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OpenMP Home PageSECTIONS Directive
The SECTIONS directive specifies that code in the the enclosed SECTION blocks are to be divided among the threads in the team. Each section is executed once.
!$OMP SECTIONS [clause[[,]clause ...] [!$OMP SECTION] code block [!$OMP SECTION code block] ... !$OMP END SECTIONS [NOWAIT]
The clause can be one of the following:
- PRIVATE (list)
- FIRSTPRIVATE (list)
- LASTPRIVATE (list)
- REDUCTION ({operator | intrinsic):list)
- See operator and intrinsic list for Parallel Regions.
Example
!Filename: sections.f90
!
!This shows code that is executed
!in sections.
PROGRAM SECTIONS
IMPLICIT NONE
INTEGER OMP_GET_THREAD_NUM, tnumber
!$OMP PARALLEL
!$OMP SECTIONS PRIVATE(tnumber)
!$OMP SECTION
tnumber=OMP_GET_THREAD_NUM()
PRINT *,"This is section 1 being executed by thread",tnumber
!$OMP SECTION
tnumber=OMP_GET_THREAD_NUM()
PRINT *,"This is section 2 being executed by thread",tnumber
!$OMP SECTION
tnumber=OMP_GET_THREAD_NUM()
PRINT *,"This is section 3 being executed by thread",tnumber
!$OMP SECTION
tnumber=OMP_GET_THREAD_NUM()
PRINT *,"This is section 4 being executed by thread",tnumber
!$OMP END SECTIONS
!$OMP END PARALLEL
END PROGRAM SECTIONS
Compiling and running on franklin:
> cat sections.pbs
#PBS -N sections
#PBS -j oe
#PBS -o sections.out
#PBS -q interactive
#PBS -S /bin/bash
#PBS -l mppwidth=1
#PBS -l mppnppn=1
#PBS -l mppdepth=2
#PBS -l walltime=00:05:00
#PBS -V
cd $PBS_O_WORKDIR
ftn -o sections -mp=nonuma -Minfo=mp sections.f90
export OMP_NUM_THREADS=2
aprun -n 1 -N 1 ./sections
> qsub sections.pbs
500738.nid00003
> cat sections.out
/opt/xt-pe/2.0.44a2/bin/snos64/ftn: INFO: linux target is being used
sections.f90:
sections:
11, Parallel region activated
12, Begin sections
17, New section
20, New section
23, New section
26, End sections
Parallel region terminated
This is section 2 being executed by thread 1
This is section 4 being executed by thread 1
This is section 1 being executed by thread 0
This is section 3 being executed by thread 0
Application 4734431 resources: utime 0, stime 0
