Mem improvement for TPC digitization

sawenzel · davidrohr · commit a7f90b236d55 · 2022-07-08T17:07:43.000+02:00
For simulations with low interaction rate, we saw high mem spikes (up to 24GB) coming from TPC digitization. This is due to some preallocation of a std::deque<DigitTime> container. This commit preserves the logic but changes the container to std::deque<DigitTime*> and to a just-in-time creation of the actual DigitTime objects. This will lead to huge mem benefits in case of sparse occupancies and should be equivalent to the old solution for higher occupancies. Fixes https://alice.its.cern.ch/jira/browse/O2-3051
diff --git a/Detectors/TPC/simulation/include/TPCSimulation/DigitContainer.h b/Detectors/TPC/simulation/include/TPCSimulation/DigitContainer.h
@@ -84,7 +84,7 @@ class DigitContainer
   TimeBin mEffectiveTimeBin = 0;   ///< Effective time bin of that digit
   TimeBin mTmaxTriggered = 0;      ///< Maximum time bin in case of triggered mode (hard cut at average drift speed with additional margin)
   TimeBin mOffset;                 ///< Size of the container for one event
-  std::deque<DigitTime> mTimeBins; ///< Time bin Container for the ADC value
+  std::deque<DigitTime*> mTimeBins; ///< Time bin Container for the ADC value
 };
 
 inline DigitContainer::DigitContainer()
@@ -96,30 +96,36 @@ inline DigitContainer::DigitContainer()
 
   // always have 50 % contingency for the size of the container depending on the input
   mOffset = static_cast<TimeBin>(1.5 * detParam.TPClength / gasParam.DriftV / eleParam.ZbinWidth);
-  mTimeBins.resize(mOffset);
+  mTimeBins.resize(mOffset, nullptr);
 }
 
 inline void DigitContainer::reset()
 {
   mFirstTimeBin = 0;
   mEffectiveTimeBin = 0;
   for (auto& time : mTimeBins) {
-    time.reset();
+    if (time) {
+      time->reset();
+    }
   }
 }
 
 inline void DigitContainer::reserve(TimeBin eventTimeBin)
 {
-  if (mTimeBins.size() < mOffset + eventTimeBin - mFirstTimeBin) {
-    mTimeBins.resize(mOffset + eventTimeBin - mFirstTimeBin);
+  const auto space = mOffset + eventTimeBin - mFirstTimeBin;
+  if (mTimeBins.size() < space) {
+    mTimeBins.resize(space);
   }
 }
 
 inline void DigitContainer::addDigit(const MCCompLabel& label, const CRU& cru, TimeBin timeBin, GlobalPadNumber globalPad,
                                      float signal)
 {
   mEffectiveTimeBin = timeBin - mFirstTimeBin;
-  mTimeBins[mEffectiveTimeBin].addDigit(label, cru, globalPad, signal);
+  if (mTimeBins[mEffectiveTimeBin] == nullptr) {
+    mTimeBins[mEffectiveTimeBin] = new DigitTime();
+  }
+  mTimeBins[mEffectiveTimeBin]->addDigit(label, cru, globalPad, signal);
 }
 
 } // namespace tpc
diff --git a/Detectors/TPC/simulation/src/DigitContainer.cxx b/Detectors/TPC/simulation/src/DigitContainer.cxx
@@ -36,27 +36,28 @@ void DigitContainer::fillOutputContainer(std::vector<Digit>& output,
         continue;
       }
       ++nProcessedTimeBins;
-
-      switch (digitizationMode) {
-        case DigitzationMode::FullMode: {
-          time.fillOutputContainer<DigitzationMode::FullMode>(output, mcTruth, commonModeOutput, sector, timeBin);
-          break;
-        }
-        case DigitzationMode::ZeroSuppression: {
-          time.fillOutputContainer<DigitzationMode::ZeroSuppression>(output, mcTruth, commonModeOutput, sector, timeBin);
-          break;
-        }
-        case DigitzationMode::SubtractPedestal: {
-          time.fillOutputContainer<DigitzationMode::SubtractPedestal>(output, mcTruth, commonModeOutput, sector, timeBin);
-          break;
-        }
-        case DigitzationMode::NoSaturation: {
-          time.fillOutputContainer<DigitzationMode::NoSaturation>(output, mcTruth, commonModeOutput, sector, timeBin);
-          break;
-        }
-        case DigitzationMode::PropagateADC: {
-          time.fillOutputContainer<DigitzationMode::PropagateADC>(output, mcTruth, commonModeOutput, sector, timeBin);
-          break;
+      if (time) {
+        switch (digitizationMode) {
+          case DigitzationMode::FullMode: {
+            time->fillOutputContainer<DigitzationMode::FullMode>(output, mcTruth, commonModeOutput, sector, timeBin);
+            break;
+          }
+          case DigitzationMode::ZeroSuppression: {
+            time->fillOutputContainer<DigitzationMode::ZeroSuppression>(output, mcTruth, commonModeOutput, sector, timeBin);
+            break;
+          }
+          case DigitzationMode::SubtractPedestal: {
+            time->fillOutputContainer<DigitzationMode::SubtractPedestal>(output, mcTruth, commonModeOutput, sector, timeBin);
+            break;
+          }
+          case DigitzationMode::NoSaturation: {
+            time->fillOutputContainer<DigitzationMode::NoSaturation>(output, mcTruth, commonModeOutput, sector, timeBin);
+            break;
+          }
+          case DigitzationMode::PropagateADC: {
+            time->fillOutputContainer<DigitzationMode::PropagateADC>(output, mcTruth, commonModeOutput, sector, timeBin);
+            break;
+          }
         }
       }
     } else {
@@ -67,7 +68,11 @@ void DigitContainer::fillOutputContainer(std::vector<Digit>& output,
   if (nProcessedTimeBins > 0) {
     mFirstTimeBin += nProcessedTimeBins;
     while (nProcessedTimeBins--) {
+      auto popped = mTimeBins.front();
       mTimeBins.pop_front();
+      if (popped) {
+        delete popped;
+      }
     }
   }
 }

Original file line number	Diff line number	Diff line change
`@@ -84,7 +84,7 @@ class DigitContainer`
`84`	`84`	`TimeBin mEffectiveTimeBin = 0; ///< Effective time bin of that digit`
`85`	`85`	`TimeBin mTmaxTriggered = 0; ///< Maximum time bin in case of triggered mode (hard cut at average drift speed with additional margin)`
`86`	`86`	`TimeBin mOffset; ///< Size of the container for one event`
`87`		`- std::deque<DigitTime> mTimeBins; ///< Time bin Container for the ADC value`
	`87`	`+ std::deque<DigitTime*> mTimeBins; ///< Time bin Container for the ADC value`
`88`	`88`	`};`
`89`	`89`
`90`	`90`	`inline DigitContainer::DigitContainer()`
`@@ -96,30 +96,36 @@ inline DigitContainer::DigitContainer()`
`96`	`96`
`97`	`97`	`// always have 50 % contingency for the size of the container depending on the input`
`98`	`98`	`mOffset = static_cast<TimeBin>(1.5 * detParam.TPClength / gasParam.DriftV / eleParam.ZbinWidth);`
`99`		`- mTimeBins.resize(mOffset);`
	`99`	`+ mTimeBins.resize(mOffset, nullptr);`
`100`	`100`	`}`
`101`	`101`
`102`	`102`	`inline void DigitContainer::reset()`
`103`	`103`	`{`
`104`	`104`	`mFirstTimeBin = 0;`
`105`	`105`	`mEffectiveTimeBin = 0;`
`106`	`106`	`for (auto& time : mTimeBins) {`
`107`		`- time.reset();`
	`107`	`+ if (time) {`
	`108`	`+ time->reset();`
	`109`	`+ }`
`108`	`110`	`}`
`109`	`111`	`}`
`110`	`112`
`111`	`113`	`inline void DigitContainer::reserve(TimeBin eventTimeBin)`
`112`	`114`	`{`
`113`		`- if (mTimeBins.size() < mOffset + eventTimeBin - mFirstTimeBin) {`
`114`		`- mTimeBins.resize(mOffset + eventTimeBin - mFirstTimeBin);`
	`115`	`+ const auto space = mOffset + eventTimeBin - mFirstTimeBin;`
	`116`	`+ if (mTimeBins.size() < space) {`
	`117`	`+ mTimeBins.resize(space);`
`115`	`118`	`}`
`116`	`119`	`}`
`117`	`120`
`118`	`121`	`inline void DigitContainer::addDigit(const MCCompLabel& label, const CRU& cru, TimeBin timeBin, GlobalPadNumber globalPad,`
`119`	`122`	`float signal)`
`120`	`123`	`{`
`121`	`124`	`mEffectiveTimeBin = timeBin - mFirstTimeBin;`
`122`		`- mTimeBins[mEffectiveTimeBin].addDigit(label, cru, globalPad, signal);`
	`125`	`+ if (mTimeBins[mEffectiveTimeBin] == nullptr) {`
	`126`	`+ mTimeBins[mEffectiveTimeBin] = new DigitTime();`
	`127`	`+ }`
	`128`	`+ mTimeBins[mEffectiveTimeBin]->addDigit(label, cru, globalPad, signal);`
`123`	`129`	`}`
`124`	`130`
`125`	`131`	`} // namespace tpc`