OpenMP Implementation of a Team of AD Threads

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team_openmp.cpp

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@(@\newcommand{\W}[1]{ \; #1 \; } \newcommand{\R}[1]{ {\rm #1} } \newcommand{\B}[1]{ {\bf #1} } \newcommand{\D}[2]{ \frac{\partial #1}{\partial #2} } \newcommand{\DD}[3]{ \frac{\partial^2 #1}{\partial #2 \partial #3} } \newcommand{\Dpow}[2]{ \frac{\partial^{#1}}{\partial {#2}^{#1}} } \newcommand{\dpow}[2]{ \frac{ {\rm d}^{#1}}{{\rm d}\, {#2}^{#1}} }@)@This is cppad-20221105 documentation. Here is a link to its current documentation . OpenMP Implementation of a Team of AD Threads See team_thread.hpp for this routines specifications.

# include <omp.h>
# include <cppad/cppad.hpp>
# include "../team_thread.hpp"

namespace {
    using CppAD::thread_alloc;

    // number of threads in this team
    size_t num_threads_;

    // used to inform CppAD when we are in parallel execution mode
    bool in_parallel(void)
    {   return omp_in_parallel() != 0; }

    // used to inform CppAD of the current thread number
    size_t thread_num(void)
    {   return static_cast<size_t>( omp_get_thread_num() ); }
}

bool team_create(size_t num_threads)
{
    bool ok = ! in_parallel();
    ok     &= thread_num() == 0;;
    ok     &= num_threads > 0;

    // Turn off dynamic thread adjustment
    omp_set_dynamic(0);

    // Set the number of OpenMP threads
    omp_set_num_threads( int(num_threads) );

    // setup for using CppAD::AD<double> in parallel
    thread_alloc::parallel_setup(num_threads, in_parallel, thread_num);
    thread_alloc::hold_memory(true);
    CppAD::parallel_ad<double>();

    // inform team_work of number of threads
    num_threads_ = num_threads;

    return ok;
}

bool team_work(void worker(void))
{   bool ok = ! in_parallel();
    ok     &= thread_num() == 0;;
    ok     &= num_threads_ > 0;

    int number_threads = int(num_threads_);
    int thread_num;
# pragma omp parallel for
    for(thread_num = 0; thread_num < number_threads; thread_num++)
        worker();
// end omp parallel for

    return ok;
}

bool team_destroy(void)
{   bool ok = ! in_parallel();
    ok     &= thread_num() == 0;;
    ok     &= num_threads_ > 0;

    // inform team_work of number of threads
    num_threads_ = 1;

    // Set the number of OpenMP threads to one
    omp_set_num_threads( int(num_threads_) );

    // inform CppAD no longer in multi-threading mode
    thread_alloc::parallel_setup(num_threads_, nullptr, nullptr);
    thread_alloc::hold_memory(false);
    CppAD::parallel_ad<double>();

    return ok;
}

const char* team_name(void)
{   return "openmp"; }

Input File: example/multi_thread/openmp/team_openmp.cpp