fix: close idle conn without awaiting in acquire to prevent cancellat…

async_postgres/pg_pool.nim

@@ -821,17 +821,13 @@ proc acquireImpl(pool: PgPool): Future[AcquireResult] {.async.} =
     while pool.idle.len > 0:
       let pc = pool.idle.popFirst()
       if pc.conn.state != csReady or pc.conn.socketHasFin():
-        pool.metrics.closeCount.inc
-        await pool.tracedClose(pc.conn)
-        if pool.closed:
-          raisePoolClosed()
+        # closeNoWait: avoid an await point where a cancellation could be
+        # swallowed by tracedClose and leak the next acquired conn (see ping guard).
+        pool.closeNoWait(pc.conn)
         continue
       if pool.config.maxLifetime > ZeroDuration and
           now - pc.conn.createdAt > pool.config.maxLifetime:
-        pool.metrics.closeCount.inc
-        await pool.tracedClose(pc.conn)
-        if pool.closed:
-          raisePoolClosed()
+        pool.closeNoWait(pc.conn)
         continue
       # Health check: ping connections that have been idle too long.
       # TLS connections use the tighter `tlsHealthCheckTimeout` window because
@@ -880,10 +876,7 @@ proc acquireImpl(pool: PgPool): Future[AcquireResult] {.async.} =
           raise e
         except CatchableError:
           pool.active.dec
-          pool.metrics.closeCount.inc
-          await pool.tracedClose(pc.conn)
-          if pool.closed:
-            raisePoolClosed()
+          pool.closeNoWait(pc.conn)
           continue
         # A close() during the ping didn't drain the popped conn — discard it.
         if pool.closed:

tests/test_pool.nim

@@ -597,6 +597,34 @@ suite "Pool acquire":
     check pool.active == 1
     check pool.idle.len == 0
 
+  test "acquire disposes idle broken conn via closeNoWait (no await point)":
+    # Regression: `await tracedClose` here would let a caller's cancellation
+    # be swallowed by tracedClose's `except CatchableError`, leaking the
+    # next-acquired conn to a departed caller.
+    let pool = makePool()
+    let broken = mockConn(csClosed)
+    let good = mockConn(csReady)
+    pool.idle.addLast(broken.toPooled())
+    pool.idle.addLast(good.toPooled())
+
+    let acquired = waitFor pool.acquire()
+    check acquired == good
+    check pool.pendingBackgroundTasks.len >= 1
+
+  test "acquire disposes maxLifetime-expired idle conn via closeNoWait":
+    let pool = makePool()
+    pool.config.maxLifetime = seconds(1)
+    let expired = mockConn()
+    expired.createdAt = Moment.now() - seconds(5)
+    expired.state = csClosed
+    let good = mockConn()
+    pool.idle.addLast(expired.toPooled())
+    pool.idle.addLast(good.toPooled())
+
+    let acquired = waitFor pool.acquire()
+    check acquired == good
+    check pool.pendingBackgroundTasks.len >= 1
+
   test "acquire registers waiter when at max":
     let pool = makePool(maxSize = 1)
     pool.active = 1