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/*!
* Copyright (c) 2014 by Contributors
* \file basic.cc
* \brief This is an example demonstrating what is Allreduce
*
* \author Tianqi Chen
*/
#define _CRT_SECURE_NO_WARNINGS
#define _CRT_SECURE_NO_DEPRECATE
#include <vector>
#include <rabit/rabit.h>
using namespace rabit;
int main(int argc, char *argv[]) {
int N = 3;
if (argc > 1) {
N = atoi(argv[1]);
}
std::vector<int> a(N);
rabit::Init(argc, argv);
for (int i = 0; i < N; ++i) {
a[i] = rabit::GetRank() + i;
}
printf("@node[%d] before-allreduce: a={%d, %d, %d}\n",
rabit::GetRank(), a[0], a[1], a[2]);
// allreduce take max of each elements in all processes
Allreduce<op::Max>(&a[0], N);
printf("@node[%d] after-allreduce-max: a={%d, %d, %d}\n",
rabit::GetRank(), a[0], a[1], a[2]);
// second allreduce that sums everything up
Allreduce<op::Sum>(&a[0], N);
printf("@node[%d] after-allreduce-sum: a={%d, %d, %d}\n",
rabit::GetRank(), a[0], a[1], a[2]);
rabit::Finalize();
return 0;
}
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