From 1ceacd71e36e1f7a1add0d95f128b77641c11521 Mon Sep 17 00:00:00 2001
From: Josh Hawkins <32435876+hawkeye217@users.noreply.github.com>
Date: Thu, 21 May 2026 17:11:55 -0500
Subject: [PATCH] drop stale shm cache refs when cached segment is too small
 for requested shape

---
 frigate/util/image.py | 28 +++++++++++++++++++++++++---
 1 file changed, 25 insertions(+), 3 deletions(-)

diff --git a/frigate/util/image.py b/frigate/util/image.py
index 2d2133c6b8..4054c54182 100644
--- a/frigate/util/image.py
+++ b/frigate/util/image.py
@@ -1089,10 +1089,32 @@ class SharedMemoryFrameManager(FrameManager):
 
     def get(self, name: str, shape) -> Optional[np.ndarray]:
         try:
-            if name in self.shm_store:
-                shm = self.shm_store[name]
-            else:
+            required = int(np.prod(shape))
+            shm = self.shm_store.get(name)
+            if shm is not None and shm.size < required:
+                # Cached reference points at an older, smaller segment
+                # that was unlinked and recreated at a larger size in a
+                # camera add/remove cycle. Drop the stale ref so we
+                # reopen the current segment.
+                try:
+                    shm.close()
+                except Exception:
+                    pass
+                self.shm_store.pop(name, None)
+                shm = None
+            if shm is None:
                 shm = UntrackedSharedMemory(name=name)
+                if shm.size < required:
+                    # Transient mid-recreate state: the OS-level segment
+                    # is still at the previous (smaller) size because the
+                    # maintainer hasn't allocated the new one yet. Don't
+                    # cache it (so the next call re-opens once the
+                    # maintainer has caught up) and skip this frame.
+                    try:
+                        shm.close()
+                    except Exception:
+                        pass
+                    return None
                 self.shm_store[name] = shm
             return np.ndarray(shape, dtype=np.uint8, buffer=shm.buf)
         except FileNotFoundError: