[Phase2 RelVal] O(100 MB) memory held per event from HGCalGeometry::getGeometry() in PFRecHits

[makortel]

From #45854 (comment)

The container of PFRecHit produced by PFRecHitProducer::produce() ends up holding O(100 MB) memory per event (I suppose the exact value depends on the event itself) allocated in HGCalGeometry::getGeometry() as shown in IgProf profile.

Given the related issue #46433, I think the rationale for creating these geometry elements on the fly should at least documented, if not re-evaluated.

[makortel]

assign geometry, upgrade

[cmsbuild]

New categories assigned: geometry,upgrade

@bsunanda,@civanch,@Dr15Jones,@kpedro88,@makortel,@mdhildreth,@Moanwar,@srimanob,@subirsarkar you have been requested to review this Pull request/Issue and eventually sign? Thanks

[cmsbuild]

cms-bot internal usage

[cmsbuild]

A new Issue was created by @makortel.

@Dr15Jones, @antoniovilela, @makortel, @mandrenguyen, @rappoccio, @sextonkennedy, @smuzaffar can you please review it and eventually sign/assign? Thanks.

cms-bot commands are listed here

[makortel]

@cms-sw/hgcal-dpg-l2

[makortel]

Are the FlatTrd and FlatHexagon copied on the fly in order to save memory?

cmssw/Geometry/HGCalGeometry/src/HGCalGeometry.cc

Lines 699 to 724 in f71ff4c

	std::shared_ptr<const CaloCellGeometry> HGCalGeometry::cellGeomPtr(uint32_t index, const GlobalPoint& pos) const {
	if ((index >= m_cellVec.size() && m_det != DetId::HGCalHSc) ||
	(index >= m_cellVec2.size() && m_det == DetId::HGCalHSc) || (m_validGeomIds[index].rawId() == 0))
	return nullptr;
	if (pos == GlobalPoint())
	return cellGeomPtr(index);
	if (m_det == DetId::HGCalHSc) {
	auto cell = std::make_shared<FlatTrd>(m_cellVec2[index]);
	cell->setPosition(pos);
	#ifdef EDM_ML_DEBUG
	edm::LogVerbatim("HGCalGeom") << "cellGeomPtr " << index << ":" << cell;
	#endif
	if (nullptr == cell->param())
	return nullptr;
	return cell;
	} else {
	auto cell = std::make_shared<FlatHexagon>(m_cellVec[index]);
	cell->setPosition(pos);
	#ifdef EDM_ML_DEBUG
	edm::LogVerbatim("HGCalGeom") << "cellGeomPtr " << index << ":" << cell;
	#endif
	if (nullptr == cell->param())
	return nullptr;
	return cell;
	}
	}

If this is the case, how much memory would be needed to store these all the time?

Or is the rationale something different?

[makortel]

Adding @cms-sw/reconstruction-l2 @cms-sw/pf-l2 because of the connection to PFRecHit

[makortel]

type performance-improvements