Parallel Programming in Fortran 95 using OpenMP - People

62 4. The OpenMP run-time library
The OMP test lock function returns .TRUE. if the simple lock associated with svar is
successfully set; otherwise it returns .FALSE..
The OMP test nest lock function returns the new value of the nesting counter if the
nestable lock associated with nvar is successfully set; otherwise it returns zero.
4.2.5 OMP destroy lock and OMP destroy nest lock
Once a lock is no longer needed, it is necessary to uninitialize the corresponding lock
variable. The present subroutines are meant for that. Their interface declarations are:
subroutine OMP_destroy_lock(svar)
integer(kind = OMP_lock_kind), intent(inout) :: svar
end subroutine OMP_destroy_lock
subroutine OMP_destroy_nest_lock(nvar)
integer(kind = OMP_nest_lock_kind), intent(inout) :: nvar
end subroutine OMP_destroy_nest_lock
4.2.6 Examples
To show the use of these subroutines and functions, the following example is given:
program Main
use omp_lib
implicit none
integer(kind = OMP_lock_kind) :: lck
integer(kind = OMP_integer_kind) :: ID
call OMP_init_lock(lck)
!$OMP PARALLEL SHARED(LCK) PRIVATE(ID)
ID = OMP_get_thread_num()
call OMP_set_lock(lck)
write(*,*) "My thread is ", ID
call OMP_unset_lock(lck)
!$OMP END PARALLEL
call OMP_destroy_lock(lck)
end program Main
In this example the first thing done, is the association of the lock variable lck with
a simple lock, using OMP init lock. Once inside the parallel region, the threads ask for
the ownership of the lock lck with the aid of a call to OMP set lock. Thewrite to screen
command following this call is only executed by the thread which owns the lock. Once
the work is done, the lock is released with the call to OMP unset lock so that another