dify

dify/api/gunicorn.conf.py

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+import psycogreen.gevent as pscycogreen_gevent  # type: ignore
+from gevent import events as gevent_events
+from grpc.experimental import gevent as grpc_gevent  # type: ignore
+
+# WARNING: This module is loaded very early in the Gunicorn worker lifecycle,
+# before gevent's monkey-patching is applied. Importing modules at the top level here can
+# interfere with gevent's ability to properly patch the standard library,
+# potentially causing subtle and difficult-to-diagnose bugs.
+#
+# To ensure correct behavior, defer any initialization or imports that depend on monkey-patching
+# to the `post_patch` hook below, or use a gevent_events subscriber as shown.
+#
+# For further context, see: https://github.com/langgenius/dify/issues/26689
+#
+# Note: The `post_fork` hook is also executed before monkey-patching,
+# so moving imports there does not resolve this issue.
+
+# NOTE(QuantumGhost): here we cannot use post_fork to patch gRPC, as
+# grpc_gevent.init_gevent must be called after patching stdlib.
+# Gunicorn calls `post_init` before applying monkey patch.
+# Use `post_init` to setup gRPC gevent support would cause deadlock and
+# some other weird issues.
+#
+# ref:
+# - https://github.com/grpc/grpc/blob/62533ea13879d6ee95c6fda11ec0826ca822c9dd/src/python/grpcio/grpc/experimental/gevent.py
+# - https://github.com/gevent/gevent/issues/2060#issuecomment-3016768668
+# - https://github.com/benoitc/gunicorn/blob/23.0.0/gunicorn/arbiter.py#L605-L609
+
+
+def post_patch(event):
+    # this function is only called for gevent worker.
+    # from gevent docs (https://www.gevent.org/api/gevent.monkey.html):
+    # You can also subscribe to the events to provide additional patching beyond what gevent distributes, either for
+    # additional standard library modules, or for third-party packages. The suggested time to do this patching is in
+    # the subscriber for gevent.events.GeventDidPatchBuiltinModulesEvent.
+    if not isinstance(event, gevent_events.GeventDidPatchBuiltinModulesEvent):
+        return
+    # grpc gevent
+    grpc_gevent.init_gevent()
+    print("gRPC patched with gevent.", flush=True)  # noqa: T201
+    pscycogreen_gevent.patch_psycopg()
+    print("psycopg2 patched with gevent.", flush=True)  # noqa: T201
+
+
+gevent_events.subscribers.append(post_patch)