diff --git a/engines/ml/lightgbm/src/main/java/ai/djl/ml/lightgbm/LgbmEngineProvider.java b/engines/ml/lightgbm/src/main/java/ai/djl/ml/lightgbm/LgbmEngineProvider.java
index a253ce3d246..f8c84c753ef 100644
--- a/engines/ml/lightgbm/src/main/java/ai/djl/ml/lightgbm/LgbmEngineProvider.java
+++ b/engines/ml/lightgbm/src/main/java/ai/djl/ml/lightgbm/LgbmEngineProvider.java
@@ -18,8 +18,6 @@
 /** {@code LgbmEngineProvider} is the LightGBM implementation of {@link EngineProvider}. */
 public class LgbmEngineProvider implements EngineProvider {
 
-    private static volatile Engine engine; // NOPMD
-
     /** {@inheritDoc} */
     @Override
     public String getEngineName() {
@@ -35,11 +33,10 @@ public int getEngineRank() {
     /** {@inheritDoc} */
     @Override
     public Engine getEngine() {
-        if (engine == null) {
-            synchronized (LgbmEngineProvider.class) {
-                engine = LgbmEngine.newInstance();
-            }
-        }
-        return engine;
+        return InstanceHolder.INSTANCE;
+    }
+
+    private static class InstanceHolder {
+        static final Engine INSTANCE = LgbmEngine.newInstance();
     }
 }
diff --git a/engines/ml/xgboost/src/main/java/ai/djl/ml/xgboost/XgbEngineProvider.java b/engines/ml/xgboost/src/main/java/ai/djl/ml/xgboost/XgbEngineProvider.java
index 19cba32cc71..5859f3f344d 100644
--- a/engines/ml/xgboost/src/main/java/ai/djl/ml/xgboost/XgbEngineProvider.java
+++ b/engines/ml/xgboost/src/main/java/ai/djl/ml/xgboost/XgbEngineProvider.java
@@ -18,8 +18,6 @@
 /** {@code XgbEngineProvider} is the XGBoost implementation of {@link EngineProvider}. */
 public class XgbEngineProvider implements EngineProvider {
 
-    private static volatile Engine engine; // NOPMD
-
     /** {@inheritDoc} */
     @Override
     public String getEngineName() {
@@ -35,11 +33,10 @@ public int getEngineRank() {
     /** {@inheritDoc} */
     @Override
     public Engine getEngine() {
-        if (engine == null) {
-            synchronized (XgbEngineProvider.class) {
-                engine = XgbEngine.newInstance();
-            }
-        }
-        return engine;
+        return InstanceHolder.INSTANCE;
+    }
+
+    private static class InstanceHolder {
+        static final Engine INSTANCE = XgbEngine.newInstance();
     }
 }
diff --git a/engines/mxnet/mxnet-engine/src/main/java/ai/djl/mxnet/engine/MxEngineProvider.java b/engines/mxnet/mxnet-engine/src/main/java/ai/djl/mxnet/engine/MxEngineProvider.java
index f30a6a89252..5f45116f615 100644
--- a/engines/mxnet/mxnet-engine/src/main/java/ai/djl/mxnet/engine/MxEngineProvider.java
+++ b/engines/mxnet/mxnet-engine/src/main/java/ai/djl/mxnet/engine/MxEngineProvider.java
@@ -18,8 +18,6 @@
 /** {@code MxEngineProvider} is the MXNet implementation of {@link EngineProvider}. */
 public class MxEngineProvider implements EngineProvider {
 
-    private static volatile Engine engine; // NOPMD
-
     /** {@inheritDoc} */
     @Override
     public String getEngineName() {
@@ -35,11 +33,10 @@ public int getEngineRank() {
     /** {@inheritDoc} */
     @Override
     public Engine getEngine() {
-        if (engine == null) {
-            synchronized (MxEngineProvider.class) {
-                engine = MxEngine.newInstance();
-            }
-        }
-        return engine;
+        return InstanceHolder.INSTANCE;
+    }
+
+    private static class InstanceHolder {
+        static final Engine INSTANCE = MxEngine.newInstance();
     }
 }
diff --git a/engines/onnxruntime/onnxruntime-engine/src/main/java/ai/djl/onnxruntime/engine/OrtEngineProvider.java b/engines/onnxruntime/onnxruntime-engine/src/main/java/ai/djl/onnxruntime/engine/OrtEngineProvider.java
index c673b3dcbf1..005c0fa25f1 100644
--- a/engines/onnxruntime/onnxruntime-engine/src/main/java/ai/djl/onnxruntime/engine/OrtEngineProvider.java
+++ b/engines/onnxruntime/onnxruntime-engine/src/main/java/ai/djl/onnxruntime/engine/OrtEngineProvider.java
@@ -18,8 +18,6 @@
 /** {@code OrtEngineProvider} is the ONNX Runtime implementation of {@link EngineProvider}. */
 public class OrtEngineProvider implements EngineProvider {
 
-    private static volatile Engine engine; // NOPMD
-
     /** {@inheritDoc} */
     @Override
     public String getEngineName() {
@@ -35,11 +33,10 @@ public int getEngineRank() {
     /** {@inheritDoc} */
     @Override
     public Engine getEngine() {
-        if (engine == null) {
-            synchronized (OrtEngineProvider.class) {
-                engine = OrtEngine.newInstance();
-            }
-        }
-        return engine;
+        return InstanceHolder.INSTANCE;
+    }
+
+    private static class InstanceHolder {
+        static final Engine INSTANCE = OrtEngine.newInstance();
     }
 }
diff --git a/engines/paddlepaddle/paddlepaddle-engine/src/main/java/ai/djl/paddlepaddle/engine/PpEngineProvider.java b/engines/paddlepaddle/paddlepaddle-engine/src/main/java/ai/djl/paddlepaddle/engine/PpEngineProvider.java
index e2b5bdd35a0..59e5cd90724 100644
--- a/engines/paddlepaddle/paddlepaddle-engine/src/main/java/ai/djl/paddlepaddle/engine/PpEngineProvider.java
+++ b/engines/paddlepaddle/paddlepaddle-engine/src/main/java/ai/djl/paddlepaddle/engine/PpEngineProvider.java
@@ -18,8 +18,6 @@
 /** {@code PpEngineProvider} is the PaddlePaddle implementation of {@link EngineProvider}. */
 public class PpEngineProvider implements EngineProvider {
 
-    private static volatile Engine engine; // NOPMD
-
     /** {@inheritDoc} */
     @Override
     public String getEngineName() {
@@ -35,11 +33,10 @@ public int getEngineRank() {
     /** {@inheritDoc} */
     @Override
     public Engine getEngine() {
-        if (engine == null) {
-            synchronized (PpEngineProvider.class) {
-                engine = PpEngine.newInstance();
-            }
-        }
-        return engine;
+        return InstanceHolder.INSTANCE;
+    }
+
+    private static class InstanceHolder {
+        static final Engine INSTANCE = PpEngine.newInstance();
     }
 }
diff --git a/engines/pytorch/pytorch-engine/src/main/java/ai/djl/pytorch/engine/PtEngineProvider.java b/engines/pytorch/pytorch-engine/src/main/java/ai/djl/pytorch/engine/PtEngineProvider.java
index 57ae6c09d34..1b9cdd0ab19 100644
--- a/engines/pytorch/pytorch-engine/src/main/java/ai/djl/pytorch/engine/PtEngineProvider.java
+++ b/engines/pytorch/pytorch-engine/src/main/java/ai/djl/pytorch/engine/PtEngineProvider.java
@@ -18,8 +18,6 @@
 /** {@code PtEngineProvider} is the PyTorch implementation of {@link EngineProvider}. */
 public class PtEngineProvider implements EngineProvider {
 
-    private static volatile Engine engine; // NOPMD
-
     /** {@inheritDoc} */
     @Override
     public String getEngineName() {
@@ -35,11 +33,10 @@ public int getEngineRank() {
     /** {@inheritDoc} */
     @Override
     public Engine getEngine() {
-        if (engine == null) {
-            synchronized (PtEngineProvider.class) {
-                engine = PtEngine.newInstance();
-            }
-        }
-        return engine;
+        return InstanceHolder.INSTANCE;
+    }
+
+    private static class InstanceHolder {
+        static final Engine INSTANCE = PtEngine.newInstance();
     }
 }
diff --git a/engines/tensorflow/tensorflow-engine/src/main/java/ai/djl/tensorflow/engine/TfEngineProvider.java b/engines/tensorflow/tensorflow-engine/src/main/java/ai/djl/tensorflow/engine/TfEngineProvider.java
index d964ea5c295..f42f691d222 100644
--- a/engines/tensorflow/tensorflow-engine/src/main/java/ai/djl/tensorflow/engine/TfEngineProvider.java
+++ b/engines/tensorflow/tensorflow-engine/src/main/java/ai/djl/tensorflow/engine/TfEngineProvider.java
@@ -18,8 +18,6 @@
 /** {@code TfEngineProvider} is the TensorFlow implementation of {@link EngineProvider}. */
 public class TfEngineProvider implements EngineProvider {
 
-    private static volatile Engine engine; // NOPMD
-
     /** {@inheritDoc} */
     @Override
     public String getEngineName() {
@@ -35,11 +33,10 @@ public int getEngineRank() {
     /** {@inheritDoc} */
     @Override
     public Engine getEngine() {
-        if (engine == null) {
-            synchronized (TfEngineProvider.class) {
-                engine = TfEngine.newInstance();
-            }
-        }
-        return engine;
+        return InstanceHolder.INSTANCE;
+    }
+
+    private static class InstanceHolder {
+        static final Engine INSTANCE = TfEngine.newInstance();
     }
 }
diff --git a/engines/tensorrt/src/main/java/ai/djl/tensorrt/engine/TrtEngineProvider.java b/engines/tensorrt/src/main/java/ai/djl/tensorrt/engine/TrtEngineProvider.java
index 05a7eceeb41..d92ed9e449d 100644
--- a/engines/tensorrt/src/main/java/ai/djl/tensorrt/engine/TrtEngineProvider.java
+++ b/engines/tensorrt/src/main/java/ai/djl/tensorrt/engine/TrtEngineProvider.java
@@ -18,8 +18,6 @@
 /** {@code TrtEngineProvider} is the TensorRT implementation of {@link EngineProvider}. */
 public class TrtEngineProvider implements EngineProvider {
 
-    private static volatile Engine engine; // NOPMD
-
     /** {@inheritDoc} */
     @Override
     public String getEngineName() {
@@ -35,11 +33,10 @@ public int getEngineRank() {
     /** {@inheritDoc} */
     @Override
     public Engine getEngine() {
-        if (engine == null) {
-            synchronized (TrtEngineProvider.class) {
-                engine = TrtEngine.newInstance();
-            }
-        }
-        return engine;
+        return InstanceHolder.INSTANCE;
+    }
+
+    private static class InstanceHolder {
+        static final Engine INSTANCE = TrtEngine.newInstance();
     }
 }
diff --git a/engines/tflite/tflite-engine/src/main/java/ai/djl/tflite/engine/TfLiteEngineProvider.java b/engines/tflite/tflite-engine/src/main/java/ai/djl/tflite/engine/TfLiteEngineProvider.java
index aa0fdb73d21..fb61551a3bf 100644
--- a/engines/tflite/tflite-engine/src/main/java/ai/djl/tflite/engine/TfLiteEngineProvider.java
+++ b/engines/tflite/tflite-engine/src/main/java/ai/djl/tflite/engine/TfLiteEngineProvider.java
@@ -18,8 +18,6 @@
 /** {@code TfLiteEngineProvider} is the TFLite implementation of {@link EngineProvider}. */
 public class TfLiteEngineProvider implements EngineProvider {
 
-    private static volatile Engine engine; // NOPMD
-
     /** {@inheritDoc} */
     @Override
     public String getEngineName() {
@@ -35,11 +33,10 @@ public int getEngineRank() {
     /** {@inheritDoc} */
     @Override
     public Engine getEngine() {
-        if (engine == null) {
-            synchronized (TfLiteEngineProvider.class) {
-                engine = TfLiteEngine.newInstance();
-            }
-        }
-        return engine;
+        return InstanceHolder.INSTANCE;
+    }
+
+    private static class InstanceHolder {
+        static final Engine INSTANCE = TfLiteEngine.newInstance();
     }
 }