diff --git a/MuonSpectrometer/MuonCnv/MuonSTGC_CnvTools/MuonSTGC_CnvTools/ATLAS_CHECK_THREAD_SAFETY b/MuonSpectrometer/MuonCnv/MuonSTGC_CnvTools/MuonSTGC_CnvTools/ATLAS_CHECK_THREAD_SAFETY
new file mode 100644
index 0000000000000000000000000000000000000000..b7145fa6fabbab22888c3fe58964df4de4e3d50a
--- /dev/null
+++ b/MuonSpectrometer/MuonCnv/MuonSTGC_CnvTools/MuonSTGC_CnvTools/ATLAS_CHECK_THREAD_SAFETY
@@ -0,0 +1 @@
+MuonSpectrometer/MuonCnv/MuonSTGC_CnvTools
diff --git a/MuonSpectrometer/MuonCnv/MuonSTGC_CnvTools/src/components/MuonSTGC_CnvTools_entries.cxx b/MuonSpectrometer/MuonCnv/MuonSTGC_CnvTools/src/components/MuonSTGC_CnvTools_entries.cxx
index c249d49651457e7013b75e3c8ca33fbc45fa1047..b6b509d138b69817d30178a751e57f3e18a99d97 100644
--- a/MuonSpectrometer/MuonCnv/MuonSTGC_CnvTools/src/components/MuonSTGC_CnvTools_entries.cxx
+++ b/MuonSpectrometer/MuonCnv/MuonSTGC_CnvTools/src/components/MuonSTGC_CnvTools_entries.cxx
@@ -5,7 +5,6 @@
 #include "../STGC_RDO_Decoder.h"
 
 DECLARE_COMPONENT( Muon::sTgcRdoToPrepDataTool )
-DECLARE_COMPONENT( Muon::sTgcRdoToPrepDataToolCore )
 DECLARE_COMPONENT( Muon::sTgcRdoToPrepDataToolMT )
 DECLARE_COMPONENT( Muon::STGC_RawDataProviderTool )
 DECLARE_COMPONENT( Muon::STGC_RDO_Decoder )
diff --git a/MuonSpectrometer/MuonCnv/MuonSTGC_CnvTools/src/sTgcRdoToPrepDataTool.cxx b/MuonSpectrometer/MuonCnv/MuonSTGC_CnvTools/src/sTgcRdoToPrepDataTool.cxx
index fab1e0957ad765e5cbe24aa956723b7c2dab6061..3ecf3b4989a13c3791a0c1341b244e0cf17b7c7e 100644
--- a/MuonSpectrometer/MuonCnv/MuonSTGC_CnvTools/src/sTgcRdoToPrepDataTool.cxx
+++ b/MuonSpectrometer/MuonCnv/MuonSTGC_CnvTools/src/sTgcRdoToPrepDataTool.cxx
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2002-2019 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
 ///////////////////////////////////////////////////////////////////
@@ -27,22 +27,19 @@ StatusCode Muon::sTgcRdoToPrepDataTool::initialize()
   return StatusCode::SUCCESS;
 }
 
-Muon::sTgcRdoToPrepDataToolCore::SetupSTGC_PrepDataContainerStatus Muon::sTgcRdoToPrepDataTool::setupSTGC_PrepDataContainer() 
+Muon::sTgcPrepDataContainer* Muon::sTgcRdoToPrepDataTool::setupSTGC_PrepDataContainer() const
 {
 
   if(!evtStore()->contains<Muon::sTgcPrepDataContainer>(m_stgcPrepDataContainerKey.key())){    
-    m_fullEventDone=false;
-    
     SG::WriteHandle< Muon::sTgcPrepDataContainer > handle(m_stgcPrepDataContainerKey);
     StatusCode status = handle.record(std::make_unique<Muon::sTgcPrepDataContainer>(m_idHelperSvc->stgcIdHelper().module_hash_max()));
     
     if (status.isFailure() || !handle.isValid() )   {
       ATH_MSG_FATAL("Could not record container of STGC PrepData Container at " << m_stgcPrepDataContainerKey.key()); 
-      return FAILED;
+      return nullptr;
     }
     m_stgcPrepDataContainer = handle.ptr();
-    return ADDED;
     
   }
-  return ALREADYCONTAINED;
+  return m_stgcPrepDataContainer;
 }
diff --git a/MuonSpectrometer/MuonCnv/MuonSTGC_CnvTools/src/sTgcRdoToPrepDataTool.h b/MuonSpectrometer/MuonCnv/MuonSTGC_CnvTools/src/sTgcRdoToPrepDataTool.h
index 20efd765bad9cebe55544c994a3d15e4a8d8ffa8..177450d26bfa5c31a0ca4532533761d5eaa10395 100644
--- a/MuonSpectrometer/MuonCnv/MuonSTGC_CnvTools/src/sTgcRdoToPrepDataTool.h
+++ b/MuonSpectrometer/MuonCnv/MuonSTGC_CnvTools/src/sTgcRdoToPrepDataTool.h
@@ -6,6 +6,7 @@
 #define MUONTGC_CNVTOOLS_STGCRDOTOPREPDATATOOL
 
 #include "sTgcRdoToPrepDataToolCore.h"
+#include "CxxUtils/checker_macros.h"
 
 namespace Muon 
 {
@@ -13,7 +14,7 @@ namespace Muon
    *  This is the algorithm that convert STGC Raw data  To STGC PRD  as a tool.
    */  
 
-  class sTgcRdoToPrepDataTool : virtual public sTgcRdoToPrepDataToolCore
+  class ATLAS_NOT_THREAD_SAFE sTgcRdoToPrepDataTool : virtual public sTgcRdoToPrepDataToolCore
     {
     public:
       /** Constructor */
@@ -26,7 +27,10 @@ namespace Muon
       virtual StatusCode initialize() override;
 
     protected:
-      virtual SetupSTGC_PrepDataContainerStatus setupSTGC_PrepDataContainer() override;
+      virtual Muon::sTgcPrepDataContainer* setupSTGC_PrepDataContainer() const override;
+
+    private:
+      mutable Muon::sTgcPrepDataContainer* m_stgcPrepDataContainer = nullptr;
    }; 
 } // end of namespace
 
diff --git a/MuonSpectrometer/MuonCnv/MuonSTGC_CnvTools/src/sTgcRdoToPrepDataToolCore.cxx b/MuonSpectrometer/MuonCnv/MuonSTGC_CnvTools/src/sTgcRdoToPrepDataToolCore.cxx
index e4dd433516c93ffbce23291c1f98fb50219e0b51..86b35a3f8035fe37a9bd7c5fcbe784e9483a5123 100644
--- a/MuonSpectrometer/MuonCnv/MuonSTGC_CnvTools/src/sTgcRdoToPrepDataToolCore.cxx
+++ b/MuonSpectrometer/MuonCnv/MuonSTGC_CnvTools/src/sTgcRdoToPrepDataToolCore.cxx
@@ -12,9 +12,7 @@ using namespace Trk;
 using namespace Muon;
 
 Muon::sTgcRdoToPrepDataToolCore::sTgcRdoToPrepDataToolCore(const std::string& t, const std::string& n, const IInterface* p) :
-  AthAlgTool(t,n,p),
-  m_fullEventDone(false),
-  m_stgcPrepDataContainer(0)
+  AthAlgTool(t,n,p)
 {
   declareInterface<Muon::IMuonRdoToPrepDataTool>(this);
   
@@ -38,7 +36,8 @@ StatusCode Muon::sTgcRdoToPrepDataToolCore::initialize()
   return StatusCode::SUCCESS;
 }
 
-StatusCode Muon::sTgcRdoToPrepDataToolCore::processCollection(const STGC_RawDataCollection *rdoColl, std::vector<IdentifierHash>& idWithDataVect)
+StatusCode Muon::sTgcRdoToPrepDataToolCore::processCollection(Muon::sTgcPrepDataContainer* stgcPrepDataContainer,
+                                                              const STGC_RawDataCollection *rdoColl, std::vector<IdentifierHash>& idWithDataVect) const
 {
 
   const IdentifierHash hash = rdoColl->identifyHash();
@@ -48,7 +47,7 @@ StatusCode Muon::sTgcRdoToPrepDataToolCore::processCollection(const STGC_RawData
   sTgcPrepDataCollection* prdColl = nullptr;
   
   // check if the collection already exists, otherwise add it
-  if ( m_stgcPrepDataContainer->indexFindPtr(hash) != nullptr ) {
+  if ( stgcPrepDataContainer->indexFindPtr(hash) != nullptr ) {
 
     ATH_MSG_DEBUG("In processCollection: collection already contained in the MM PrepData container");
     return StatusCode::FAILURE;
@@ -68,7 +67,7 @@ StatusCode Muon::sTgcRdoToPrepDataToolCore::processCollection(const STGC_RawData
       prdColl->setIdentifier(moduleId);
     }
 
-    if (StatusCode::SUCCESS != m_stgcPrepDataContainer->addCollection(prdColl, hash)) {
+    if (StatusCode::SUCCESS != stgcPrepDataContainer->addCollection(prdColl, hash)) {
       ATH_MSG_DEBUG("In processCollection - Couldn't record in the Container MM Collection with hashID = "
 		    << (int)hash );
       return StatusCode::FAILURE;
@@ -270,28 +269,7 @@ StatusCode Muon::sTgcRdoToPrepDataToolCore::processCollection(const STGC_RawData
 }
 
 
-Muon::sTgcRdoToPrepDataToolCore::SetupSTGC_PrepDataContainerStatus Muon::sTgcRdoToPrepDataToolCore::setupSTGC_PrepDataContainer() 
-{
-
-  if(!evtStore()->contains<Muon::sTgcPrepDataContainer>(m_stgcPrepDataContainerKey.key())){    
-    m_fullEventDone=false;
-    
-    SG::WriteHandle< Muon::sTgcPrepDataContainer > handle(m_stgcPrepDataContainerKey);
-    StatusCode status = handle.record(std::make_unique<Muon::sTgcPrepDataContainer>(m_idHelperSvc->stgcIdHelper().module_hash_max()));
-    
-    if (status.isFailure() || !handle.isValid() )   {
-      ATH_MSG_FATAL("Could not record container of STGC PrepData Container at " << m_stgcPrepDataContainerKey.key()); 
-      return FAILED;
-    }
-    m_stgcPrepDataContainer = handle.ptr();
-    return ADDED;
-    
-  }
-  return ALREADYCONTAINED;
-}
-
-
-const STGC_RawDataContainer* Muon::sTgcRdoToPrepDataToolCore::getRdoContainer() {
+const STGC_RawDataContainer* Muon::sTgcRdoToPrepDataToolCore::getRdoContainer() const {
 
   auto rdoContainerHandle  = SG::makeHandle(m_rdoContainerKey);
   if(rdoContainerHandle.isValid()) {
@@ -304,7 +282,8 @@ const STGC_RawDataContainer* Muon::sTgcRdoToPrepDataToolCore::getRdoContainer()
 }
 
 
-void Muon::sTgcRdoToPrepDataToolCore::processRDOContainer( std::vector<IdentifierHash>& idWithDataVect ) 
+void Muon::sTgcRdoToPrepDataToolCore::processRDOContainer( Muon::sTgcPrepDataContainer* stgcPrepDataContainer,
+                                                           std::vector<IdentifierHash>& idWithDataVect ) const
 {
 
 
@@ -321,7 +300,7 @@ void Muon::sTgcRdoToPrepDataToolCore::processRDOContainer( std::vector<Identifie
     if (rdoColl->empty()) continue;
     ATH_MSG_DEBUG("New RDO collection with " << rdoColl->size() << "STGC Hits");
 
-    if(processCollection(rdoColl, idWithDataVect).isFailure()) {
+    if(processCollection(stgcPrepDataContainer, rdoColl, idWithDataVect).isFailure()) {
       ATH_MSG_DEBUG("processCsm returns a bad StatusCode - keep going for new data collections in this event");
     }
   } 
@@ -333,28 +312,21 @@ void Muon::sTgcRdoToPrepDataToolCore::processRDOContainer( std::vector<Identifie
 
 // methods for ROB-based decoding
 StatusCode Muon::sTgcRdoToPrepDataToolCore::decode( std::vector<IdentifierHash>& idVect, 
-						std::vector<IdentifierHash>& idWithDataVect )
+                                                    std::vector<IdentifierHash>& idWithDataVect )
 {
 
   ATH_MSG_DEBUG("Size of the input hash id vector: " << idVect.size());
 
   // clear the output vector of selected data
   idWithDataVect.clear();
-  
-  SetupSTGC_PrepDataContainerStatus containerRecordStatus = setupSTGC_PrepDataContainer();
 
-  if ( containerRecordStatus == FAILED ) {
-    return StatusCode::FAILURE;
-  } 
-
-  processRDOContainer(idWithDataVect);
+  Muon::sTgcPrepDataContainer* stgcPrepDataContainer = setupSTGC_PrepDataContainer();
 
-  // check if the full event has already been decoded
-  if ( m_fullEventDone ) {
-    ATH_MSG_DEBUG ("Full event dcoded, nothing to do");
-    return StatusCode::SUCCESS;
+  if ( stgcPrepDataContainer == nullptr ) {
+    return StatusCode::FAILURE;
   } 
 
+  processRDOContainer(stgcPrepDataContainer, idWithDataVect);
 
   return StatusCode::SUCCESS;
 } 
diff --git a/MuonSpectrometer/MuonCnv/MuonSTGC_CnvTools/src/sTgcRdoToPrepDataToolCore.h b/MuonSpectrometer/MuonCnv/MuonSTGC_CnvTools/src/sTgcRdoToPrepDataToolCore.h
index 76a7d6ca668b7953ea31695df98072f5fbaf68d9..d7f66ca3c351e114e93f1f8d5daf6e3d9beaeb79 100644
--- a/MuonSpectrometer/MuonCnv/MuonSTGC_CnvTools/src/sTgcRdoToPrepDataToolCore.h
+++ b/MuonSpectrometer/MuonCnv/MuonSTGC_CnvTools/src/sTgcRdoToPrepDataToolCore.h
@@ -49,8 +49,9 @@ namespace Muon
       StatusCode decode(const std::vector<uint32_t>& robIds) override;
 
       
-      StatusCode processCollection(const STGC_RawDataCollection *rdoColl, 
-				   std::vector<IdentifierHash>& idWithDataVect);
+      StatusCode processCollection(Muon::sTgcPrepDataContainer* stgcPrepDataContainer,
+                                   const STGC_RawDataCollection *rdoColl, 
+				   std::vector<IdentifierHash>& idWithDataVect) const;
 
       virtual void printPrepData() override;
       virtual void printInputRdo() override;
@@ -60,25 +61,19 @@ namespace Muon
       
     protected:
       
-      enum SetupSTGC_PrepDataContainerStatus {
-	FAILED = 0, ADDED, ALREADYCONTAINED
-      };
+      virtual Muon::sTgcPrepDataContainer* setupSTGC_PrepDataContainer() const = 0;
 
-      virtual SetupSTGC_PrepDataContainerStatus setupSTGC_PrepDataContainer();
+      const STGC_RawDataContainer* getRdoContainer() const;
 
-      const STGC_RawDataContainer* getRdoContainer();
-
-      void processRDOContainer(std::vector<IdentifierHash>& idWithDataVect);
+      void processRDOContainer(Muon::sTgcPrepDataContainer* stgcPrepDataContainer,
+                               std::vector<IdentifierHash>& idWithDataVect) const;
 
       SG::ReadCondHandleKey<MuonGM::MuonDetectorManager> m_muDetMgrKey {this, "DetectorManagerKey", "MuonDetectorManager", "Key of input MuonDetectorManager condition data"}; 
 
       ServiceHandle<Muon::IMuonIdHelperSvc> m_idHelperSvc {this, "MuonIdHelperSvc", "Muon::MuonIdHelperSvc/MuonIdHelperSvc"};
 
-      bool m_fullEventDone;
-
       /** TgcPrepRawData container key for current BC */ 
       std::string m_outputCollectionLocation;      
-      Muon::sTgcPrepDataContainer* m_stgcPrepDataContainer;
       SG::ReadHandleKey<STGC_RawDataContainer> m_rdoContainerKey;//"TGCRDO"
       SG::WriteHandleKey<sTgcPrepDataContainer> m_stgcPrepDataContainerKey;
       bool m_merge; // merge Prds
diff --git a/MuonSpectrometer/MuonCnv/MuonSTGC_CnvTools/src/sTgcRdoToPrepDataToolMT.cxx b/MuonSpectrometer/MuonCnv/MuonSTGC_CnvTools/src/sTgcRdoToPrepDataToolMT.cxx
index 56181c8d941a59aaa3bf1dabeda1e36f6120c3a7..1c2e4303b119c0370f7e871c384c4bee1003ae94 100644
--- a/MuonSpectrometer/MuonCnv/MuonSTGC_CnvTools/src/sTgcRdoToPrepDataToolMT.cxx
+++ b/MuonSpectrometer/MuonCnv/MuonSTGC_CnvTools/src/sTgcRdoToPrepDataToolMT.cxx
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2002-2019 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
 ///////////////////////////////////////////////////////////////////
@@ -27,22 +27,21 @@ StatusCode Muon::sTgcRdoToPrepDataToolMT::initialize()
   return StatusCode::SUCCESS;
 }
 
-Muon::sTgcRdoToPrepDataToolCore::SetupSTGC_PrepDataContainerStatus Muon::sTgcRdoToPrepDataToolMT::setupSTGC_PrepDataContainer() 
+Muon::sTgcPrepDataContainer* Muon::sTgcRdoToPrepDataToolMT::setupSTGC_PrepDataContainer() const
 {
 
   if(!evtStore()->contains<Muon::sTgcPrepDataContainer>(m_stgcPrepDataContainerKey.key())){    
-    m_fullEventDone=false;
-    
     SG::WriteHandle< Muon::sTgcPrepDataContainer > handle(m_stgcPrepDataContainerKey);
     StatusCode status = handle.record(std::make_unique<Muon::sTgcPrepDataContainer>(m_idHelperSvc->stgcIdHelper().module_hash_max()));
     
     if (status.isFailure() || !handle.isValid() )   {
       ATH_MSG_FATAL("Could not record container of STGC PrepData Container at " << m_stgcPrepDataContainerKey.key()); 
-      return FAILED;
+      return nullptr;
     }
-    m_stgcPrepDataContainer = handle.ptr();
-    return ADDED;
-    
+    return handle.ptr();
   }
-  return ALREADYCONTAINED;
+
+  ATH_MSG_FATAL("STGC PrepData Container " << m_stgcPrepDataContainerKey.key()
+                << " already exists");
+  return nullptr;
 }
diff --git a/MuonSpectrometer/MuonCnv/MuonSTGC_CnvTools/src/sTgcRdoToPrepDataToolMT.h b/MuonSpectrometer/MuonCnv/MuonSTGC_CnvTools/src/sTgcRdoToPrepDataToolMT.h
index 002f58410bfa16e544c7c92630a97598d7101663..60546e861b1e25b7093e95b9907397d7b161d488 100644
--- a/MuonSpectrometer/MuonCnv/MuonSTGC_CnvTools/src/sTgcRdoToPrepDataToolMT.h
+++ b/MuonSpectrometer/MuonCnv/MuonSTGC_CnvTools/src/sTgcRdoToPrepDataToolMT.h
@@ -26,7 +26,7 @@ namespace Muon
       virtual StatusCode initialize() override;
 
     protected:
-      virtual SetupSTGC_PrepDataContainerStatus setupSTGC_PrepDataContainer() override;
+      virtual Muon::sTgcPrepDataContainer* setupSTGC_PrepDataContainer() const override;
    }; 
 } // end of namespace