2402-pcluster-threads

multithread_01.cpp

#include <chrono>
#include <iostream>
#include <thread>
#include <unistd.h>
#include <vector>

void whoami(int i) {
  int sleep_ms = rand() % 5000;

  std::thread::id this_id = std::this_thread::get_id();
  std::cout << "Thread " << i << ": " << this_id << " hello" << std::endl;
  std::this_thread::sleep_for(std::chrono::milliseconds(sleep_ms));
  std::cout << "Thread " << i << ": " << this_id << " goodbye" << std::endl;
}

int getThreads(void) {
  const auto processor_count = std::thread::hardware_concurrency();
  std::cout << processor_count << " threads available" << std::endl;
  return processor_count;
}

float getMemory() {
  long pages = sysconf(_SC_PHYS_PAGES);
  long page_size = sysconf(_SC_PAGE_SIZE);
  float system_memory_gib = (pages * page_size) / std::pow(1024, 3);
  std::cout << "System memory GiB: " << std::setprecision(3) << system_memory_gib << std::endl;
  return system_memory_gib;
}

int main(int argc, char const *argv[]) {
  int nthreads;
  std::vector<std::thread> threads = {};

  getMemory();
  nthreads = getThreads();

  for (int i = 0; i < nthreads; i++) {
    threads.push_back(std::thread(whoami, i));
  }

  for (int i = 0; i < nthreads; i++) {
    threads[i].join();
  }

  return 0;
}

param_boot.sh

#!/bin/bash
#SBATCH --job-name="param_boot_r5a-2xl"
#SBATCH --ntasks=1
#SBATCH --time=96:00:00
#SBATCH --cpus-per-task=8
#SBATCH --ntasks-per-node=1
#SBATCH --exclusive
#SBATCH --output="param_boot_%A_%a.log"
#SBATCH --error="param_boot_%A_%a.err"
#SBATCH --array=[1-10]
#SBATCH --partition=r5a-2xl

mpirun ./multithread_01