From 569af7506940c925ca5697d0f15f732d92e17896 Mon Sep 17 00:00:00 2001
From: richardsheridan <richard.sheridan@gmail.com>
Date: Sun, 30 Jul 2023 09:55:55 -0400
Subject: [PATCH] add extra assertion for deadlock prevention

---
 trio_parallel/_impl.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/trio_parallel/_impl.py b/trio_parallel/_impl.py
index 59847bf4..d25a6293 100644
--- a/trio_parallel/_impl.py
+++ b/trio_parallel/_impl.py
@@ -185,6 +185,7 @@ async def _aclose(self):
         self._lifetime.waiting_task = trio.lowlevel.current_task()
         with trio.CancelScope(shield=True):
             if self._lifetime.calc_running() != 0:
+                assert self is not get_default_context()
                 await trio.sleep_forever()  # woken by self._lifetime.__aexit__
             await trio.to_thread.run_sync(
                 self._worker_cache.shutdown, self.grace_period