omp_unset_lock(svar)

Purpose

This subroutine causes the executing thread to release ownership of the specified lock. The lock can then be set by another thread as required. The behavior of the omp_unset_lock subroutine is undefined if either of the following conditions occur:

Class

Subroutine.

Argument Type and Attributes

svar
Integer of kind omp_lock_kind.

Result Type and Attributes

None.

Result Value

None.

Examples

      USE omp_lib
      INTEGER A(100)
      INTEGER(kind=omp_lock_kind) LCK_X
      CALL omp_init_lock (LCK_X)
!$OMP PARALLEL PRIVATE (I), SHARED (A, X)
!$OMP DO
      DO I = 3, 100
        A(I) = I * 10
        CALL omp_set_lock (LCK_X)
        X = X + A(I)
        CALL omp_unset_lock (LCK_X)
      END DO
!$OMP END DO
!$OMP END PARALLEL
      CALL omp_destroy_lock (LCK_X)

In this example, the lock variable LCK_X is used to avoid race conditions when updating the shared variable X. By setting the lock before each update to X and unsetting it after the update, you ensure that only one thread is updating X at a given time. IBM Copyright 2003