From bdfd19d3fe6ebee29d42770d4560ec9a4a0610ab Mon Sep 17 00:00:00 2001
From: Chris Jones <chrisdjones15@gmail.com>
Date: Fri, 12 Apr 2024 10:53:51 -0500
Subject: [PATCH] Fix memory use when writing ParameterSets to files

When forwarding a VPSet from the input file to the output, avoid
calling vpset() which triggers creating the entire vector.
---
 FWCore/ParameterSet/src/ParameterSet.cc       | 2 +-
 FWCore/ParameterSet/src/VParameterSetEntry.cc | 4 +++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/FWCore/ParameterSet/src/ParameterSet.cc b/FWCore/ParameterSet/src/ParameterSet.cc
index d22f363866c40..9909c239fda81 100644
--- a/FWCore/ParameterSet/src/ParameterSet.cc
+++ b/FWCore/ParameterSet/src/ParameterSet.cc
@@ -507,7 +507,7 @@ namespace edm {
       if (useAll || b->second.isTracked()) {
         size += 2;
         size += b->first.size();
-        size += sizeof(ParameterSetID) * b->second.vpset().size();
+        size += sizeof(ParameterSetID) * b->second.size();
       }
     }
 
diff --git a/FWCore/ParameterSet/src/VParameterSetEntry.cc b/FWCore/ParameterSet/src/VParameterSetEntry.cc
index 79fdc007cbcaf..7f464a95cb75e 100644
--- a/FWCore/ParameterSet/src/VParameterSetEntry.cc
+++ b/FWCore/ParameterSet/src/VParameterSetEntry.cc
@@ -102,7 +102,9 @@ namespace edm {
     return theVPSet_->at(i);
   }
 
-  std::vector<ParameterSet>::size_type VParameterSetEntry::size() const { return vpset().size(); }
+  std::vector<ParameterSet>::size_type VParameterSetEntry::size() const {
+    return theIDs_ ? theIDs_->size() : (theVPSet_ ? vpset().size() : 0);
+  }
 
   void VParameterSetEntry::registerPsetsAndUpdateIDs() {
     fillVPSet();