Concurrent Quick Sort Class in OpenMP

Q: Design a class for concurrent quicksort in C++.

Decided to use OpenMp since Pthread doesn't work well with classes, not without ton's of efforts.

Code

#include <iostream> #include <vector> #include <omp.h> #include <sched.h> using namespace std; void swap(int& a, int& b) { int temp = a; a = b; b = temp; } class qs {  private: vector<int> nos;  public: qs(std::vector<int> input) { nos = vector<int>(input); } void disp() { for (int i = 0; i < nos.size(); i++) { cout << nos[i] << "\t"; } cout << endl; } int partition(int l, int h) { int key = nos[l]; int i = l + 1; int j = l; while (i <= h) { if (nos[i] < key) { j++; swap(nos[i], nos[j]); } i++; } swap(nos[j], nos[l]); return j; } void sort() { this->sort(0, nos.size() - 1); } void sort(int low, int high) { if (low >= high) return; int mid = partition(low, high); omp_set_nested(1); // to allow nested threads #pragma omp parallel sections { #pragma omp section { sort(low, mid - 1); cout << "Thread id " << omp_get_thread_num() << " core " << sched_getcpu() << endl; } #pragma omp section { sort(mid + 1, high); cout << "Thread id " << omp_get_thread_num() << " core " << sched_getcpu() << endl; } } } }; int main() { cout << "Program for quicksort" << endl; vector<int> input; cout << "Enter the number of elements" << endl; int num; cin >> num; while (num--) { int temp; cin >> temp; input.push_back(temp); } qs arr = qs(input); cout << "Array before sorting \n"; arr.disp(); cout << "Array after sorting\n"; arr.sort(); arr.disp(); return 0; }

Compilation

• g++ filename.cpp -fopenmp