Intel® Fortran Compiler 16.0 User and Reference Guide

FLUSH Directive

OpenMP* Fortran Compiler Directive: Identifies synchronization points at which the threads in a team must provide a consistent view of memory.

!$OMP FLUSH [(list)]

list

Is the name of one or more variables to be flushed. Names must be separated by commas.

The binding thread set for a FLUSH construct is the encountering thread.

The FLUSH directive must appear at the precise point in the code at which the synchronization is required. To avoid flushing all variables, specify a list.

Thread-visible variables are written back to memory at the point at which this directive appears. Modifications to thread-visible variables are visible to all threads after this point. Subsequent reads of thread-visible variables fetch the latest copy of the data.

Thread-visible variables include the following data items:

The FLUSH directive is implied for the following directives (unless the NOWAIT keyword is used):

Example

The following example uses the FLUSH directive for point-to-point synchronization between pairs of threads:

  !$OMP PARALLEL DEFAULT(PRIVATE) SHARED(ISYNC)
        IAM = OMP_GET_THREAD_NUM( )
        ISYNC(IAM) = 0
  !$OMP BARRIER
        CALL WORK( )
  C I AM DONE WITH MY WORK, SYNCHRONIZE WITH MY NEIGHBOR
        ISYNC(IAM) = 1
  !$OMP FLUSH(ISYNC)
  C WAIT TILL NEIGHBOR IS DONE
        DO WHILE (ISYNC(NEIGH) .EQ. 0)
  !$OMP FLUSH(ISYNC)
        END DO
  !$OMP END PARALLEL

See Also