fix: shutdown should wait for in flight requests

Author: mkleczek

CHANGELOG.md

@@ -19,6 +19,10 @@ All notable changes to this project will be documented in this file. From versio
 - Log error when `db-schemas` config contains schema `pg_catalog` or `information_schema` by @taimoorzaeem in #4359
   + Now fails at startup. Prior to this, it failed with `PGRST205` on requests related to these schemas.
 
+### Fixed
+
+- Shutdown should wait for in flight requests by @mkleczek in #4702
+
 ## [14.6] - 2026-03-06
 
 ### Fixed

nix/overlays/haskell-packages.nix

@@ -78,6 +78,53 @@ let
       hasql-pool = lib.dontCheck prev.hasql-pool_1_0_1;
       hasql-transaction = lib.dontCheck prev.hasql-transaction_1_1_0_1;
       postgresql-binary = lib.dontCheck (lib.doJailbreak prev.postgresql-binary_0_13_1_3);
+
+      http2 =
+        prev.callHackageDirect
+          {
+            pkg = "http2";
+            ver = "5.4.0";
+            sha256 = "sha256-PeEWVd61bQ8G7LvfLeXklzXqNJFaAjE2ecRMWJZESPE=";
+          }
+          { };
+
+      http-semantics =
+        prev.callHackageDirect
+          {
+            pkg = "http-semantics";
+            ver = "0.4.0";
+            sha256 = "sha256-rh0z51EKvsu5rQd5n2z3fSRjjEObouNZSBPO9NFYOF0=";
+          }
+          { };
+
+      network-run =
+        prev.callHackageDirect
+          {
+            pkg = "network-run";
+            ver = "0.5.0";
+            sha256 = "sha256-vbXh+CzxDsGApjqHxCYf/ijpZtUCApFbkcF5gyN0THU=";
+          }
+          { };
+
+      time-manager =
+        prev.callHackageDirect
+          {
+            pkg = "time-manager";
+            ver = "0.2.4";
+            sha256 = "sha256-sAt/331YLQ2IU3z90aKYSq1nxoazv87irsuJp7ZG3pw=";
+          }
+          { };
+
+      warp =
+        lib.dontCheck (prev.callCabal2nixWithOptions "warp"
+          (super.fetchFromGitHub {
+            owner = "mkleczek";
+            repo = "wai";
+            rev = "e9c9e784dee1b54461b94089175a969eb647d262";
+            #sha256 = "sha256-AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=";
+            sha256 = "sha256-q8vgvsNeKM/fHp3H6+W/tR4HicioqeaU9Eo3rb13bLo=";
+          }) "--subpath=warp"
+          { });
     };
 in
 {

src/PostgREST/App.hs

@@ -22,6 +22,7 @@ import GHC.IO.Exception (IOErrorType (..))
 import System.IO.Error  (ioeGetErrorType)
 
 import Control.Monad.Except     (liftEither)
+import Control.Monad.Extra      (whenJust)
 import Data.Either.Combinators  (mapLeft, whenLeft)
 import Data.Maybe               (fromJust)
 import Data.String              (IsString (..))
@@ -78,8 +79,10 @@ run appState = do
 
   AppState.schemaCacheLoader appState -- Loads the initial SchemaCache
   (mainSocket, adminSocket) <- initSockets conf
-
-  Unix.installSignalHandlers (AppState.getMainThreadId appState) (AppState.schemaCacheLoader appState) (AppState.readInDbConfig False appState)
+  let closeSockets = do
+        whenJust adminSocket NS.close
+        NS.close mainSocket
+  Unix.installSignalHandlers closeSockets (AppState.schemaCacheLoader appState) (AppState.readInDbConfig False appState)
 
   Listener.runListener appState
 
@@ -91,6 +94,10 @@ run appState = do
     address <- resolveSocketToAddress mainSocket
     observer $ AppServerAddressObs address
 
+  -- Hardcoding maximum graceful shutdown timeout (arbitrary set to 5 seconds)
+  -- This is unfortunate but necessary becase graceful shutdowns don't work with HTTP keep-alive
+  -- causing Warp to handle requests on already opened connections even if the listen socket is closed
+  -- See: https://github.com/yesodweb/wai/issues/853
   Warp.runSettingsSocket (serverSettings conf & setOnException onWarpException) mainSocket app
   where
     observer = AppState.getObserver appState

src/PostgREST/Unix.hs

@@ -18,10 +18,9 @@ import           System.Directory (removeFile)
 import           System.IO.Error  (isDoesNotExistError)
 
 -- | Set signal handlers, only for systems with signals
-installSignalHandlers :: ThreadId -> IO () -> IO () -> IO ()
+installSignalHandlers :: IO () -> IO () -> IO () -> IO ()
 #ifndef mingw32_HOST_OS
-installSignalHandlers tid usr1 usr2 = do
-  let interrupt = throwTo tid UserInterrupt
+installSignalHandlers interrupt usr1 usr2 = do
   install Signals.sigINT interrupt
   install Signals.sigTERM interrupt
   install Signals.sigUSR1 usr1

test/io/test_io.py

@@ -105,7 +105,6 @@ def sleep():
         t.join()
 
 
-@pytest.mark.xfail(reason="Graceful shutdown is currently failing", strict=True)
 def test_graceful_shutdown_waits_for_in_flight_request(defaultenv):
     "SIGTERM should allow in-flight requests to finish before exiting"