fix

model_training_nnn_tpu/trainer_tf.py

@@ -102,18 +102,25 @@ class BrainToTextDecoderTrainerTF:
             try:
                 # Check if strategy is properly initialized before applying gradients
                 if hasattr(self.strategy, 'merge_call') and callable(getattr(self.strategy, 'merge_call')):
+                    print("✅ Strategy has merge_call, building optimizer properly...")
+
+                    # Build optimizer by explicitly calling build method
+                    self.optimizer.build(self.model.trainable_variables)
+                    print("✅ Optimizer built with model variables")
+
+                    # Test with dummy gradients to ensure everything works
                     dummy_grads = [tf.zeros_like(w) for w in self.model.trainable_variables]
                     self.optimizer.apply_gradients(zip(dummy_grads, self.model.trainable_variables))
                     print("✅ Optimizer state pre-built successfully with TPU strategy")
                 else:
                     # Fallback: just build optimizer variables without applying gradients
-                    print("⚠️  Strategy not fully initialized, skipping optimizer pre-build")
-                    # Alternative: trigger optimizer variable creation
-                    _ = self.optimizer.iterations
-                    print("✅ Optimizer state initialized (fallback mode)")
+                    print("⚠️  Strategy not fully initialized, using fallback optimizer build")
+                    # Force build the optimizer with the model variables
+                    self.optimizer.build(self.model.trainable_variables)
+                    print("✅ Optimizer built in fallback mode")
             except Exception as e:
                 print(f"⚠️  Warning: Could not pre-build optimizer state: {e}")
-                print("✅ Continuing without optimizer pre-build")
+                print("✅ Continuing without optimizer pre-build - optimizer will build during first training step")
 
             print("📅 Setting up learning rate scheduler...")
             self.lr_scheduler = self._create_lr_scheduler()
@@ -414,6 +421,9 @@ class BrainToTextDecoderTrainerTF:
         """Create AdamW optimizer with parameter groups"""
         # Note: TensorFlow doesn't have the same parameter group functionality as PyTorch
         # We'll use a single optimizer and handle different learning rates in the scheduler
+
+        # Create optimizer within strategy scope to ensure proper initialization
+        print(f"Creating optimizer with strategy: {type(self.strategy).__name__}")
         optimizer = tf.keras.optimizers.AdamW(
             learning_rate=self.args['lr_max'],
             beta_1=self.args['beta0'],
@@ -565,7 +575,18 @@ class BrainToTextDecoderTrainerTF:
 
         # Apply gradients (only for variables that have gradients)
         if len(filtered_gradients) > 0:
+            # Ensure we're in the strategy scope when applying gradients
+            # This prevents the 'NoneType' extended attribute error
+            try:
                 self.optimizer.apply_gradients(zip(filtered_gradients, filtered_variables))
+            except AttributeError as e:
+                if "'NoneType' object has no attribute 'extended'" in str(e):
+                    # Strategy context was lost, this should not happen in a @tf.function
+                    tf.print(f"ERROR: Strategy context lost during gradient application: {e}")
+                    tf.print("This indicates a serious issue with the distributed training setup")
+                    raise RuntimeError(f"Strategy context lost during training: {e}")
+                else:
+                    raise
 
         return loss, grad_norm