debugging NF4 loader issue and sequence loading in general.

Have a method that works, broke it, so re-assembling it slowly.

This is the initial commit where N4 is importint correctly.

__init__.py

@@ -2,8 +2,42 @@ import time
 import copy
 import torch
 import comfy.model_management
+import logging
+# Add these two new imports:
+import os
+import importlib.util
+
+# Setup basic logging
+logging.basicConfig(level=logging.INFO, format='%(asctime)s - %(levelname)s - %(message)s')
+
+logging.info("DEBUG: MultiGPU node initialization started.")
+
+def import_nf4_classes():
+    try:
+        nf4_path = os.path.join("custom_nodes", "ComfyUI_bnb_nf4_fp4_Loaders", "__init__.py")
+        logging.info(f"DEBUG: Attempting to pre-load NF4 classes from {nf4_path}")
+        
+        if not os.path.exists(nf4_path):
+            logging.info("DEBUG: NF4 loader path does not exist")
+            return None, None
+            
+        spec = importlib.util.spec_from_file_location("nf4_loaders", nf4_path)
+        nf4_module = importlib.util.module_from_spec(spec)
+        spec.loader.exec_module(nf4_module)
+        logging.info("DEBUG: Successfully pre-loaded NF4 classes")
+        return nf4_module.CheckpointLoaderNF4, nf4_module.UNETLoaderNF4
+    except Exception as e:
+        logging.info(f"DEBUG: Failed to pre-load NF4 classes: {str(e)}")
+        return None, None
+
+
+# Try to get NF4 classes early
+logging.info("DEBUG: Attempting early NF4 class import")
+CheckpointLoaderNF4, UNETLoaderNF4 = import_nf4_classes()
+logging.info(f"DEBUG: Early NF4 import result - CheckpointLoader: {'Found' if CheckpointLoaderNF4 else 'Not Found'}, UNETLoader: {'Found' if UNETLoaderNF4 else 'Not Found'}")
 
 current_device = comfy.model_management.get_torch_device()
+logging.info(f"DEBUG: Initial device: {current_device}")
 
 def get_torch_device_patched():
     if (
@@ -11,7 +45,9 @@ def get_torch_device_patched():
         or comfy.model_management.cpu_state == comfy.model_management.CPUState.CPU
         or "cpu" in str(current_device).lower()
     ):
+        logging.info("DEBUG: get_torch_device_patched returning CPU.")
         return torch.device("cpu")
+    logging.info(f"DEBUG: get_torch_device_patched returning current_device: {current_device}")
     return torch.device(current_device)
 
 comfy.model_management.get_torch_device = get_torch_device_patched
@@ -29,15 +65,22 @@ def override_class(cls):
         FUNCTION = "override"
 
         def override(self, *args, device, **kwargs):
+            logging.info(f"DEBUG: Overriding node '{cls.__name__}' with device: {device}")
             global current_device
+            logging.info(f"DEBUG: Current device before override: {current_device}")
             current_device = device
+            logging.info(f"DEBUG: Current device after override: {current_device}")
             fn = getattr(super(), cls.FUNCTION)
             return fn(*args, **kwargs)
 
     return NodeOverride
 
-time.sleep(2) # This is to make sure the other nodes are already loaded
+logging.info("DEBUG: Sleeping for 20 seconds to allow other nodes to load.")
+time.sleep(20) # This is to make sure the other nodes are already loaded
 from nodes import NODE_CLASS_MAPPINGS as GLOBAL_NODE_CLASS_MAPPINGS
+logging.info("DEBUG: GLOBAL_NODE_CLASS_MAPPINGS after sleep:")
+for key in GLOBAL_NODE_CLASS_MAPPINGS:
+    logging.info(f"DEBUG:   {key}")
 
 TARGET_NODE_NAMES = {
     "UNETLoader", "VAELoader", "CLIPLoader", "DualCLIPLoader", "TripleCLIPLoader", "CheckpointLoaderSimple", "ControlNetLoader",            # ComfyUI Core Nodes - https://github.com/comfyanonymous/ComfyUI
@@ -46,10 +89,26 @@ TARGET_NODE_NAMES = {
     "Florence2ModelLoader", "DownloadAndLoadFlorence2Model",                                                                                # ComfyUI-Florence2 - https://github.com/kijai/ComfyUI-Florence2
     "LTXVLoader",                                                                                                                           # ComfyUI-LTXVideo - https://github.com/Lightricks/ComfyUI-LTXVideo
     "MMAudioFeatureUtilsLoader", "MMAudioModelLoader", "MMAudioSampler",                                                                    # ComfyUI-MMAudio - https://github.com/kijai/ComfyUI-MMAudio --EXPERIMENTAL--
+    "CheckpointLoaderNF4",
 }
 
 NODE_CLASS_MAPPINGS = {}
 for name in TARGET_NODE_NAMES:
-    if name not in GLOBAL_NODE_CLASS_MAPPINGS:
-        continue
-    NODE_CLASS_MAPPINGS[f"{name}MultiGPU"] = override_class(GLOBAL_NODE_CLASS_MAPPINGS[name])
+    logging.info(f"DEBUG: Checking for '{name}' in GLOBAL_NODE_CLASS_MAPPINGS...")
+    if name in GLOBAL_NODE_CLASS_MAPPINGS:
+        original_class = GLOBAL_NODE_CLASS_MAPPINGS[name]
+        NODE_CLASS_MAPPINGS[f"{name}MultiGPU"] = override_class(original_class)
+        logging.info(f"DEBUG: Successfully created MultiGPU version for '{name}'.")
+    else:
+        logging.warning(f"DEBUG: Node '{name}' not found in GLOBAL_NODE_CLASS_MAPPINGS.")
+
+# Add the NF4 nodes if they were loaded
+if CheckpointLoaderNF4 is not None:
+    logging.info("DEBUG: Adding pre-loaded CheckpointLoaderNF4 to MultiGPU nodes")
+    NODE_CLASS_MAPPINGS["CheckpointLoaderNF4MultiGPU"] = override_class(CheckpointLoaderNF4)
+
+if UNETLoaderNF4 is not None:
+    logging.info("DEBUG: Adding pre-loaded UNETLoaderNF4 to MultiGPU nodes")
+    NODE_CLASS_MAPPINGS["UNETLoaderNF4MultiGPU"] = override_class(UNETLoaderNF4)
+
+logging.info("DEBUG: MultiGPU node initialization completed.")