fix(llama): release a vision chat handler's mtmd context on close (#2342) (#2343)

* fix(llama): release a vision chat handler's mtmd context on close (#2342)

`Llama.close()` tore down the model and its context but left the chat
handler's `_exit_stack` untouched, so the mtmd/clip context it built from
that model was never freed.

Handlers routinely outlive the `Llama` that initialized them -- callers
construct one handler and reuse it across loads -- and
`_init_mtmd_context()` returns early while `mtmd_ctx` is set. After the
first `close()` the handler therefore kept a context bound to an
already-freed model and handed it back on the next load, where it
surfaces as a null `mtmd_ctx` on the C++ side.

Register the handler's exit stack on the Llama's `_stack`. It unwinds
LIFO, so the mtmd context is released ahead of the model teardown
registered earlier in `__init__`, and `mtmd_free` resets `mtmd_ctx` to
`None` so the next load re-initializes cleanly. Duck-typed on
`_exit_stack`, which both `Llava15ChatHandler` and `MTMDChatHandler`
(and every subclass) expose.

* fix: bind multimodal context cleanup to model

---------

Co-authored-by: Anai Guo <antai12232931@anaiguo.com>
Co-authored-by: abetlen <abetlen@gmail.com>

Author: 3 people

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - fix(example): retain recurrent state for server MTP rollback
 - feat: update llama.cpp to ggml-org/llama.cpp@adb55e514
 - fix(server): show falsey defaults in CLI help by @cupkk in #2355
+- fix: release multimodal contexts when closing Llama by @Anai-Guo in #2343
 
 ## [0.3.34]
 

llama_cpp/llama_chat_format.py

@@ -9,7 +9,6 @@
 import string
 
 from datetime import datetime
-from contextlib import ExitStack
 from typing import (
     Any,
     Dict,
@@ -2779,7 +2778,6 @@ def __init__(self, clip_model_path: str, verbose: bool = True):
         self.clip_model_path = clip_model_path
         self.verbose = verbose
         self._mtmd_cpp = mtmd_cpp
-        self._exit_stack = ExitStack()
         self.mtmd_ctx: Optional[mtmd_cpp.mtmd_context_p] = None
 
         if not os.path.exists(clip_model_path):
@@ -2825,7 +2823,7 @@ def mtmd_free():
                         self._mtmd_cpp.mtmd_free(self.mtmd_ctx)
                         self.mtmd_ctx = None
 
-            self._exit_stack.callback(mtmd_free)
+            llama_model._stack.callback(mtmd_free)
 
     def load_image(self, image_url: str) -> bytes:
         return self._load_image(image_url)
@@ -3278,7 +3276,6 @@ def __init__(
         self.verbose = verbose
         self.use_gpu = use_gpu
         self._mtmd_cpp = mtmd_cpp
-        self._exit_stack = ExitStack()
         self.mtmd_ctx: Optional[mtmd_cpp.mtmd_context_p] = None
 
         if not os.path.exists(clip_model_path):
@@ -3321,7 +3318,7 @@ def mtmd_free():
                         self._mtmd_cpp.mtmd_free(self.mtmd_ctx)
                         self.mtmd_ctx = None
 
-            self._exit_stack.callback(mtmd_free)
+            llama_model._stack.callback(mtmd_free)
 
     def load_image(self, image_url: str) -> bytes:
         return self._load_image(image_url)