fix memory issues by moving router instantiation out of view __init__ (#77)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: joshuadavidthomas

CHANGELOG.md

@@ -18,6 +18,10 @@ and this project attempts to adhere to [Semantic Versioning](https://semver.org/
 
 ## [Unreleased]
 
+### Fixed
+
+- Fixed excessive memory usage in `AsyncWebhookView` and `SyncWebhookView` caused by creating a new `GitHubRouter` instance on each request.
+
 ## [0.6.0]
 
 ### Added

pyproject.toml

@@ -16,9 +16,10 @@ dev = [
   "pytest-cov>=6.0.0",
   "pytest-django>=4.9.0",
   "pytest-httpx>=0.33.0",
+  "pytest-memray>=1.7.0",
   "pytest-randomly>=3.16.0",
   "pytest-xdist>=3.6.1",
-  "ruff>=0.7.3"
+  "ruff>=0.7.3",
 ]
 types = [
   "django-stubs>=5.1.1",

src/django_github_app/views.py

@@ -27,6 +27,8 @@
 
 GitHubAPIType = TypeVar("GitHubAPIType", AsyncGitHubAPI, SyncGitHubAPI)
 
+_router = GitHubRouter(*GitHubRouter.routers)
+
 
 class BaseWebhookView(View, ABC, Generic[GitHubAPIType]):
     github_api_class: type[GitHubAPIType]
@@ -59,7 +61,7 @@ def get_response(self, event_log: EventLog) -> JsonResponse:
 
     @property
     def router(self) -> GitHubRouter:
-        return GitHubRouter(*GitHubRouter.routers)
+        return _router
 
     @abstractmethod
     def post(

tests/test_routing.py

@@ -0,0 +1,102 @@
+from __future__ import annotations
+
+import pytest
+from django.http import HttpRequest
+from django.http import JsonResponse
+
+from django_github_app.github import SyncGitHubAPI
+from django_github_app.routing import GitHubRouter
+from django_github_app.views import BaseWebhookView
+
+
+@pytest.fixture(autouse=True)
+def test_router():
+    import django_github_app.views
+    from django_github_app.routing import GitHubRouter
+
+    old_routers = GitHubRouter._routers.copy()
+    GitHubRouter._routers = []
+
+    old_router = django_github_app.views._router
+
+    test_router = GitHubRouter()
+    django_github_app.views._router = test_router
+
+    yield test_router
+
+    GitHubRouter._routers = old_routers
+    django_github_app.views._router = old_router
+
+
+class View(BaseWebhookView[SyncGitHubAPI]):
+    github_api_class = SyncGitHubAPI
+
+    def post(self, request: HttpRequest) -> JsonResponse:
+        return JsonResponse({})
+
+
+class LegacyView(BaseWebhookView[SyncGitHubAPI]):
+    github_api_class = SyncGitHubAPI
+
+    @property
+    def router(self) -> GitHubRouter:
+        # Always create a new router (simulating issue #73)
+        return GitHubRouter(*GitHubRouter.routers)
+
+    def post(self, request: HttpRequest) -> JsonResponse:
+        return JsonResponse({})
+
+
+class TestGitHubRouter:
+    def test_router_single_instance(self):
+        view1 = View()
+        view2 = View()
+
+        router1 = view1.router
+        router2 = view2.router
+
+        assert router1 is router2
+        assert view1.router is router1
+        assert view2.router is router2
+
+    def test_no_duplicate_routers(self):
+        router_ids = set()
+
+        for _ in range(1000):
+            view = View()
+            router_ids.add(id(view.router))
+
+        assert len(router_ids) == 1
+
+    def test_duplicate_routers_without_module_level_router(self):
+        router_ids = set()
+
+        for _ in range(5):
+            view = LegacyView()
+            router_ids.add(id(view.router))
+
+        assert len(router_ids) == 5
+
+    @pytest.mark.limit_memory("2.5MB")
+    def test_router_memory_stress_test(self):
+        view_count = 50000
+        views = []
+
+        for _ in range(view_count):
+            view = View()
+            views.append(view)
+
+        assert len(views) == view_count
+        assert all(view.router is views[0].router for view in views)
+
+    @pytest.mark.limit_memory("4MB")
+    def test_router_memory_stress_test_legacy(self):
+        view_count = 50000
+        views = []
+
+        for _ in range(view_count):
+            view = LegacyView()
+            views.append(view)
+
+        assert len(views) == view_count
+        assert not all(view.router is views[0].router for view in views)

tests/test_views.py

@@ -17,7 +17,6 @@
 from django_github_app.github import AsyncGitHubAPI
 from django_github_app.github import SyncGitHubAPI
 from django_github_app.models import EventLog
-from django_github_app.routing import GitHubRouter
 from django_github_app.views import AsyncWebhookView
 from django_github_app.views import BaseWebhookView
 from django_github_app.views import SyncWebhookView
@@ -71,9 +70,21 @@ def _make_request(
 
 @pytest.fixture
 def test_router():
+    import django_github_app.views
+    from django_github_app.routing import GitHubRouter
+
+    old_routers = GitHubRouter._routers.copy()
     GitHubRouter._routers = []
-    yield GitHubRouter()
-    GitHubRouter._routers = []
+
+    old_router = django_github_app.views._router
+
+    test_router = GitHubRouter()
+    django_github_app.views._router = test_router
+
+    yield test_router
+
+    GitHubRouter._routers = old_routers
+    django_github_app.views._router = old_router
 
 
 @pytest.fixture