Optimizing existing code to work faster

ROOT
1

Hi guys!

I have a code with name CompareHitsToPatterns, which basically reads in two files
“HitWords_tower0_SSW16.root” and “CollectedPatterns_tower0_SSW16_0.root”. Inside HitWords is a leaf called “HitWords” and inside Patterns is a leaf “patternHitwords”. The idea is that this code match hitwords to patterns hitwords and yielding true or false. The problem is that this program works really slow! The code is

#include "../Source/Timer.h"
#include "TFile.h"
#include "TTree.h"
#include "TH1.h"
#include "TROOT.h"
#include <TEfficiency.h>


void CompareHitsToPatterns(){
  TFile    PatternFile("out/CollectedPatterns/CollectedPatterns_tower0_SSW16_0.root");
  TTree  * PatternTree = (TTree*) PatternFile.Get("patternTree");

  
  TFile    HitFile("out/CollectedHits/HitWords_tower0_SSW16.root");
  TTree  * HitTree = (TTree*) HitFile.Get("HitWords");
  
  // Preparing the containers to be filled with data from the tree:
  Long64_t HitWord  = 0;
  Int_t HitLayer = 0;
  Int_t EventNumber = 0;
  Long64_t PatternHitWords[15] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};

  Double_t trackPt = 0;
  Double_t truthPt = 0;

  TH1F * matchedPt = new TH1F("matchedPt","p_{T} of matched patterns;p_{T} [GeV];n;",30,0,30);
  TEfficiency* PtEff = new TEfficiency("eff","my eff;trackPt;#epsilon",600,0,10);

  // Linking the local variables to the tree branches
  HitTree->SetBranchAddress("HitWord", &HitWord);
  HitTree->SetBranchAddress("HitLayer", &HitLayer);
  HitTree->SetBranchAddress("EventNumber", &EventNumber);
  HitTree->SetBranchAddress("trackPt", &trackPt);
  HitTree->SetBranchAddress("truthPt", &truthPt);

  PatternTree->SetBranchAddress("HitWord_5", &PatternHitWords[5]);
  PatternTree->SetBranchAddress("HitWord_7", &PatternHitWords[7]);
  PatternTree->SetBranchAddress("HitWord_9", &PatternHitWords[9]);
  PatternTree->SetBranchAddress("HitWord_10", &PatternHitWords[10]);
  PatternTree->SetBranchAddress("HitWord_11", &PatternHitWords[11]);
  PatternTree->SetBranchAddress("HitWord_12", &PatternHitWords[12]);
  PatternTree->SetBranchAddress("HitWord_13", &PatternHitWords[13]);
  PatternTree->SetBranchAddress("HitWord_14", &PatternHitWords[14]);

  // Create a way to see if the pattern was matched

  Int_t nMatchedPatterns = 0;
  
  Long64_t nEntriesPatternTree = PatternTree->GetEntries();
  Long64_t nEntriesHitTree = HitTree->GetEntries();

  HitTree ->  GetEntry(nEntriesHitTree-1);
  Int_t eventMax = EventNumber;
  cout << "maximum eventnr: " << eventMax << "\n"; 
  
  for(Int_t event = 0; event < eventMax; event++){

    for (Long64_t iPattern = 0; iPattern < nEntriesPatternTree; iPattern++) {

      PatternTree->GetEntry(iPattern);

      Bool_t MatchedHits[15] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
      
      for(Long64_t iHit = 0; iHit < nEntriesHitTree; iHit++){

	HitTree->GetEntry(iHit);
	
  	if( EventNumber < event) continue;
  	if( EventNumber > event) break;
    
	// std::cout << "Comparing patterHitWord " << PatternHitWords[HitLayer] << " to ";
	// std::cout << " hit " << HitWord << endl;
	
  	MatchedHits[HitLayer] = MatchedHits[HitLayer] || ( PatternHitWords[HitLayer] == HitWord );
	
      }
      
      if ((MatchedHits[5]==true) && 
  	  (MatchedHits[7]==true) && 
  	  (MatchedHits[9]==true) &&
  	  (MatchedHits[10]==true) && 
  	  (MatchedHits[11]==true) && 
  	  (MatchedHits[12]==true) &&
  	  (MatchedHits[13]==true) && 
  	  (MatchedHits[14]==true))
  	{
	  PtEff->Fill(true, trackPt);
  	  nMatchedPatterns++;
  	  matchedPt->Fill(trackPt);
  	}
      else PtEff->Fill(false, trackPt);
    }
    
    cout << "One event checked; " << nMatchedPatterns << " was matched." << endl;
 
    }

  cout << nMatchedPatterns << " patterns were matched" << endl;

  TCanvas* c1 = new TCanvas("example","",600,400);
  c1->SetFillStyle(1001);
  c1->SetFillColor(kWhite);
  PtEff -> Draw(); 
  
  gROOT->cd();
  TFile * resultFile = new TFile("out/MatchingResults/MatchingResultsStd_visible_SSW16.root","Recreate");
  matchedPt->Write();
  PtEff -> Write();
  
  resultFile->Close();
  PatternFile.Close();
  HitFile.Close();

  
}

Any who has any idea where the slowness comes from or have any tips on flags to have when i compile ?

ROOT Version: Not Provided
Platform: Not Provided
Compiler: Not Provided

2

Maybe using RDataFrame or TTreeReader could help?

3

Using RDataFrame or TTreeReader would let you automate one missing part in the code you pasted. Namely you do not need to read the while entry/files:

PatternTree->GetEntry(iPattern);

but rather you can read just the branch you need

TBranch *br_HitWord_5 = nullptr;
PatternTree->SetBranchAddress("HitWord_5", &PatternHitWords[5], &br_HitWord_5);
....
auto brEntry = PatternTree->LoadTree(iPattern);
...
br_HitWord_5->GetEntry(brEntry);

Cheers,
Philippe.

4

Also I am not sure why your have 3 nested loop where 2 should be enough … maybe:

for(Long64_t iHit = 0; iHit < nEntriesHitTree; iHit++){
    ...
    for (Long64_t iPattern = 0; iPattern < nEntriesPatternTree; iPattern++) {
          ...

In original code the whole HitTree is read nEntriesHitTree * nEntriesPatternTree times …

5

Hello ! Thanks for all of your replies, the issue is solved. The problem was basically i was re-reading stuff that was unnecessary. To see this, one actually need to see the corresponding trees and their structures.

6

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