diff --git a/InnerDetector/InDetG4/TRT_G4Utilities/CMakeLists.txt b/InnerDetector/InDetG4/TRT_G4Utilities/CMakeLists.txt
index 0dac0e4616010a328cf7f5827c16f2bccf338191..0c3fdb7f128f357163c0afec50fb5b59cf8911d5 100644
--- a/InnerDetector/InDetG4/TRT_G4Utilities/CMakeLists.txt
+++ b/InnerDetector/InDetG4/TRT_G4Utilities/CMakeLists.txt
@@ -17,7 +17,7 @@ atlas_add_library( TRT_G4Utilities
                    PUBLIC_HEADERS TRT_G4Utilities
                    PRIVATE_INCLUDE_DIRS ${GEANT4_INCLUDE_DIRS} ${XERCESC_INCLUDE_DIRS} ${CLHEP_INCLUDE_DIRS}
                    PRIVATE_DEFINITIONS ${CLHEP_DEFINITIONS}
-                   LINK_LIBRARIES AthenaKernel
+                   LINK_LIBRARIES AthenaKernel CxxUtils
                    PRIVATE_LINK_LIBRARIES ${GEANT4_LIBRARIES} ${XERCESC_LIBRARIES} ${CLHEP_LIBRARIES} PathResolver )
 
 # Install files from the package:
diff --git a/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/ATLAS_CHECK_THREAD_SAFETY b/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/ATLAS_CHECK_THREAD_SAFETY
new file mode 100644
index 0000000000000000000000000000000000000000..f158b05b7ce372c8bac17ecac17be8c1cdf1ae70
--- /dev/null
+++ b/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/ATLAS_CHECK_THREAD_SAFETY
@@ -0,0 +1 @@
+InnerDetector/InDetG4/TRT_G4Utilities
diff --git a/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTOutputFile.hh b/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTOutputFile.hh
index 8a5a66939bc502e990f93a461afe9b8fa80f8866..1ffa44e9a93fe872a83b00d5653b3e65f6979581 100644
--- a/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTOutputFile.hh
+++ b/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTOutputFile.hh
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
 
@@ -9,9 +9,9 @@
 #include "globals.hh"
 #include <fstream>
 #include "AthenaKernel/MsgStreamMember.h"
+#include "CxxUtils/checker_macros.h"
 
-
-class TRTOutputFile
+class ATLAS_NOT_THREAD_SAFE TRTOutputFile // This class needs give non-const reference for output streaming. static TRTOutputFile* m_pOutputFile cannot be static const. Thread unsafe exit is also used.
 {
 public:
   ~TRTOutputFile();
@@ -38,7 +38,7 @@ private:
   
   static TRTOutputFile* m_pOutputFile;
 
-  mutable Athena::MsgStreamMember m_msg;
+  mutable Athena::MsgStreamMember m_msg ATLAS_THREAD_SAFE;
 
 };
 
diff --git a/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTParameters.hh b/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTParameters.hh
index b5b5070c9424ebe5f20aea8e767c10fa1795b95a..70e8f70f714e9cba4c863e9926d0744ecb337bae 100644
--- a/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTParameters.hh
+++ b/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTParameters.hh
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
 
@@ -9,9 +9,9 @@
 #include "globals.hh"
 #include <map>
 #include "AthenaKernel/MsgStreamMember.h"
+#include "CxxUtils/checker_macros.h"
 
-
-class TRTParameters
+class ATLAS_NOT_THREAD_SAFE TRTParameters // static variable and thread unsafe exit are used.
 {
 public:
   ~TRTParameters();
@@ -49,7 +49,7 @@ private:
   
   static TRTParameters* s_pParameters;
 
-  mutable Athena::MsgStreamMember m_msg;
+  mutable Athena::MsgStreamMember m_msg ATLAS_THREAD_SAFE;
 
 };
 
diff --git a/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTParametersOfBarrelStraws.hh b/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTParametersOfBarrelStraws.hh
index bf69026c77f01fb545d40ae5e3379686304d55d6..62d1cb3ec7d92315fe785859a41c20389729ffad 100644
--- a/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTParametersOfBarrelStraws.hh
+++ b/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTParametersOfBarrelStraws.hh
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
 
@@ -8,11 +8,12 @@
 
 #include "globals.hh"
 #include "AthenaKernel/MsgStreamMember.h"
+#include "CxxUtils/checker_macros.h"
 
 class TRTParameters;
 
 
-class TRTParametersOfBarrelStraws
+class ATLAS_NOT_THREAD_SAFE TRTParametersOfBarrelStraws // Thread unsafe TRTParameters class is used.
 {
   friend class TRTConstructionOfBarrelStraws;
 
@@ -62,7 +63,7 @@ class TRTParametersOfBarrelStraws
 
     TRTParameters* m_pParameters;
 
-    mutable Athena::MsgStreamMember m_msg;
+    mutable Athena::MsgStreamMember m_msg ATLAS_THREAD_SAFE;
 
 };
 
diff --git a/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTParametersOfModulesA.hh b/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTParametersOfModulesA.hh
index 3e04472a3f643b1f27eae7f28c7280f8401312ca..61cc54b44570e3795a0ed2bedae090699c65579e 100644
--- a/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTParametersOfModulesA.hh
+++ b/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTParametersOfModulesA.hh
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
 
@@ -8,11 +8,12 @@
 
 #include "globals.hh"
 #include "AthenaKernel/MsgStreamMember.h"
+#include "CxxUtils/checker_macros.h"
 
 class TRTParameters;
 
 
-class TRTParametersOfModulesA
+class ATLAS_NOT_THREAD_SAFE TRTParametersOfModulesA // Thread unsafe TRTParameters class is used.
 {
   friend class TRTConstructionOfModulesA;
   
@@ -73,7 +74,7 @@ private:
   
   TRTParameters* m_pParameters;
   
-  mutable Athena::MsgStreamMember m_msg;
+  mutable Athena::MsgStreamMember m_msg ATLAS_THREAD_SAFE;
 
 };
 
diff --git a/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTParametersOfModulesB.hh b/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTParametersOfModulesB.hh
index 22a3ed10c7d3eb1d70e33efb347229454fc2612e..95b7c0e93bd8f0da1d63f46567da57ffd6855bf9 100644
--- a/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTParametersOfModulesB.hh
+++ b/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTParametersOfModulesB.hh
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
 
@@ -8,11 +8,12 @@
 
 #include "globals.hh"
 #include "AthenaKernel/MsgStreamMember.h"
+#include "CxxUtils/checker_macros.h"
 
 class TRTParameters;
 
 
-class TRTParametersOfModulesB
+class ATLAS_NOT_THREAD_SAFE TRTParametersOfModulesB // Thread unsafe TRTParameters class is used.
 {
   friend class TRTConstructionOfModulesB;
 
@@ -76,7 +77,7 @@ class TRTParametersOfModulesB
 
     TRTParameters* m_pParameters;
 
-    mutable Athena::MsgStreamMember m_msg;
+    mutable Athena::MsgStreamMember m_msg ATLAS_THREAD_SAFE;
 
 };
 
diff --git a/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTParametersOfModulesC.hh b/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTParametersOfModulesC.hh
index ea284bac9c22c504f1bf357475da259e6ba8b460..10a02d6d2d3f06a7af8c9b7db4bc726b652ef49b 100644
--- a/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTParametersOfModulesC.hh
+++ b/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTParametersOfModulesC.hh
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
 
@@ -8,11 +8,12 @@
 
 #include "globals.hh"
 #include "AthenaKernel/MsgStreamMember.h"
+#include "CxxUtils/checker_macros.h"
 
 class TRTParameters;
 
 
-class TRTParametersOfModulesC
+class ATLAS_NOT_THREAD_SAFE TRTParametersOfModulesC // Thread unsafe TRTParameters class is used.
 {
   friend class TRTConstructionOfModulesC;
 
@@ -76,7 +77,7 @@ private:
   
   TRTParameters* m_pParameters;
 
-  mutable Athena::MsgStreamMember m_msg;
+  mutable Athena::MsgStreamMember m_msg ATLAS_THREAD_SAFE;
 
 };
 
diff --git a/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTParametersOfStrawPlanes.hh b/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTParametersOfStrawPlanes.hh
index 9b32a16d0d5cb31a8e5d25921d5082f4bff738df..98373f53ff22794307e4d3a4a4d6303db389733e 100644
--- a/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTParametersOfStrawPlanes.hh
+++ b/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTParametersOfStrawPlanes.hh
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
 
@@ -8,11 +8,12 @@
 
 #include "globals.hh"
 #include "AthenaKernel/MsgStreamMember.h"
+#include "CxxUtils/checker_macros.h"
 
 class TRTParameters;
 
 
-class TRTParametersOfStrawPlanes
+class ATLAS_NOT_THREAD_SAFE TRTParametersOfStrawPlanes // Thread unsafe TRTParameters class is used.
 {
   friend class TRTConstructionOfStrawPlanes;
 
@@ -73,7 +74,7 @@ class TRTParametersOfStrawPlanes
 
     TRTParameters* m_pParameters;
 
-    mutable Athena::MsgStreamMember m_msg;
+    mutable Athena::MsgStreamMember m_msg ATLAS_THREAD_SAFE;
 
 };
 
diff --git a/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTParametersOfWheelsA.hh b/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTParametersOfWheelsA.hh
index ea24aae7b016f94c87612e932a3bd4ce84579361..7076b52b4e8759ed377e228a4f37555470c49631 100644
--- a/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTParametersOfWheelsA.hh
+++ b/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTParametersOfWheelsA.hh
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
 
@@ -8,11 +8,12 @@
 
 #include "globals.hh"
 #include "AthenaKernel/MsgStreamMember.h"
+#include "CxxUtils/checker_macros.h"
 
 class TRTParameters;
 
 
-class TRTParametersOfWheelsA
+class ATLAS_NOT_THREAD_SAFE TRTParametersOfWheelsA // Thread unsafe TRTParameters class is used.
 {
   friend class TRTConstructionOfWheelsA;
 
@@ -67,7 +68,7 @@ class TRTParametersOfWheelsA
 
     TRTParameters* m_pParameters;
   
-    mutable Athena::MsgStreamMember m_msg;
+    mutable Athena::MsgStreamMember m_msg ATLAS_THREAD_SAFE;
 };
 
 #endif
diff --git a/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTParametersOfWheelsB.hh b/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTParametersOfWheelsB.hh
index 4f0988bfba8d381aaf0b53ef66910d476c29ea6d..fbd27905e4da5bc9607356db05185cb6460c4ec6 100644
--- a/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTParametersOfWheelsB.hh
+++ b/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTParametersOfWheelsB.hh
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
 
@@ -8,11 +8,12 @@
 
 #include "globals.hh"
 #include "AthenaKernel/MsgStreamMember.h"
+#include "CxxUtils/checker_macros.h"
 
 class TRTParameters;
 
 
-class TRTParametersOfWheelsB
+class ATLAS_NOT_THREAD_SAFE TRTParametersOfWheelsB // Thread unsafe TRTParameters class is used.
 {
   friend class TRTConstructionOfWheelsB;
 
@@ -74,7 +75,7 @@ class TRTParametersOfWheelsB
 
     TRTParameters* m_pParameters;
   
-    mutable Athena::MsgStreamMember m_msg;
+    mutable Athena::MsgStreamMember m_msg ATLAS_THREAD_SAFE;
 };
 
 #endif
diff --git a/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTParametersOfWheelsC.hh b/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTParametersOfWheelsC.hh
index 841cfcd0708f28d0668cae6d4676ba1b01f0aa32..a3b79e86d930e1bcd6ce153e05247b082cdc2795 100644
--- a/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTParametersOfWheelsC.hh
+++ b/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTParametersOfWheelsC.hh
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
 
@@ -8,11 +8,12 @@
 
 #include "globals.hh"
 #include "AthenaKernel/MsgStreamMember.h"
+#include "CxxUtils/checker_macros.h"
 
 class TRTParameters;
 
 
-class TRTParametersOfWheelsC
+class ATLAS_NOT_THREAD_SAFE TRTParametersOfWheelsC // Thread unsafe TRTParameters class is used.
 {
   friend class TRTConstructionOfWheelsC;
 
@@ -67,7 +68,7 @@ class TRTParametersOfWheelsC
 
     TRTParameters* m_pParameters;
  
-    mutable Athena::MsgStreamMember m_msg;
+    mutable Athena::MsgStreamMember m_msg ATLAS_THREAD_SAFE;
 };
 
 #endif
diff --git a/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTUtilities.hh b/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTUtilities.hh
index 14c224166c47a5ab5c08ee812511df8ce317b721..4f0aaf3bf3cf3384b6fbcfec7e9685efe6de9606 100644
--- a/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTUtilities.hh
+++ b/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTUtilities.hh
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
 #ifndef TRTUtilities_hh
@@ -8,11 +8,12 @@
 #include "globals.hh"
 #include <fstream>
 #include "AthenaKernel/MsgStreamMember.h"
+#include "CxxUtils/checker_macros.h"
 
 class TRTOutputFile;
 
 
-class TRTUtilities
+class ATLAS_NOT_THREAD_SAFE TRTUtilities // This class uses thread unsafe TRTOutputFile. static TRTUtilities utilities cannot be static const for output streaming.
 {
 public:
     ~TRTUtilities();
@@ -42,7 +43,7 @@ private:
   
   static TRTUtilities* s_pUtilities;
 
-  mutable Athena::MsgStreamMember m_msg;
+  mutable Athena::MsgStreamMember m_msg ATLAS_THREAD_SAFE;
 
 };
 
diff --git a/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTVisualization.hh b/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTVisualization.hh
index 32cf5355654e3dc03752bec18dde6ed23e219c83..2e469b410c9ff254815b20021dc09584b8e935e8 100644
--- a/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTVisualization.hh
+++ b/InnerDetector/InDetG4/TRT_G4Utilities/TRT_G4Utilities/TRTVisualization.hh
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
 
@@ -8,12 +8,13 @@
 
 #include "globals.hh"
 #include "AthenaKernel/MsgStreamMember.h"
+#include "CxxUtils/checker_macros.h"
 
 class G4LogicalVolume;
 class G4VisAttributes;
 
 
-class TRTVisualization
+class ATLAS_NOT_THREAD_SAFE TRTVisualization // static variable and thread unsafe exit are used.
 {
   public:
     ~TRTVisualization();
@@ -45,7 +46,7 @@ class TRTVisualization
 
     static TRTVisualization* s_pVisualization;
 
-    mutable Athena::MsgStreamMember m_msg;
+    mutable Athena::MsgStreamMember m_msg ATLAS_THREAD_SAFE;
 
 };
 
diff --git a/InnerDetector/InDetG4/TRT_G4Utilities/src/TRTParameters.cc b/InnerDetector/InDetG4/TRT_G4Utilities/src/TRTParameters.cc
index d3588766d2259dd4fd1c317f1b4d7138d75bd66a..b8692eea93f56ced715c6020e07a9817a6d9d4e9 100644
--- a/InnerDetector/InDetG4/TRT_G4Utilities/src/TRTParameters.cc
+++ b/InnerDetector/InDetG4/TRT_G4Utilities/src/TRTParameters.cc
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
 #include "TRT_G4Utilities/TRTParameters.hh"
@@ -42,7 +42,7 @@ TRTParameters::~TRTParameters()
 
   // Called by TRTParameters
 
-void TRTParameters::ReadInputFile(std::string fileName)
+void TRTParameters::ReadInputFile ATLAS_NOT_THREAD_SAFE (std::string fileName) // Thread unsafe exit function is used.
 {
   if (msgLevel(MSG::VERBOSE)) msg(MSG::VERBOSE) << "######### Method TRTParameters::ReadInputFile" << endmsg;
 
@@ -149,7 +149,7 @@ void TRTParameters::ReadInputFile(std::string fileName)
 
   // Called by TRTParameters
 
-void TRTParameters::PrintListOfParameters() const
+void TRTParameters::PrintListOfParameters ATLAS_NOT_THREAD_SAFE () const // Thread unsafe TRTOutputFile class is used.
 {
   if (msgLevel(MSG::VERBOSE)) msg(MSG::VERBOSE) << "######### Method TRTParameters::PrintListOfParameters" << endmsg;
 
@@ -171,7 +171,7 @@ void TRTParameters::PrintListOfParameters() const
 
   // Called on demand
 
-int TRTParameters::GetInteger(std::string parameterName) const
+int TRTParameters::GetInteger ATLAS_NOT_THREAD_SAFE (std::string parameterName) const // Thread unsafe exit function is used.
 {
   int numberOfItems = m_multimapOfParameters.count(parameterName);
 
@@ -203,7 +203,7 @@ int TRTParameters::GetInteger(std::string parameterName) const
 
   // Called on demand
 
-double TRTParameters::GetDouble(std::string parameterName) const
+double TRTParameters::GetDouble ATLAS_NOT_THREAD_SAFE (std::string parameterName) const // Thread unsafe exit function is used.
 {
   int numberOfItems = m_multimapOfParameters.count(parameterName);
 
@@ -235,7 +235,7 @@ double TRTParameters::GetDouble(std::string parameterName) const
 
   // Called on demand
 
-void TRTParameters::GetIntegerArray(std::string arrayName, int arraySize,
+void TRTParameters::GetIntegerArray ATLAS_NOT_THREAD_SAFE (std::string arrayName, int arraySize, // Thread unsafe exit function is used.
   int* array) const
 {
   int numberOfItems = m_multimapOfParameters.count(arrayName);
@@ -269,7 +269,7 @@ void TRTParameters::GetIntegerArray(std::string arrayName, int arraySize,
 
   // Called on demand
 
-void TRTParameters::GetDoubleArray(std::string arrayName, int arraySize,
+void TRTParameters::GetDoubleArray ATLAS_NOT_THREAD_SAFE (std::string arrayName, int arraySize, // Thread unsafe exit function is used.
   double* array) const
 {
   int numberOfItems = m_multimapOfParameters.count(arrayName);
@@ -303,7 +303,7 @@ void TRTParameters::GetDoubleArray(std::string arrayName, int arraySize,
 
   // Called on demand
 
-void TRTParameters::GetPartOfIntegerArray(std::string arrayName,
+void TRTParameters::GetPartOfIntegerArray ATLAS_NOT_THREAD_SAFE (std::string arrayName, // Thread unsafe exit function is used.
   int numberOfDemandedElements, int* array) const
 {
   int numberOfItems = m_multimapOfParameters.count(arrayName);
@@ -338,7 +338,7 @@ void TRTParameters::GetPartOfIntegerArray(std::string arrayName,
 
   // Called on demand
 
-void TRTParameters::GetPartOfDoubleArray(std::string arrayName,
+void TRTParameters::GetPartOfDoubleArray ATLAS_NOT_THREAD_SAFE (std::string arrayName, // Thread unsafe exit function is used.
   int numberOfDemandedElements, double* array) const
 {
   int numberOfItems = m_multimapOfParameters.count(arrayName);
@@ -373,7 +373,7 @@ void TRTParameters::GetPartOfDoubleArray(std::string arrayName,
 
   // Called on demand
 
-int TRTParameters::GetElementOfIntegerArray(std::string arrayName,
+int TRTParameters::GetElementOfIntegerArray ATLAS_NOT_THREAD_SAFE (std::string arrayName, // Thread unsafe exit function is used.
   int elementIndex) const
 {
   int numberOfItems = m_multimapOfParameters.count(arrayName);
diff --git a/InnerDetector/InDetG4/TRT_G4Utilities/src/TRTParametersOfBarrelStraws.cc b/InnerDetector/InDetG4/TRT_G4Utilities/src/TRTParametersOfBarrelStraws.cc
index 4fe73f26018ed64f939e9b228dabdc27e5a69164..028f16c49ae490f217512633ec94bd7e3df34c89 100644
--- a/InnerDetector/InDetG4/TRT_G4Utilities/src/TRTParametersOfBarrelStraws.cc
+++ b/InnerDetector/InDetG4/TRT_G4Utilities/src/TRTParametersOfBarrelStraws.cc
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
 #include "TRT_G4Utilities/TRTParametersOfBarrelStraws.hh"
@@ -91,7 +91,7 @@ void TRTParametersOfBarrelStraws::DefineParameters()
 
 // Called by TRTParametersOfBarrelStraws
 
-void TRTParametersOfBarrelStraws::PrintParameters() const
+void TRTParametersOfBarrelStraws::PrintParameters ATLAS_NOT_THREAD_SAFE () const // Thread unsafe TRTUtilities and TRTOutputFile classes are used.
 {
   if (msgLevel(MSG::VERBOSE)) msg(MSG::VERBOSE) << "######### Method TRTParametersOfBarrelStraws::PrintParameters"
 						<< endmsg;
diff --git a/InnerDetector/InDetG4/TRT_G4Utilities/src/TRTParametersOfStrawPlanes.cc b/InnerDetector/InDetG4/TRT_G4Utilities/src/TRTParametersOfStrawPlanes.cc
index 570957533d51bdea3e7059db20481220f921d1e6..660ccce572943e7b78965d5a947f65ea4a03be66 100644
--- a/InnerDetector/InDetG4/TRT_G4Utilities/src/TRTParametersOfStrawPlanes.cc
+++ b/InnerDetector/InDetG4/TRT_G4Utilities/src/TRTParametersOfStrawPlanes.cc
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-20120 CERN for the benefit of the ATLAS collaboration
 */
 
 
@@ -130,7 +130,7 @@ void TRTParametersOfStrawPlanes::DefineParameters()
 
   // Called by TRTParametersOfStrawPlanes
 
-void TRTParametersOfStrawPlanes::PrintParameters() const
+void TRTParametersOfStrawPlanes::PrintParameters ATLAS_NOT_THREAD_SAFE () const // Thread unsafe TRTUtilities and TRTOutputFile classes are used.
 {
   if (msgLevel(MSG::VERBOSE)) msg(MSG::VERBOSE) << "######### Method TRTParametersOfStrawPlanes::PrintParameters" << endmsg;
 
diff --git a/InnerDetector/InDetG4/TRT_G4Utilities/src/TRTParametersOfWheelsA.cc b/InnerDetector/InDetG4/TRT_G4Utilities/src/TRTParametersOfWheelsA.cc
index f24e8aeb19682022ced68d28cd86774ba04f6cf9..234e8fd99325e5b59e3e9f21193257679319f9f7 100644
--- a/InnerDetector/InDetG4/TRT_G4Utilities/src/TRTParametersOfWheelsA.cc
+++ b/InnerDetector/InDetG4/TRT_G4Utilities/src/TRTParametersOfWheelsA.cc
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
 
@@ -134,7 +134,7 @@ void TRTParametersOfWheelsA::DefineParameters()
 
   // Called by TRTParametersOfWheelsA
 
-void TRTParametersOfWheelsA::PrintParameters() const
+void TRTParametersOfWheelsA::PrintParameters ATLAS_NOT_THREAD_SAFE () const // Thread unsafe TRTUtilities and TRTOutputFile classes are used.
 {
   if (msgLevel(MSG::VERBOSE)) msg(MSG::VERBOSE) << "######### Method TRTParametersOfWheelsA::PrintParameters" << endmsg;
 
diff --git a/InnerDetector/InDetG4/TRT_G4Utilities/src/TRTParametersOfWheelsB.cc b/InnerDetector/InDetG4/TRT_G4Utilities/src/TRTParametersOfWheelsB.cc
index 050246fdb82f91b41c2ea735d5f8596f9778e5fe..f466a0cc18f08bae7d018f1da9e75b2fb10bf835 100644
--- a/InnerDetector/InDetG4/TRT_G4Utilities/src/TRTParametersOfWheelsB.cc
+++ b/InnerDetector/InDetG4/TRT_G4Utilities/src/TRTParametersOfWheelsB.cc
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
 
@@ -146,7 +146,7 @@ void TRTParametersOfWheelsB::DefineParameters()
 
   // Called by TRTParametersOfWheelsB
 
-void TRTParametersOfWheelsB::PrintParameters() const
+void TRTParametersOfWheelsB::PrintParameters ATLAS_NOT_THREAD_SAFE () const // Thread unsafe TRTUtilities and TRTOutputFile classes are used.
 {
   if (msgLevel(MSG::VERBOSE)) msg(MSG::VERBOSE) << "######### Method TRTParametersOfWheelsB::PrintParameters" << endmsg;
 
diff --git a/InnerDetector/InDetG4/TRT_G4Utilities/src/TRTParametersOfWheelsC.cc b/InnerDetector/InDetG4/TRT_G4Utilities/src/TRTParametersOfWheelsC.cc
index 801a5534be7a9231463ea277c410ab74a48d7201..7edacf4ed66e043cfccbfb05ca46ed24c470b34f 100644
--- a/InnerDetector/InDetG4/TRT_G4Utilities/src/TRTParametersOfWheelsC.cc
+++ b/InnerDetector/InDetG4/TRT_G4Utilities/src/TRTParametersOfWheelsC.cc
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
 
@@ -134,7 +134,7 @@ void TRTParametersOfWheelsC::DefineParameters()
 
   // Called by TRTParametersOfWheelsC
 
-void TRTParametersOfWheelsC::PrintParameters() const
+void TRTParametersOfWheelsC::PrintParameters ATLAS_NOT_THREAD_SAFE () const // Thread unsafe TRTUtilities and TRTOutputFile classes are used.
 {
   if (msgLevel(MSG::VERBOSE)) msg(MSG::VERBOSE) << "######### Method TRTParametersOfWheelsC::PrintParameters" << endmsg;
 
diff --git a/InnerDetector/InDetG4/TRT_G4Utilities/test/ut_TRTParametersTest.cxx b/InnerDetector/InDetG4/TRT_G4Utilities/test/ut_TRTParametersTest.cxx
index b697f5213c966af0f9ffa0a4af74b8cf46023d57..ab30309f4b96caa87426f3656e4a77404b2ff83c 100644
--- a/InnerDetector/InDetG4/TRT_G4Utilities/test/ut_TRTParametersTest.cxx
+++ b/InnerDetector/InDetG4/TRT_G4Utilities/test/ut_TRTParametersTest.cxx
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
 #define BOOST_TEST_DYN_LINK
@@ -9,6 +9,8 @@
 #include "TRT_G4Utilities/TRTParameters.hh"
 #include "TRT_G4Utilities/TRTOutputFile.hh"
 
+ATLAS_NO_CHECK_FILE_THREAD_SAFETY; // This unit test uses thread unsafe TRTParameters and TRTOutputFile classes.
+
 namespace utf = boost::unit_test;
 
 struct setupParameters{
diff --git a/InnerDetector/InDetG4/TRT_G4_SD/src/TRTParametersForBarrelHits.cxx b/InnerDetector/InDetG4/TRT_G4_SD/src/TRTParametersForBarrelHits.cxx
index 20979f06e826e7bb311e972e6d63770170dc1a5f..c5ca836bcee8b50e7dc54131ac97b5b0d434ff85 100644
--- a/InnerDetector/InDetG4/TRT_G4_SD/src/TRTParametersForBarrelHits.cxx
+++ b/InnerDetector/InDetG4/TRT_G4_SD/src/TRTParametersForBarrelHits.cxx
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
 // Class header
@@ -154,7 +154,7 @@ void TRTParametersForBarrelHits::DefineParameters() const
 
 // Called by TRTParametersForBarrelHits
 
-void TRTParametersForBarrelHits::PrintParameters() const
+void TRTParametersForBarrelHits::PrintParameters ATLAS_NOT_THREAD_SAFE () const // Thread unsafe TRTOutputFile is used.
 {
 
   if (m_verboseLevel>5) { G4cout << "######### Method TRTParametersForBarrelHits::PrintParameters" << G4endl; }
diff --git a/InnerDetector/InDetG4/TRT_G4_SD/src/TRTParametersForBarrelHits.h b/InnerDetector/InDetG4/TRT_G4_SD/src/TRTParametersForBarrelHits.h
index f1a40f0ccfd3d6d74fdf9f49396aa9795651e3cb..541580f50800ee96f9d8bdefb7c6f3263684e3ee 100644
--- a/InnerDetector/InDetG4/TRT_G4_SD/src/TRTParametersForBarrelHits.h
+++ b/InnerDetector/InDetG4/TRT_G4_SD/src/TRTParametersForBarrelHits.h
@@ -1,14 +1,16 @@
 /*
-  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
 #ifndef TRT_G4_SD_TRTParametersForBarrelHits_hh
 #define TRT_G4_SD_TRTParametersForBarrelHits_hh
 
+#include "CxxUtils/checker_macros.h"
+
 class TRTParameters;
 class TRTProcessingOfBarrelHits;
 
-class TRTParametersForBarrelHits
+class ATLAS_NOT_THREAD_SAFE TRTParametersForBarrelHits // Thread unsafe TRTParameters and TRTProcessingOfBarrelHits classes are used.
 {
 public:
   TRTParametersForBarrelHits(TRTProcessingOfBarrelHits*);
diff --git a/InnerDetector/InDetG4/TRT_G4_SD/src/TRTParametersForEndCapHits.cxx b/InnerDetector/InDetG4/TRT_G4_SD/src/TRTParametersForEndCapHits.cxx
index c27b83c12722f97b820eb4a1e0ccd4fa1b9e92d8..080e2776426c5268e4c8efc9442bc075a4616c08 100644
--- a/InnerDetector/InDetG4/TRT_G4_SD/src/TRTParametersForEndCapHits.cxx
+++ b/InnerDetector/InDetG4/TRT_G4_SD/src/TRTParametersForEndCapHits.cxx
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
 // Class header
@@ -102,7 +102,7 @@ void TRTParametersForEndCapHits::DefineParameters() const
 
 // Called by TRTParametersForEndCapHits
 
-void TRTParametersForEndCapHits::PrintParameters() const
+void TRTParametersForEndCapHits::PrintParameters ATLAS_NOT_THREAD_SAFE () const // Thread unsafe TRTOutputFile class is used.
 {
   if (m_verboseLevel>5) { G4cout << "######### Method TRTParametersForEndCapHits::PrintParameters" << G4endl; }
 
diff --git a/InnerDetector/InDetG4/TRT_G4_SD/src/TRTParametersForEndCapHits.h b/InnerDetector/InDetG4/TRT_G4_SD/src/TRTParametersForEndCapHits.h
index 01ddaee4e73ff533513f3fe9b1ba407d2101f8f0..af25dcf46a0e60acb6d94e4aa81f1b5af5e9c3cb 100644
--- a/InnerDetector/InDetG4/TRT_G4_SD/src/TRTParametersForEndCapHits.h
+++ b/InnerDetector/InDetG4/TRT_G4_SD/src/TRTParametersForEndCapHits.h
@@ -1,14 +1,16 @@
 /*
-  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
 #ifndef TRT_G4_SD_TRTParametersForEndCapHits_hh
 #define TRT_G4_SD_TRTParametersForEndCapHits_hh
 
+#include "CxxUtils/checker_macros.h"
+
 class TRTParameters;
 class TRTProcessingOfEndCapHits;
 
-class TRTParametersForEndCapHits
+class ATLAS_NOT_THREAD_SAFE TRTParametersForEndCapHits // Thread unsafe TRTParameters and TRTProcessingOfEndCapHits classes are used.
 {
 public:
   TRTParametersForEndCapHits(TRTProcessingOfEndCapHits*);
diff --git a/InnerDetector/InDetG4/TRT_G4_SD/src/TRTPrintingOfHits.h b/InnerDetector/InDetG4/TRT_G4_SD/src/TRTPrintingOfHits.h
index 02c6169617e23501062d5a2846d12d31b16d9694..abe80a0441e4f165e23cd9400330ab0ce5de9f98 100644
--- a/InnerDetector/InDetG4/TRT_G4_SD/src/TRTPrintingOfHits.h
+++ b/InnerDetector/InDetG4/TRT_G4_SD/src/TRTPrintingOfHits.h
@@ -12,7 +12,7 @@
 class TRTUncompressedHit;
 class TRTOutputFile;
 
-class TRTPrintingOfHits
+class ATLAS_NOT_THREAD_SAFE TRTPrintingOfHits // Thread unsafe TRTOutputFile class is used.
 {
   public:
     TRTPrintingOfHits();
diff --git a/InnerDetector/InDetG4/TRT_G4_SD/src/TRTProcessingOfBarrelHits.h b/InnerDetector/InDetG4/TRT_G4_SD/src/TRTProcessingOfBarrelHits.h
index b6220defffb663ee6c2a38fbdc9ce856e45f2ce9..03308dd8cc8d062e474458411b5e87f3891db082 100644
--- a/InnerDetector/InDetG4/TRT_G4_SD/src/TRTProcessingOfBarrelHits.h
+++ b/InnerDetector/InDetG4/TRT_G4_SD/src/TRTProcessingOfBarrelHits.h
@@ -1,16 +1,18 @@
 /*
-  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
 #ifndef TRT_G4_SD_TRTProcessingOfBarrelHits_hh
 #define TRT_G4_SD_TRTProcessingOfBarrelHits_hh
 
+#include "CxxUtils/checker_macros.h"
+
 class TRTParameters;
 class TRTSensitiveDetector;
 
 class G4Step;
 
-class TRTProcessingOfBarrelHits
+class ATLAS_NOT_THREAD_SAFE TRTProcessingOfBarrelHits // Thread unsafe TRTParameters and TRTSensitiveDetector classes are used.
 {
   friend class TRTParametersForBarrelHits;
 
diff --git a/InnerDetector/InDetG4/TRT_G4_SD/src/TRTProcessingOfEndCapHits.h b/InnerDetector/InDetG4/TRT_G4_SD/src/TRTProcessingOfEndCapHits.h
index bf9a8559ad6874df832f968e0e25dab2ba567e59..56cc07d087dd590a70d7af673fd513b2a4b45775 100644
--- a/InnerDetector/InDetG4/TRT_G4_SD/src/TRTProcessingOfEndCapHits.h
+++ b/InnerDetector/InDetG4/TRT_G4_SD/src/TRTProcessingOfEndCapHits.h
@@ -1,16 +1,18 @@
 /*
-  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
 #ifndef TRT_G4_SD_TRTProcessingOfEndCapHits_hh
 #define TRT_G4_SD_TRTProcessingOfEndCapHits_hh
 
+#include "CxxUtils/checker_macros.h"
+
 class TRTParameters;
 class TRTSensitiveDetector;
 
 class G4Step;
 
-class TRTProcessingOfEndCapHits
+class ATLAS_NOT_THREAD_SAFE TRTProcessingOfEndCapHits // Thread unsafe TRTParameters and TRTSensitiveDetector classes are used.
 {
   friend class TRTParametersForEndCapHits;
 
diff --git a/InnerDetector/InDetG4/TRT_G4_SD/src/TRTSensitiveDetector.cxx b/InnerDetector/InDetG4/TRT_G4_SD/src/TRTSensitiveDetector.cxx
index cd207b7dfee78630e180cf01781b48217da97b66..db06ee735f9d6137200a1afc32428b43f803b477 100644
--- a/InnerDetector/InDetG4/TRT_G4_SD/src/TRTSensitiveDetector.cxx
+++ b/InnerDetector/InDetG4/TRT_G4_SD/src/TRTSensitiveDetector.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
 */
 
 
@@ -70,7 +70,7 @@ TRTSensitiveDetector::TRTSensitiveDetector(const std::string& name, const std::s
 // Called by TRTSensitiveDetector
 // Once per run
 
-void TRTSensitiveDetector::InitializeHitProcessing()
+void TRTSensitiveDetector::InitializeHitProcessing ATLAS_NOT_THREAD_SAFE () // Thread unsafe TRTParametersForBarrelHits, TRTParametersForEndCapHits  classes are used.
 {
   if(verboseLevel>4)
     {
diff --git a/InnerDetector/InDetG4/TRT_G4_SD/src/TRTSensitiveDetector.h b/InnerDetector/InDetG4/TRT_G4_SD/src/TRTSensitiveDetector.h
index f95cc4f8776b1462b42bf40f724411a93643bbc7..50dfe58d5b82849cd8f696508b615a1a72f6578e 100644
--- a/InnerDetector/InDetG4/TRT_G4_SD/src/TRTSensitiveDetector.h
+++ b/InnerDetector/InDetG4/TRT_G4_SD/src/TRTSensitiveDetector.h
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
 #ifndef TRT_G4_SD_TRTSensitiveDetector_h
@@ -8,6 +8,7 @@
 // Base class
 #include "G4VSensitiveDetector.hh"
 
+#include "CxxUtils/checker_macros.h"
 #include "InDetSimEvent/TRTUncompressedHitCollection.h"
 #include "StoreGate/WriteHandle.h"
 #include <gtest/gtest_prod.h>
@@ -15,13 +16,12 @@
 class TRTParameters;
 class TRTProcessingOfBarrelHits;
 class TRTProcessingOfEndCapHits;
-class TRTOutputFile;
 
 class G4HCofThisEvent;
 class G4Step;
 class G4TouchableHistory;
 
-class TRTSensitiveDetector : public G4VSensitiveDetector
+class ATLAS_NOT_THREAD_SAFE TRTSensitiveDetector : public G4VSensitiveDetector // Thread unsafe TRTParameters, TRTProcessingOfBarrelHits, TRTProcessingOfEndCapHits classes is used.
 {
  FRIEND_TEST( TRTSensitiveDetectortest, Initialize);
  FRIEND_TEST( TRTSensitiveDetectortest, ProcessHits );
diff --git a/InnerDetector/InDetG4/TRT_G4_SD/src/TRTSensitiveDetectorTool.cxx b/InnerDetector/InDetG4/TRT_G4_SD/src/TRTSensitiveDetectorTool.cxx
index a871c236f7a98e7cd8a677c6db142b41ac4e27e4..d2d769c6f438130aa4b98db6be7c07efe7c0c297 100644
--- a/InnerDetector/InDetG4/TRT_G4_SD/src/TRTSensitiveDetectorTool.cxx
+++ b/InnerDetector/InDetG4/TRT_G4_SD/src/TRTSensitiveDetectorTool.cxx
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
 
@@ -18,7 +18,7 @@ TRTSensitiveDetectorTool::TRTSensitiveDetectorTool(const std::string& type, cons
 
 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
 
-G4VSensitiveDetector* TRTSensitiveDetectorTool::makeSD() const
+G4VSensitiveDetector* TRTSensitiveDetectorTool::makeSD ATLAS_NOT_THREAD_SAFE () const // Thread unsafe TRTSensitiveDetector class is used.
 {
 
   ATH_MSG_DEBUG( "Initializing SD" );
diff --git a/InnerDetector/InDetG4/TRT_G4_SD/test/TRTSensitiveDetector_gtest.cxx b/InnerDetector/InDetG4/TRT_G4_SD/test/TRTSensitiveDetector_gtest.cxx
index 13033f63ac6984b4ab4f0b424187ddb0667bcead..5d54bfeb834ec49ce33922d2c7677f048bfd5e0c 100644
--- a/InnerDetector/InDetG4/TRT_G4_SD/test/TRTSensitiveDetector_gtest.cxx
+++ b/InnerDetector/InDetG4/TRT_G4_SD/test/TRTSensitiveDetector_gtest.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
 */
 
 #include "src/TRTSensitiveDetector.h"
@@ -32,6 +32,8 @@
 #include "G4AtlasTools/DerivedG4SensitiveDetectorTestSetting.h"
 #include "MCTruth/TrackHelper.h"
 
+ATLAS_NO_CHECK_FILE_THREAD_SAFETY; // Thread unsafe TRTSensitiveDetector class is tested in this unit test.
+
 //set environment
 class GaudiEnvironment : public ::testing::Environment {
   protected: