From a69af67db34b25f7cc1546902f7ce6acc77977bf Mon Sep 17 00:00:00 2001
From: ipeluffo <ipeluffo@gmail.com>
Date: Tue, 14 Apr 2026 11:18:15 +0100
Subject: [PATCH] Refactor `Dependant.is_coroutine_callable` property for
 improved memory usage

```
Samples: 200000 - current=318.4 MB  peak=318.4 MB
Samples: 100000 - current=159.2 MB  peak=159.2 MB
Samples: 50000 - current=79.6 MB  peak=79.6 MB
Samples: 1000 - current=1.6 MB  peak=1.6 MB
Samples: 500 - current=0.8 MB  peak=0.8 MB
```
---
 fastapi/dependencies/models.py | 69 ++++++++++++++++++++--------------
 1 file changed, 41 insertions(+), 28 deletions(-)

diff --git a/fastapi/dependencies/models.py b/fastapi/dependencies/models.py
index a19afd2fa8..f1aace7329 100644
--- a/fastapi/dependencies/models.py
+++ b/fastapi/dependencies/models.py
@@ -58,6 +58,7 @@ class Dependant:
     _security_dependencies_cache: list["Dependant"] = field(default=None, init=False, repr=False)
     _is_gen_callable_cache: bool = field(default=None, init=False, repr=False)
     _is_async_gen_callable_cache: bool = field(default=None, init=False, repr=False)
+    _is_coroutine_callable_cache: bool = field(default=None, init=False, repr=False)
 
     @property
     def oauth_scopes(self) -> list[str]:
@@ -210,35 +211,47 @@ class Dependant:
 
         return self._is_async_gen_callable_cache
 
-    @cached_property
+    @property
     def is_coroutine_callable(self) -> bool:
-        if self.call is None:
-            return False  # pragma: no cover
-        if inspect.isroutine(_impartial(self.call)) and iscoroutinefunction(
-            _impartial(self.call)
-        ):
-            return True
-        if inspect.isroutine(_unwrapped_call(self.call)) and iscoroutinefunction(
-            _unwrapped_call(self.call)
-        ):
-            return True
-        if inspect.isclass(_unwrapped_call(self.call)):
-            return False
-        dunder_call = getattr(_impartial(self.call), "__call__", None)  # noqa: B004
-        if dunder_call is None:
-            return False  # pragma: no cover
-        if iscoroutinefunction(_impartial(dunder_call)) or iscoroutinefunction(
-            _unwrapped_call(dunder_call)
-        ):
-            return True
-        dunder_unwrapped_call = getattr(_unwrapped_call(self.call), "__call__", None)  # noqa: B004
-        if dunder_unwrapped_call is None:
-            return False  # pragma: no cover
-        if iscoroutinefunction(
-            _impartial(dunder_unwrapped_call)
-        ) or iscoroutinefunction(_unwrapped_call(dunder_unwrapped_call)):
-            return True
-        return False
+        if self._is_coroutine_callable_cache is None:
+            if self.call is None:
+                self._is_coroutine_callable_cache = False  # pragma: no cover
+            elif inspect.isroutine(_impartial(self.call)) and iscoroutinefunction(
+                _impartial(self.call)
+            ):
+                self._is_coroutine_callable_cache = True
+            elif inspect.isroutine(_unwrapped_call(self.call)) and iscoroutinefunction(
+                _unwrapped_call(self.call)
+            ):
+                self._is_coroutine_callable_cache = True
+            elif inspect.isclass(_unwrapped_call(self.call)):
+                self._is_coroutine_callable_cache = False
+
+            if self._is_coroutine_callable_cache is not None:
+                return self._is_coroutine_callable_cache
+
+            dunder_call = getattr(_impartial(self.call), "__call__", None)  # noqa: B004
+            if dunder_call is None:
+                self._is_coroutine_callable_cache = False  # pragma: no cover
+            elif iscoroutinefunction(_impartial(dunder_call)) or iscoroutinefunction(
+                _unwrapped_call(dunder_call)
+            ):
+                self._is_coroutine_callable_cache = True
+
+            if self._is_coroutine_callable_cache is not None:
+                return self._is_coroutine_callable_cache
+
+            dunder_unwrapped_call = getattr(_unwrapped_call(self.call), "__call__", None)  # noqa: B004
+            if dunder_unwrapped_call is None:
+                self._is_coroutine_callable_cache = False  # pragma: no cover
+            elif iscoroutinefunction(
+                _impartial(dunder_unwrapped_call)
+            ) or iscoroutinefunction(_unwrapped_call(dunder_unwrapped_call)):
+                self._is_coroutine_callable_cache = True
+            else:
+                self._is_coroutine_callable_cache = False
+        
+        return self._is_coroutine_callable_cache
 
     @cached_property
     def computed_scope(self) -> str | None: