Root TThread Multi-thread example

조금 더 빠른 졸업을 위해

#include <TThreadExecutor.h>
#include <iostream>
 
const UInt_t poolSize = 4U;
Int_t mtbb201_parallelHistoFill()
{
   ROOT::EnableThreadSafety();
   TH1::AddDirectory(false);
   ROOT::TThreadExecutor pool(poolSize);
   auto fillRandomHisto = [](int seed = 0) {
      TRandom3 rndm(seed);
      auto h = new TH1F("myHist", "Filled in parallel", 128, -8, 8);
      for (auto i : ROOT::TSeqI(1000000)) {
         h->Fill(rndm.Gaus(0, 1));
      }
      return h;
   };
   auto seeds = ROOT::TSeqI(23);
   ROOT::ExecutorUtils::ReduceObjects<TH1F *> redfunc;
   auto sumRandomHisto = pool.MapReduce(fillRandomHisto, seeds, redfunc);
   auto c = new TCanvas();
   sumRandomHisto->Draw();
   return 0;
}

#include <iostream>
 
using namespace std;
 
// The number of workers
const UInt_t nWorkers = 10U;
 
Int_t main() {
   auto workItem = [](UInt_t workerID) {
      for (int i = workerID; i < 1111; i += nWorkers) {
        cout<<"worker["<<workerID<<"] : "<< i<<endl;
      }
   }
   // Create the pool of workers
  ROOT::TProcessExecutor workers(nWorkers);
 
  // Fill the pool with work
  workers.Map(workItem, ROOT::TSeqI(nWorkers));
 
  FILE *fk = fopen("KILLME","r");
  if(fk){
      printf("KILLME file exist Bye \n");
      gSystem->Exec("rm -f KILLME");
  }
 
  return 0;
}

#include <iostream>
using namespace std;
 
Int_t main() {
   // Total amount of numbers
   const UInt_t nNumbers = 20000000U;
   // The number of workers
   const UInt_t nWorkers = 4U;
   
   // We define our work item
   auto workItem = [](UInt_t workerID) {
      // One generator, file and ntuple per worker
      TRandom3 workerRndm(workerID); // Change the seed
      TFile f(Form("myFile_%u.root", workerID), "RECREATE");
      TH1F h(Form("myHisto_%u", workerID), "The Histogram", 64, -4, 4);
      for (UInt_t i = 0; i < nNumbers; ++i) {
         h.Fill(workerRndm.Gaus());
      }
      h.Write();
      return 0;
   };
 
   // Create the pool of workers
   ROOT::TProcessExecutor workers(nWorkers);
   // Fill the pool with work
   workers.Map(workItem, ROOT::TSeqI(nWorkers));
}