Fixes for image

changedetectionio/__init__.py

@@ -41,9 +41,10 @@ from loguru import logger
 #
 # IMPLEMENTATION:
 #   1. Explicit contexts everywhere (primary protection):
-#      - Watch.py: ctx = multiprocessing.get_context('spawn')
 #      - playwright.py: ctx = multiprocessing.get_context('spawn')
 #      - puppeteer.py: ctx = multiprocessing.get_context('spawn')
+#      - isolated_opencv.py: ctx = multiprocessing.get_context('spawn')
+#      - isolated_libvips.py: ctx = multiprocessing.get_context('spawn')
 #
 #   2. Global default (defense-in-depth, below):
 #      - Safety net if future code forgets explicit context

changedetectionio/model/Watch.py

@@ -18,21 +18,31 @@ BROTLI_COMPRESS_SIZE_THRESHOLD = int(os.getenv('SNAPSHOT_BROTLI_COMPRESSION_THRE
 minimum_seconds_recheck_time = int(os.getenv('MINIMUM_SECONDS_RECHECK_TIME', 3))
 mtable = {'seconds': 1, 'minutes': 60, 'hours': 3600, 'days': 86400, 'weeks': 86400 * 7}
 
-def _brotli_compress_worker(conn, filepath, mode=None):
+def _brotli_save(contents, filepath, mode=None, fallback_uncompressed=False):
     """
-    Worker function to compress data with brotli in a separate process.
-    This isolates memory - when process exits, OS reclaims all memory.
+    Save compressed data using native brotli.
+    Testing shows no memory leak when using gc.collect() after compression.
 
     Args:
-        conn: multiprocessing.Pipe connection to receive data
+        contents: data to compress (str or bytes)
         filepath: destination file path
         mode: brotli compression mode (e.g., brotli.MODE_TEXT)
+        fallback_uncompressed: if True, save uncompressed on failure; if False, raise exception
+
+    Returns:
+        str: actual filepath saved (may differ from input if fallback used)
+
+    Raises:
+        Exception: if compression fails and fallback_uncompressed is False
     """
     import brotli
+    import gc
+
+    # Ensure contents are bytes
+    if isinstance(contents, str):
+        contents = contents.encode('utf-8')
 
     try:
-        # Receive data from parent process via pipe (avoids pickle overhead)
-        contents = conn.recv()
         logger.debug(f"Starting brotli compression of {len(contents)} bytes.")
 
         if mode is not None:
@@ -43,111 +53,25 @@ def _brotli_compress_worker(conn, filepath, mode=None):
         with open(filepath, 'wb') as f:
             f.write(compressed_data)
 
-        # Send success status back
-        conn.send(True)
         logger.debug(f"Finished brotli compression - From {len(contents)} to {len(compressed_data)} bytes.")
-        # No need for explicit cleanup - process exit frees all memory
-    except Exception as e:
-        logger.critical(f"Brotli compression worker failed: {e}")
-        conn.send(False)
-    finally:
-        conn.close()
 
+        # Force garbage collection to prevent memory buildup
+        gc.collect()
 
-def _brotli_subprocess_save(contents, filepath, mode=None, timeout=30, fallback_uncompressed=False):
-    """
-    Save compressed data using subprocess to isolate memory.
-    Uses Pipe to avoid pickle overhead for large data.
-
-    Args:
-        contents: data to compress (str or bytes)
-        filepath: destination file path
-        mode: brotli compression mode (e.g., brotli.MODE_TEXT)
-        timeout: subprocess timeout in seconds
-        fallback_uncompressed: if True, save uncompressed on failure; if False, raise exception
-
-    Returns:
-        str: actual filepath saved (may differ from input if fallback used)
-
-    Raises:
-        Exception: if compression fails and fallback_uncompressed is False
-    """
-    import multiprocessing
-    import sys
-
-    # Ensure contents are bytes
-    if isinstance(contents, str):
-        contents = contents.encode('utf-8')
-
-    # Use explicit spawn context for thread safety (avoids fork() with multi-threaded parent)
-    # Always use spawn - consistent behavior in tests and production
-    ctx = multiprocessing.get_context('spawn')
-    parent_conn, child_conn = ctx.Pipe()
-
-    # Run compression in subprocess using spawn (not fork)
-    proc = ctx.Process(target=_brotli_compress_worker, args=(child_conn, filepath, mode))
-
-    # Windows-safe: Set daemon=False explicitly to avoid issues with process cleanup
-    proc.daemon = False
-    proc.start()
-
-    try:
-        # Send data to subprocess via pipe (avoids pickle)
-        parent_conn.send(contents)
-
-        # Wait for result with timeout
-        if parent_conn.poll(timeout):
-            success = parent_conn.recv()
-        else:
-            success = False
-            logger.warning(f"Brotli compression subprocess timed out after {timeout}s")
-            # Graceful termination with platform-aware cleanup
-            try:
-                proc.terminate()
-            except Exception as term_error:
-                logger.debug(f"Process termination issue (may be normal on Windows): {term_error}")
-
-        parent_conn.close()
-        proc.join(timeout=5)
-
-        # Force kill if still alive after graceful termination
-        if proc.is_alive():
-            try:
-                if sys.platform == 'win32':
-                    # Windows: use kill() which is more forceful
-                    proc.kill()
-                else:
-                    # Unix: terminate() already sent SIGTERM, now try SIGKILL
-                    proc.kill()
-                proc.join(timeout=2)
-            except Exception as kill_error:
-                logger.warning(f"Failed to kill brotli compression process: {kill_error}")
-
-        # Check if file was created successfully
-        if success and os.path.exists(filepath):
-            return filepath
+        return filepath
 
     except Exception as e:
         logger.error(f"Brotli compression error: {e}")
-        try:
-            parent_conn.close()
-        except:
-            pass
-        try:
-            proc.terminate()
-            proc.join(timeout=2)
-        except:
-            pass
 
-    # Compression failed
-    if fallback_uncompressed:
-        logger.warning(f"Brotli compression failed for {filepath}, saving uncompressed")
-        fallback_path = filepath.replace('.br', '')
-        with open(fallback_path, 'wb') as f:
-            f.write(contents)
-        return fallback_path
-    else:
-        raise Exception(f"Brotli compression subprocess failed for {filepath}")
+        # Compression failed
+        if fallback_uncompressed:
+            logger.warning(f"Brotli compression failed for {filepath}, saving uncompressed")
+            fallback_path = filepath.replace('.br', '')
+            with open(fallback_path, 'wb') as f:
+                f.write(contents)
+            return fallback_path
+        else:
+            raise Exception(f"Brotli compression failed for {filepath}: {e}")
 
 
 class model(watch_base):
@@ -523,7 +447,7 @@ class model(watch_base):
 
                 if not os.path.exists(dest):
                     try:
-                        actual_dest = _brotli_subprocess_save(contents, dest, mode=brotli.MODE_TEXT, fallback_uncompressed=True)
+                        actual_dest = _brotli_save(contents, dest, mode=brotli.MODE_TEXT, fallback_uncompressed=True)
                         if actual_dest != dest:
                             snapshot_fname = os.path.basename(actual_dest)
                     except Exception as e:
@@ -949,13 +873,13 @@ class model(watch_base):
     def save_last_text_fetched_before_filters(self, contents):
         import brotli
         filepath = os.path.join(self.watch_data_dir, 'last-fetched.br')
-        _brotli_subprocess_save(contents, filepath, mode=brotli.MODE_TEXT, fallback_uncompressed=False)
+        _brotli_save(contents, filepath, mode=brotli.MODE_TEXT, fallback_uncompressed=False)
 
     def save_last_fetched_html(self, timestamp, contents):
         self.ensure_data_dir_exists()
         snapshot_fname = f"{timestamp}.html.br"
         filepath = os.path.join(self.watch_data_dir, snapshot_fname)
-        _brotli_subprocess_save(contents, filepath, mode=None, fallback_uncompressed=True)
+        _brotli_save(contents, filepath, mode=None, fallback_uncompressed=True)
         self._prune_last_fetched_html_snapshots()
 
     def get_fetched_html(self, timestamp):

changedetectionio/processors/image_ssim_diff/image_handler/isolated_libvips.py

@@ -13,14 +13,9 @@ Research: https://github.com/libvips/pyvips/issues/234
 
 import multiprocessing
 
-# CRITICAL: Use 'spawn' instead of 'fork' to avoid inheriting parent's
+# CRITICAL: Use 'spawn' context instead of 'fork' to avoid inheriting parent's
 # LibVIPS threading state which can cause hangs in gaussblur operations
 # https://docs.python.org/3/library/multiprocessing.html#contexts-and-start-methods
-try:
-    multiprocessing.set_start_method('spawn', force=False)
-except RuntimeError:
-    # Already set, ignore
-    pass
 
 
 def _worker_generate_diff(conn, img_bytes_from, img_bytes_to, threshold, blur_sigma, max_width, max_height):
@@ -95,9 +90,10 @@ def generate_diff_isolated(img_bytes_from, img_bytes_to, threshold, blur_sigma,
     Returns:
         bytes: JPEG diff image or None on failure
     """
-    parent_conn, child_conn = multiprocessing.Pipe()
+    ctx = multiprocessing.get_context('spawn')
+    parent_conn, child_conn = ctx.Pipe()
 
-    p = multiprocessing.Process(
+    p = ctx.Process(
         target=_worker_generate_diff,
         args=(child_conn, img_bytes_from, img_bytes_to, threshold, blur_sigma, max_width, max_height)
     )
@@ -140,7 +136,8 @@ def calculate_change_percentage_isolated(img_bytes_from, img_bytes_to, threshold
     Returns:
         float: Change percentage
     """
-    parent_conn, child_conn = multiprocessing.Pipe()
+    ctx = multiprocessing.get_context('spawn')
+    parent_conn, child_conn = ctx.Pipe()
 
     def _worker_calculate(conn):
         try:
@@ -185,7 +182,7 @@ def calculate_change_percentage_isolated(img_bytes_from, img_bytes_to, threshold
         finally:
             conn.close()
 
-    p = multiprocessing.Process(target=_worker_calculate, args=(child_conn,))
+    p = ctx.Process(target=_worker_calculate, args=(child_conn,))
     p.start()
 
     result = 0.0
@@ -233,7 +230,8 @@ def compare_images_isolated(img_bytes_from, img_bytes_to, threshold, blur_sigma,
         tuple: (changed_detected, change_percentage)
     """
     print(f"[Parent] Starting compare_images_isolated subprocess", flush=True)
-    parent_conn, child_conn = multiprocessing.Pipe()
+    ctx = multiprocessing.get_context('spawn')
+    parent_conn, child_conn = ctx.Pipe()
 
     def _worker_compare(conn):
         try:
@@ -301,7 +299,7 @@ def compare_images_isolated(img_bytes_from, img_bytes_to, threshold, blur_sigma,
         finally:
             conn.close()
 
-    p = multiprocessing.Process(target=_worker_compare, args=(child_conn,))
+    p = ctx.Process(target=_worker_compare, args=(child_conn,))
     print(f"[Parent] Starting subprocess (pid will be assigned)", flush=True)
     p.start()
     print(f"[Parent] Subprocess started (pid={p.pid}), waiting for result (30s timeout)", flush=True)