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S." Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=jsnow@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: multipart/alternative; boundary="0000000000008e9cd705c9da8db8" Received-SPF: pass client-ip=216.205.24.124; envelope-from=jsnow@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.7, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Eduardo Habkost , Kashyap Chamarthy , Markus Armbruster , Wainer Moschetta , qemu-devel , Stefan Hajnoczi , Cleber Rosa , Eric Blake Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" --0000000000008e9cd705c9da8db8 Content-Type: text/plain; charset="UTF-8" On Tue, Aug 17, 2021 at 3:07 PM Niteesh G. S. wrote: > > > On Tue, Aug 17, 2021 at 10:21 AM John Snow wrote: > >> >> >> On Fri, Jul 30, 2021 at 4:19 PM G S Niteesh Babu >> wrote: >> >> [...] > >> >>> + >>> + >>> class App(QMPClient): >>> - def __init__(self, address: Union[str, Tuple[str, int]]) -> None: >>> + def __init__(self, address: Union[str, Tuple[str, int]], >>> num_retries: int, >>> + retry_delay: Optional[int]) -> None: >>> urwid.register_signal(type(self), UPDATE_MSG) >>> self.window = Window(self) >>> self.address = address >>> self.aloop: Optional[Any] = None # FIXME: Use more concrete >>> type. >>> + self.num_retries = num_retries >>> + self.retry_delay = retry_delay >>> + self.retry: bool = False >>> + self.disconnecting: bool = False >>> >> >> Why is this one needed again ? ... >> > > A race condition occurs in protocol.py line 597 > The reason behind this is there are two disconnect calls initiated. The > first one via kill_app > and the second one via manage_connection when the state is set to > disconnecting by the first call. > One of the calls set's the state to IDLE(protocol.py:584) after it has > finished disconnecting, meanwhile > the second call is somehow in the process of disconnecting and assert the > state to be in DISCONNECTING > in protocol.py:597, which it is not since it has been set to IDLE by the > first call. > > If I don't gaurd against the second call I get the following exception > > ------------------------------------------------------------------------------------------ > Traceback (most recent call last): > File "/home/niteesh/development/qemu/python/.venv/bin/aqmp-tui", line > 33, in > sys.exit(load_entry_point('qemu', 'console_scripts', 'aqmp-tui')()) > File "/home/niteesh/development/qemu/python/qemu/aqmp/aqmp_tui.py", line > 695, in main > app.run(args.asyncio_debug) > File "/home/niteesh/development/qemu/python/qemu/aqmp/aqmp_tui.py", line > 444, in run > raise err > File "/home/niteesh/development/qemu/python/qemu/aqmp/aqmp_tui.py", line > 441, in run > main_loop.run() > File > "/home/niteesh/development/qemu/python/.venv/lib/python3.6/site-packages/urwid/main_loop.py", > line 287, in run > self._run() > File > "/home/niteesh/development/qemu/python/.venv/lib/python3.6/site-packages/urwid/main_loop.py", > line 385, in _run > self.event_loop.run() > File > "/home/niteesh/development/qemu/python/.venv/lib/python3.6/site-packages/urwid/main_loop.py", > line 1494, in run > reraise(*exc_info) > File > "/home/niteesh/development/qemu/python/.venv/lib/python3.6/site-packages/urwid/compat.py", > line 58, in reraise > raise value > File "/home/niteesh/development/qemu/python/qemu/aqmp/aqmp_tui.py", line > 391, in manage_connection > await self.disconnect() > File "/home/niteesh/development/qemu/python/qemu/aqmp/aqmp_tui.py", line > 312, in disconnect > raise err > File "/home/niteesh/development/qemu/python/qemu/aqmp/aqmp_tui.py", line > 300, in disconnect > await super().disconnect() > File "/home/niteesh/development/qemu/python/qemu/aqmp/protocol.py", line > 302, in disconnect > await self._wait_disconnect() > File "/home/niteesh/development/qemu/python/qemu/aqmp/protocol.py", line > 583, in _wait_disconnect > self._cleanup() > File "/home/niteesh/development/qemu/python/qemu/aqmp/qmp_client.py", > line 331, in _cleanup > super()._cleanup() > File "/home/niteesh/development/qemu/python/qemu/aqmp/protocol.py", line > 597, in _cleanup > assert self.runstate == Runstate.DISCONNECTING > AssertionError > > ------------------------------------------------------------------------------------------- > Hm, OK. I'm not sure if this is a bug on my part or not yet, I'll investigate. > def add_to_history(self, msg: str, level: Optional[str] = None) -> >>> None: >>> @@ -119,7 +132,7 @@ def _cb_inbound(self, msg: Message) -> Message: >>> LOGGER.info('Error server disconnected before reply') >>> urwid.emit_signal(self, UPDATE_MSG, >>> '{"error": "Server disconnected before >>> reply"}') >>> - self._set_status("Server disconnected") >>> + await self.disconnect() >>> except Exception as err: >>> LOGGER.error('Exception from _send_to_server: %s', str(err)) >>> raise err >>> @@ -136,15 +149,29 @@ def kill_app(self) -> None: >>> create_task(self._kill_app()) >> >> Is this required? I would have hoped that after calling disconnect that >> the state would have again changed to IDLE and you wouldn't need this >> clause here. >> > After you mentioned it I too felt it was redundant. But on removing it the > whole app freezes when trying to exit. > I logged the state after the call to disconnect, instead of being in the > IDLE state, it is still in DISCONNECTING state. > I suspect this results in the constant infinite looping which doesn't give > other coroutines a chance to run and blocks > the event loop thus resulting in the freezing of the app. But I am not > sure why the state isn't changing to IDLE. > Hmm ... That may well be a bug in AQMP then. I will investigate. --0000000000008e9cd705c9da8db8 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable


=
On Tue, Aug 17, 2021 at 3:07 PM Nitee= sh G. S. <niteesh.gs@gmail.com> wrote:


On= Tue, Aug 17, 2021 at 10:21 AM John Snow <jsnow@redhat.com> wrote:
<= br>

On Fri, Jul 30, 2021 at 4:19 PM G S Niteesh Babu <niteesh.gs@gmail.com> wrote:<= br>


[...]
=C2=A0
=C2=A0
+
+
=C2=A0class App(QMPClient):
-=C2=A0 =C2=A0 def __init__(self, address: Union[str, Tuple[str, int]]) -&g= t; None:
+=C2=A0 =C2=A0 def __init__(self, address: Union[str, Tuple[str, int]], num= _retries: int,
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0retry_delay:= Optional[int]) -> None:
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0urwid.register_signal(type(self), UPDATE_= MSG)
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0self.window =3D Window(self)
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0self.address =3D address
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0self.aloop: Optional[Any] =3D None=C2=A0 = # FIXME: Use more concrete type.
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 self.num_retries =3D num_retries
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 self.retry_delay =3D retry_delay
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 self.retry: bool =3D False
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 self.disconnecting: bool =3D False

Why is this one needed again ? ...
=
=C2=A0
A race condition = occurs in protocol.py line 597
The reas= on behind this is there are two disconnect calls initiated. The first one v= ia kill_app
and the second one via mana= ge_connection when the state is set to disconnecting by the first call.
One of the calls set's the state to ID= LE(protocol.py:584) after it has finished disconnecting, meanwhile
the second call is somehow in the process of di= sconnecting and assert the state to be in DISCONNECTING
in protocol.py:597, which it is not since it has been set = to IDLE by the first call.

If I don't gaurd against the second = call I get the following exception
----= ---------------------------------------------------------------------------= -----------
Traceback (most recent call= last):
=C2=A0 File "/home/niteesh/development/qemu/python/.venv/bi= n/aqmp-tui", line 33, in <module>
=C2=A0 =C2=A0 sys.exit(load= _entry_point('qemu', 'console_scripts', 'aqmp-tui')= ())
=C2=A0 File "/home/niteesh/development/qemu/python/qemu/aqmp/aq= mp_tui.py", line 695, in main
=C2=A0 =C2=A0 app.run(args.asyncio_de= bug)
=C2=A0 File "/home/niteesh/development/qemu/python/qemu/aqmp/a= qmp_tui.py", line 444, in run
=C2=A0 =C2=A0 raise err
=C2=A0 Fil= e "/home/niteesh/development/qemu/python/qemu/aqmp/aqmp_tui.py", = line 441, in run
=C2=A0 =C2=A0 main_loop.run()
=C2=A0 File "/hom= e/niteesh/development/qemu/python/.venv/lib/python3.6/site-packages/urwid/m= ain_loop.py", line 287, in run
=C2=A0 =C2=A0 self._run()
=C2=A0 = File "/home/niteesh/development/qemu/python/.venv/lib/python3.6/site-p= ackages/urwid/main_loop.py", line 385, in _run
=C2=A0 =C2=A0 self.e= vent_loop.run()
=C2=A0 File "/home/niteesh/development/qemu/python/= .venv/lib/python3.6/site-packages/urwid/main_loop.py", line 1494, in r= un
=C2=A0 =C2=A0 reraise(*exc_info)
=C2=A0 File "/home/niteesh/d= evelopment/qemu/python/.venv/lib/python3.6/site-packages/urwid/compat.py&qu= ot;, line 58, in reraise
=C2=A0 =C2=A0 raise value
=C2=A0 File "= /home/niteesh/development/qemu/python/qemu/aqmp/aqmp_tui.py", line 391= , in manage_connection
=C2=A0 =C2=A0 await self.disconnect()
=C2=A0 F= ile "/home/niteesh/development/qemu/python/qemu/aqmp/aqmp_tui.py"= , line 312, in disconnect
=C2=A0 =C2=A0 raise err
=C2=A0 File "/= home/niteesh/development/qemu/python/qemu/aqmp/aqmp_tui.py", line 300,= in disconnect
=C2=A0 =C2=A0 await super().disconnect()
=C2=A0 File &= quot;/home/niteesh/development/qemu/python/qemu/aqmp/protocol.py", lin= e 302, in disconnect
=C2=A0 =C2=A0 await self._wait_disconnect()
=C2= =A0 File "/home/niteesh/development/qemu/python/qemu/aqmp/protocol.py&= quot;, line 583, in _wait_disconnect
=C2=A0 =C2=A0 self._cleanup()
= =C2=A0 File "/home/niteesh/development/qemu/python/qemu/aqmp/qmp_clien= t.py", line 331, in _cleanup
=C2=A0 =C2=A0 super()._cleanup()
= =C2=A0 File "/home/niteesh/development/qemu/python/qemu/aqmp/protocol.= py", line 597, in _cleanup
=C2=A0 =C2=A0 assert self.runstate =3D= =3D Runstate.DISCONNECTING
AssertionError
-----------------------------------------------------------------= --------------------------

Hm, OK. I'm not sure if this is a bug on my part or not yet, I'll= investigate.
=C2=A0
=C2=A0 =C2=A0 =C2=A0def add_to_history(self, msg: str, level: Optional[str]= =3D None) -> None:
@@ -119,7 +132,7 @@ def _cb_inbound(self, msg: Message) -> Message:
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0LOGGER.info('Error serv= er disconnected before reply')
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0urwid.emit_signal(self, UPD= ATE_MSG,
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2= =A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0'{"error": "Server= disconnected before reply"}')
-=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 self._set_status("Server di= sconnected")
+=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 await self.disconnect()
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0except Exception as err:
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0LOGGER.error('Exception= from _send_to_server: %s', str(err))
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0raise err
@@ -136,15 +149,29 @@ def kill_app(self) -> None:
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0create_task(self._kill_app())
Is this required? I would= have hoped that after calling disconnect that the state would have again c= hanged to IDLE and you wouldn't need this clause here.
<= /div>
After you mentioned i= t I too felt it was redundant. But on removing it the whole app freezes whe= n trying to exit.
I logged the st= ate after the call to disconnect, instead of being in the IDLE state, it is= still in DISCONNECTING state.
I suspec= t this results in the constant infinite looping which doesn't give othe= r coroutines a chance to run and blocks
the event loop thus resulting in the freezing of the app. But I am not sur= e why the state isn't changing to IDLE.
<= div>
Hmm ... That may well be a bug in AQMP then. I will inve= stigate.
--0000000000008e9cd705c9da8db8--