Fix daemon process multiprocessing by using spawn method

- Set multiprocessing start method to 'spawn' at module level
- This allows multiprocessing to work in daemon environments like HuggingFace Spaces
- Fixes 'daemonic processes are not allowed to have children' error
- Maintains process isolation for OpenMP safety and crash protection
- Restores proper background removal with alpha matting support

hy3dshape/hy3dshape/rembg.py

@@ -24,6 +24,13 @@ os.environ["PYTHONFAULTHANDLER"] = "1"  # Better error reporting
 os.environ["KMP_DUPLICATE_LIB_OK"] = "TRUE"  # Avoid Intel MKL errors
 os.environ["OMP_THREAD_LIMIT"] = "1"  # Limit total number of OpenMP threads
 
+# Fix daemon process multiprocessing by using spawn instead of fork
+try:
+    multiprocessing.set_start_method('spawn', force=True)
+    print("Set multiprocessing start method to 'spawn' for daemon compatibility")
+except RuntimeError as e:
+    print(f"Could not set multiprocessing start method: {e}")
+
 from PIL import Image
 from rembg import remove, new_session
 
@@ -71,21 +78,11 @@ def _remove_bg_in_process(image_bytes, use_alpha_matting=True):
 
 class BackgroundRemover():
     def __init__(self):
-        # Set multiprocessing start method to 'spawn' to avoid OpenMP fork issues
-        # Only set if not already set
-        current_method = multiprocessing.get_start_method(allow_none=True)
-        if current_method != 'spawn':
-            try:
-                multiprocessing.set_start_method('spawn', force=True)
-                print(f"Set multiprocessing start method to 'spawn' (was: {current_method})")
-            except RuntimeError as e:
-                # If already set and not 'spawn', we'll have to work with what we have
-                print(f"Warning: Could not set multiprocessing start method to 'spawn': {e}")
-                print(f"Current method: {multiprocessing.get_start_method()}")
-        
-        # We don't initialize the session here anymore as it will be created in the subprocess
-        self.session = None
-        self.max_retries = 2  # Maximum number of retries for background removal
+        # Initialize background remover with multiprocessing using spawn method
+        # OpenMP conflicts are handled by environment variables and process isolation
+        print("Initializing BackgroundRemover with multiprocessing (spawn method)")
+        self.session = None  # Session will be created in subprocess
+        self.max_retries = 2
 
     def __call__(self, image: Image.Image):
         if not isinstance(image, Image.Image):
@@ -105,25 +102,22 @@ class BackgroundRemover():
             if image.mode != 'RGBA':
                 image = image.convert('RGBA')
             
+            print("Starting background removal with multiprocessing (spawn method)...")
+            
             # Convert image to bytes for passing to subprocess
             img_bytes = io.BytesIO()
             image.save(img_bytes, format='PNG')
             img_bytes = img_bytes.getvalue()
             
-            # Create a process context
-            try:
-                ctx = multiprocessing.get_context('spawn')
-            except RuntimeError:
-                # Fallback to default context if spawn is not available
-                ctx = multiprocessing
-            
             # Try with alpha matting first (high quality)
+            print("Attempting alpha matting background removal...")
             for attempt in range(self.max_retries):
                 try:
-                    with ctx.Pool(processes=1) as pool:
+                    with multiprocessing.Pool(processes=1) as pool:
                         result = pool.apply(_remove_bg_in_process, args=(img_bytes, True))
                     
                     if result is not None:
+                        print("Alpha matting successful")
                         return Image.open(io.BytesIO(result))
                     break  # Exit retry loop if we got a result (even if None)
                 except Exception as e:
@@ -135,10 +129,11 @@ class BackgroundRemover():
             print("Alpha matting failed, falling back to standard background removal")
             for attempt in range(self.max_retries):
                 try:
-                    with ctx.Pool(processes=1) as pool:
+                    with multiprocessing.Pool(processes=1) as pool:
                         result = pool.apply(_remove_bg_in_process, args=(img_bytes, False))
                     
                     if result is not None:
+                        print("Standard background removal successful")
                         return Image.open(io.BytesIO(result))
                     break  # Exit retry loop if we got a result (even if None)
                 except Exception as e: