workaround: reintroduce gevent.Timeout handling

This is probably wrong. But less wrong than handling *all*
BaseException. Reports of this happening may be the result of
 some *other* async Timeout in the wsgi app bubbling through to us.

Gevent docs promise:
"[..] if *exception* is the literal ``False``, the timeout is still raised,
   but the context manager suppresses it, so
   the code outside the with-block won't see it."

gunicorn/workers/base.py

@@ -29,6 +29,8 @@
 
 class Worker:
 
+    WORKAROUND_BASE_EXCEPTIONS = ()  # none
+
     SIGNALS = [getattr(signal, "SIG%s" % x) for x in (
         "ABRT HUP QUIT INT TERM USR1 USR2 WINCH CHLD".split()
     )]

gunicorn/workers/base_async.py

@@ -81,6 +81,9 @@ def handle(self, listener, client, addr):
                     self.log.debug("Ignoring socket not connected")
                 else:
                     self.log.debug("Ignoring EPIPE")
+        except self.WORKAROUND_BASE_EXCEPTIONS as e:
+            self.log.warning("Catched async exception (compat workaround). If this is not a bug in your app, please file a report.")
+            self.handle_error(req, client, addr, e)
         except Exception as e:
             self.handle_error(req, client, addr, e)
         finally:

gunicorn/workers/geventlet.py

@@ -123,6 +123,8 @@ def patch_sendfile():
 
 class EventletWorker(AsyncWorker):
 
+    WORKAROUND_BASE_EXCEPTIONS = (eventlet.Timeout, )
+
     def patch(self):
         hubs.use_hub()
         eventlet.monkey_patch()

gunicorn/workers/ggevent.py

@@ -31,6 +31,8 @@
 
 class GeventWorker(AsyncWorker):
 
+    WORKAROUND_BASE_EXCEPTIONS = (gevent.Timeout, )
+
     server_class = None
     wsgi_handler = None
 

gunicorn/workers/sync.py

@@ -110,6 +110,8 @@ def run_for_multiple(self, timeout):
                 return
 
     def run(self):
+        assert len(self.WORKAROUND_BASE_EXCEPTIONS) == 0
+
         # if no timeout is given the worker will never wait and will
         # use the CPU for nothing. This minimal timeout prevent it.
         timeout = self.timeout or 0.5