[Bug fortran/40201] New: DATE_AND_TIME returns GMT hour sometimes with OpenMP

["longb at cray dot com" <gcc-bugzilla at gcc dot gnu dot org>]

Test case:
program testhour
use omp_lib
integer :: h(1000), h1(1000), bins(0:23), v(8)

call omp_set_num_threads(4)

print *, "Running on",omp_get_max_threads(),"threads
and",omp_get_num_procs(),"procs."

!$omp parallel do schedule(STATIC,250)
do i=1,1000
   call date_and_time(values=v)
   h(i) = v(5)
end do
!$omp end parallel do

   print *, "date_and_time hour:"
   bins = 0
   do i=1,1000
      bins(h(i)) = bins(h(i)) + 1
   end do
   do i=0,23
      if (bins(i) > 0) print *, "For",bins(i),"calls, hour =",i
   end do


end program testhour

Compile with -fopenmp, and run on 4 threads:

> aprun -n1 -d4 ./dattest
 Running on           4 threads and           1 procs.
 date_and_time hour:
 For         707 calls, hour =          13
 For         293 calls, hour =          18
Application 2721423 resources: utime 0, stime 0


This was run in US Central Daylight time zone.  Most of the time, the correct
hour (13) was returned, but a sizable number of times, the hour correct for GMT
was returned instead. It looks like the conversion from GMT to the local time
zone sometimes fails when the routine is concurrently called from more that one
thread.

I wrote a similar program that called the system localtime() routine instead,
as well as localtime_r(), and both consistently returned the correct hour.

The same code compiled with either the Cray or PGI compiler consistently
returns the same hour for every iteration.


-- 
           Summary: DATE_AND_TIME returns GMT hour sometimes with OpenMP
           Product: gcc
           Version: 4.3.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: longb at cray dot com
  GCC host triplet: Linux, x86-64
GCC target triplet: Linux, x86-64 (quad-core Opteron)


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40201