tasks

! for all images

!

do while ( .not. ready )

if ( this_image() == 1 ) then

call collect_results

endif

call sleepqq(1)

enddo

contains

!

! Subroutine to collect the results from all

! images (run by image 1)

!

subroutine collect_results

integer :: i

integer :: np

integer :: maxindex

do i = 1,num_images()

write(*,*) 'Examine', i, new_results

enddo

do i = 1,num_images()

ready = .true.

enddo

end subroutine collect_results

end program checkscalar


It does not do much: in image 1 I print the value of new_results and when the
loop is finished I set the flag ready in all images so that they will stop. At least
that is my intention.

The output of one run with this program is:

Image 6 T

Image 1 T

Image 3 T

Image2 3 T

Image 7 T

Image2 7 T

Image2 6 T

Image 5 T

Image 2 T

Image2 2 T

Image 4 T

Image 8 T

Image2 4 T

Image2 1 T

Examine 1 T

Image2 8 T

Image2 5 T

(after a few seconds of no progress at all, I stopped the program)

So, all 8 images start, image 1 is entering the loop, prints the value of new_results on that
image, and then hangs - it does not get beyond this!

Does anyone have any clues? Am I doing something wrong? (Possible, of course, but the
program is so simple that I can not believe that.)

Regards,

Arjen

[Steven_L_Intel1]

It is not that sync all is broken, but for some reason a refernece to the local variable isn't getting the updated value. Issue ID is DPD200168369.

[jimdempseyatthecove]

Quoting Steve Lionel (Intel)

It is not that sync all is broken, but for some reason a refernece to the local variable isn't getting the updated value. Issue ID is DPD200168369.

?? isn't that the purpose of sync all ??
Jim

[Steven_L_Intel1]

Well, no - it is also a barrier to continued execution until all images reach that point.

[jimdempseyatthecove]

(toung in cheek)

Then it appears that one should always use YourCoArrayVariable[yourImageNumber] instead of YourCoArrayVariable whenever some other image could write to YourCoArrayVariable (because sync all, although reportedly not broken, does not update local image of YourCoArrayVariable).

(toung back where it belongs)

There may be a race condition in an optimization whereby you omit poling other processes if you "know" no updates to your shared variable(s) were made. (error in code relating to condition variables on Linux). Might be a place to look after you get a reproducer.

Jim Dempsey

[Steven_L_Intel1]

The problem in the initial post got fixed somewhere along the way - it works now in the current compiler, Composer XE 2011 Update 11.