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[PWGLF] Reduce MC memory usage: reuse vectors per event and shrink every 1000 events #13342

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Merged
alcaliva merged 2 commits into from
Oct 13, 2025
Merged

[PWGLF] Reduce MC memory usage: reuse vectors per event and shrink every 1000 events #13342

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[PWGLF] Reduce MC memory usage: reuse vectors per event and shrink ev…
alcaliva Oct 11, 2025
4319ef9
removed magic number
alcaliva Oct 11, 2025
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51 changes: 45 additions & 6 deletions PWGLF/Tasks/Nuspex/antinucleiInJets.cxx
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Original file line number Diff line number Diff line change
Expand Up @@ -151,6 +151,9 @@ struct AntinucleiInJets {
Configurable<std::string> weightsXi{"weightsXi", "", "weightsXi"};
Configurable<std::string> weightsOmega{"weightsOmega", "", "weightsOmega"};

// Number of events
Configurable<int> shrinkInterval{"shrinkInterval", 1000, "variable that controls how often shrinking happens"};

// Reweighting histograms
TH1F* primaryAntiprotons;
TH1F* primaryAntiLambda;
Expand Down Expand Up @@ -1616,9 +1619,23 @@ struct AntinucleiInJets {
// Generated events
void processJetsMCgen(GenCollisionsMc const& collisions, aod::McParticles const& mcParticles)
{
// Define per-event particle containers
std::vector<fastjet::PseudoJet> fjParticles;
std::vector<TVector3> protonMomentum;

// Event counter
int eventCounter = 0;

// Loop over all simulated collisions
for (const auto& collision : collisions) {

// Increment event counter
eventCounter++;

// Clear containers at the start of the event loop
fjParticles.clear();
protonMomentum.clear();

// Event counter: before event selection
registryMC.fill(HIST("genEvents"), 0.5);

Expand All @@ -1629,9 +1646,7 @@ struct AntinucleiInJets {
// Event counter: after event selection
registryMC.fill(HIST("genEvents"), 1.5);

// Loop over all MC particles
std::vector<fastjet::PseudoJet> fjParticles;
std::vector<TVector3> protonMomentum;
// Loop over MC particles
for (const auto& particle : mcParticles) {

// Select physical primaries within acceptance
Expand All @@ -1644,7 +1659,7 @@ struct AntinucleiInJets {
// Store 3-momentum vectors of antiprotons for further analysis
if (particle.pdgCode() == PDG_t::kProtonBar) {
TVector3 pVec(particle.px(), particle.py(), particle.pz());
protonMomentum.push_back(pVec);
protonMomentum.emplace_back(pVec);
}

// 4-momentum representation of a particle
Expand Down Expand Up @@ -1754,16 +1769,36 @@ struct AntinucleiInJets {
if (isAtLeastOneJetSelected) {
registryMC.fill(HIST("genEvents"), 3.5);
}

// Shrink large vectors
if (eventCounter % shrinkInterval == 0) {
fjParticles.shrink_to_fit();
protonMomentum.shrink_to_fit();
}
}
}
PROCESS_SWITCH(AntinucleiInJets, processJetsMCgen, "process jets mc gen", false);

// Reconstructed events
void processJetsMCrec(RecCollisionsMc const& collisions, AntiNucleiTracksMc const& mcTracks, McParticles const&)
{
// Define per-event containers
std::vector<fastjet::PseudoJet> fjParticles;
std::vector<int> antiprotonTrackIndex;

// Event counter
int eventCounter = 0;

// Loop over all reconstructed collisions
for (const auto& collision : collisions) {

// Increment event counter
eventCounter++;

// Clear containers at the start of the event loop
fjParticles.clear();
antiprotonTrackIndex.clear();

// Event counter: before event selection
registryMC.fill(HIST("recEvents"), 0.5);

Expand Down Expand Up @@ -1806,8 +1841,6 @@ struct AntinucleiInJets {

// Loop over reconstructed tracks
int id(-1);
std::vector<fastjet::PseudoJet> fjParticles;
std::vector<int> antiprotonTrackIndex;
for (auto const& track : mcTracks) {
id++;

Expand Down Expand Up @@ -2028,6 +2061,12 @@ struct AntinucleiInJets {
if (isAtLeastOneJetSelected) {
registryMC.fill(HIST("recEvents"), 9.5);
}

// Shrink large vectors
if (eventCounter % shrinkInterval == 0) {
fjParticles.shrink_to_fit();
antiprotonTrackIndex.shrink_to_fit();
}
}
}
PROCESS_SWITCH(AntinucleiInJets, processJetsMCrec, "process jets MC rec", false);
Expand Down
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