m_delay_file_access.f90

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!>
!! @file
!! @brief Contains module m_delay_file_access
 
!> @brief Rank-staggered file access delays to prevent I/O contention on parallel file systems
module m_delay_file_access
 
    use m_precision_select
 
    implicit none
 
    private
 
    public :: s_delay_file_access
 
    integer, private, parameter :: n_processes_file_access = 128, file_access_delay_unit = 10000
 
contains
 
    !> Introduce a rank-dependent busy-wait delay to stagger parallel file access and reduce I/O contention.
    impure subroutine s_delay_file_access(process_rank)
 
        integer, intent(in) :: process_rank
        integer             :: i, n_file_access_delay_iterations
        real(wp)            :: num, dummy
 
        n_file_access_delay_iterations = (process_rank/n_processes_file_access)*file_access_delay_unit
 
        do i = 1, n_file_access_delay_iterations
            call random_number(num)
            dummy = num*num
        end do
 
    end subroutine s_delay_file_access
 
end module m_delay_file_access