!.. 1. sections指令在大多数情况下与一个独立的parallel指令一起使用,因此openmp提供了一个指令!$parallel sections来方便编程人员编程
!.. 2. 一个程序中可以定义多个sections结构,每个sections结构中又可以定义多个section
!.. 3. 同一个sections中section之间处于并行状态,sections与其他sections之间处于串行状态
!.. 4. section内部不允许出现能够到达section之外的跳转语句,也不允许有外部的跳转语句到达section内部
Program multi_sections
use omp_lib
implicit none
integer :: tid, nthreads
call omp_set_num_threads(6)
write(*,'(1x,a)') "Section No. section no. nthreads id"
write(*,'(1x,a)') "Sections A "
!$omp parallel private(tid, nthreads)
!$omp sections
!$omp section
tid = omp_get_thread_num()
nthreads = omp_get_num_threads()
write(*,'(1x,a,i8,i8)') " section 1: ", nthreads, tid
!$omp section
tid = omp_get_thread_num()
nthreads = omp_get_num_threads()
write(*,'(1x,a,i8,i8)') " section 2: ", nthreads, tid
!$omp section
tid = omp_get_thread_num()
nthreads = omp_get_num_threads()
write(*,'(1x,a,i8,i8)') " section 3: ", nthreads, tid
!$omp end sections
!$omp end parallel
write(*,'(1x,a)') "Sections B "
!$omp parallel private(tid, nthreads)
!$omp sections
!$omp section
tid = omp_get_thread_num()
nthreads = omp_get_num_threads()
write(*,'(1x,a,i8,i8)') " section 4: ", nthreads, tid
!$omp section
tid = omp_get_thread_num()
nthreads = omp_get_num_threads()
write(*,'(1x,a,i8,i8)') " section 5: ", nthreads, tid
!$omp section
tid = omp_get_thread_num()
nthreads = omp_get_num_threads()
write(*,'(1x,a,i8,i8)') " section 6: ", nthreads, tid
!$omp end sections
!$omp end parallel
End program multi_sections
!.. 总结
!.. 1. 程序定义了两个sections并行域。每个sections并行域有三个section,sections并行域中执行section的三个子进程号各不相同
!.. 2. sections A与sections B的并行域在程序中处于串行状态
Fortran:openmp笔记18
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