Try better shutdown cleanup behaviour (#657)

gcsfs/core.py

@@ -17,6 +17,7 @@
 from urllib.parse import quote as quote_urllib
 from urllib.parse import urlsplit
 
+import aiohttp
 import fsspec
 from fsspec import asyn
 from fsspec.callbacks import NoOpCallback
@@ -351,27 +352,43 @@ def project(self):
     # in-thread asynchronous cleanup first, then fallback to synchronous
     # cleanup (which can handle cross-thread calls).
     @staticmethod
-    def close_session(loop, session):
-        if loop is not None and session is not None:
+    def close_session(loop, session: aiohttp.ClientSession, asynchronous=False):
+        if session.closed:
+            return
+        force_close = False
+        try:
+            current_loop = asyncio.get_running_loop()
+        except RuntimeError:
+            current_loop = None
+        if loop:
+            # an explicit loop was set
             if loop.is_running():
-                try:
-                    current_loop = asyncio.get_running_loop()
-                    current_loop.create_task(session.close())
-                    return
-                except RuntimeError:
-                    pass
-
-                try:
-                    asyn.sync(loop, session.close, timeout=0.1)
-                except fsspec.FSTimeoutError:
-                    pass
+                loop.create_task(session.close())
             else:
-                pass
+                force_close = True
+        elif current_loop is not None and current_loop.is_running() and asynchronous:
+            # running in a concurrnet context
+            current_loop.create_task(session.close())
+        elif asyn.loop[0] is not None and asyn.loop[0].is_running():
+            try:
+                asyn.sync(asyn.loop[0], session.close, timeout=0.1)
+            except fsspec.FSTimeoutError:
+                force_close = True
+        else:
+            force_close = True
+        if force_close:
+            # during shutdown, this is the fallback
+            connector = getattr(session, "_connector", None)
+            if connector is not None:
+                # close after loop is dead
+                connector._close()
 
     async def _set_session(self):
         if self._session is None:
             self._session = await get_client(**self.session_kwargs)
-            weakref.finalize(self, self.close_session, self.loop, self._session)
+            weakref.finalize(
+                self, self.close_session, self.loop, self._session, self.asynchronous
+            )
         return self._session
 
     @property