Hi, That last thing is pretty interesting. It’s either the issue fixed by this patch [1] or sessions are somehow cleaned up multiple times. If it’s the latter, I’d really like to understand how that happens.
Regards, Florin [1] https://gerrit.fd.io/r/c/vpp/+/38507 > On Mar 20, 2023, at 6:52 PM, Zhang Dongya <fortitude.zh...@gmail.com> wrote: > > Hi, > > After merge this patch and update the test environment, the issue still > persists. > > Let me clear my client app config: > 1. register a reset callback, which will call vnet_disconnect there and also > trigger reconnect by send event to the ctrl process.) > 2. register a connected callback, which will handle connect err by trigger > reconnect, on success, it will record session handle and extract tcp sequence > for our app usage. > 3. register a disconnect callback, which basically do same as reset callback. > 4. register a cleanup callback and accept callback, which basically make the > session layer happy without actually relevant work to do. > > There is a ctrl process in mater, which will handle periodically reconnect or > triggered by event. > > BTW, I also see frequently warning 'session %u hash delete rv -3' in > session_delete in my environment, hope this helps to investigate. > > Florin Coras <fcoras.li...@gmail.com <mailto:fcoras.li...@gmail.com>> > 于2023年3月20日周一 23:29写道： >> Hi, >> >> Understood and yes, connect will synchronously fail if port is not >> available, so you should be able to retry it later. >> >> Regards, >> Florin >> >>> On Mar 20, 2023, at 1:58 AM, Zhang Dongya <fortitude.zh...@gmail.com >>> <mailto:fortitude.zh...@gmail.com>> wrote: >>> >>> Hi, >>> >>> It seems the issue occurs when there are disconnect called because our >>> network can't guarantee a tcp can't be reset even when 3 ways handshake is >>> completed (firewall issue :( ). >>> >>> When we find the app layer timeout, we will first disconnect (because we >>> record the session handle, this session might be a half open session), does >>> vnet session layer guarantee that if we reconnect from master thread when >>> the half open session still not be released yet (due to asynchronous logic) >>> that the reconnect fail? if then we can retry connect later. >>> >>> I prefer to not registered half open callback because I think it make app >>> complicated from a TCP programming prospective. >>> >>> For your patch, I think it should be work because I can't delete the half >>> open session immediately because there is worker configured, so the half >>> open will be removed from bihash when syn retrans timeout. I have merged >>> the patch and will provide feedback later. >>> >>> Florin Coras <fcoras.li...@gmail.com <mailto:fcoras.li...@gmail.com>> >>> 于2023年3月20日周一 13:09写道： >>>> Hi, >>>> >>>> Inline. >>>> >>>>> On Mar 19, 2023, at 6:47 PM, Zhang Dongya <fortitude.zh...@gmail.com >>>>> <mailto:fortitude.zh...@gmail.com>> wrote: >>>>> >>>>> Hi, >>>>> >>>>> It can be aborted both in established state or half open state because I >>>>> will do timeout in our app layer. >>>> >>>> [fc] Okay! Is the issue present irrespective of the state of the session >>>> or does it happen only after a disconnect in hanf-open state? More lower. >>>> >>>>> >>>>> Regarding your question, >>>>> >>>>> - Yes we add a builtin in app relys on C apis that mainly use >>>>> vnet_connect/disconnect to connect or disconnect session. >>>> >>>> [fc] Understood >>>> >>>>> - We call these api in a vpp ctrl process which should be running on the >>>>> master thread, we never do session setup/teardown on worker thread. (the >>>>> environment that found this issue is configured with 1 master + 1 worker >>>>> setup.) >>>> >>>> [fc] With vpp latest it’s possible to connect from first workers. It’s an >>>> optimization meant to avoid 1) worker barrier on syns and 2) entering poll >>>> mode on main (consume less cpu) >>>> >>>>> - We started to develop the app using 22.06 and I keep to merge upstream >>>>> changes to latest vpp by cherry-picking. The reason for line mismatch is >>>>> that I added some comment to the session layer code, it should be equal >>>>> to the master branch now. >>>> >>>> [fc] Ack >>>> >>>>> >>>>> When reading the code I understand that we mainly want to cleanup half >>>>> open from bihash in session_stream_connect_notify, however, in syn-sent >>>>> state if I choose to close the session, the session might be closed by my >>>>> app due to session setup timeout (in second scale), in that case, session >>>>> will be marked as half_open_done and half open session will be freed >>>>> shortly in the ctrl thread (the 1st worker?). >>>> >>>> [fc] Actually, this might be the issue. We did start to provide a >>>> half-open session handle to apps which if closed does clean up the session >>>> but apparently it is missing the cleanup of the session lookup table. >>>> Could you try this patch [1]? It might need additional work. >>>> >>>> Having said that, forcing a close/cleanup will not free the port >>>> synchronously. So, if you’re using fixed ports, you’ll have to wait for >>>> the half-open cleanup notification. >>>> >>>>> >>>>> Should I also registered half open callback or there are some other >>>>> reason that lead to this failure? >>>>> >>>> >>>> [fc] Yes, see above. >>>> >>>> Regards, >>>> Florin >>>> >>>> [1] https://gerrit.fd.io/r/c/vpp/+/38526 >>>> >>>>> >>>>> Florin Coras <fcoras.li...@gmail.com <mailto:fcoras.li...@gmail.com>> >>>>> 于2023年3月20日周一 06:22写道： >>>>>> Hi, >>>>>> >>>>>> When you abort the connection, is it fully established or half-open? >>>>>> Half-opens are cleaned up by the owner thread after a timeout, but the >>>>>> 5-tuple should be assigned to the fully established session by that >>>>>> point. tcp_half_open_connection_cleanup does not cleanup the bihash >>>>>> instead session_stream_connect_notify does once tcp connect returns >>>>>> either success or failure. >>>>>> >>>>>> So a few questions: >>>>>> - is it accurate to assume you have a builtin vpp app and rely only on C >>>>>> apis to interact with host stack? >>>>>> - on what thread (main or first worker) do you call vnet_connect? >>>>>> - what api do you use to close the session? >>>>>> - what version of vpp is this because lines don’t match vpp latest? >>>>>> >>>>>> Regards, >>>>>> Florin >>>>>> >>>>>> > On Mar 19, 2023, at 2:08 AM, Zhang Dongya <fortitude.zh...@gmail.com >>>>>> > <mailto:fortitude.zh...@gmail.com>> wrote: >>>>>> > >>>>>> > Hi list, >>>>>> > >>>>>> > recently in our application, we constantly triggered such abrt issue >>>>>> > which make our connectivity interrupt for a while: >>>>>> > >>>>>> > Mar 19 16:11:26 ubuntu vnet[2565933]: received signal SIGABRT, PC >>>>>> > 0x7fefd3b2000b >>>>>> > Mar 19 16:11:26 ubuntu vnet[2565933]: >>>>>> > /home/fortitude/glx/vpp/src/vnet/tcp/tcp_input.c:3004 >>>>>> > (tcp46_input_inline) assertion `tcp_lookup_is_valid (tc0, b[0], >>>>>> > tcp_buffer_hdr (b[0]))' fails >>>>>> > >>>>>> > Our scenario is quite simple, we will make 4 parallel tcp connection >>>>>> > (use 4 fixed source ports) to a remote vpp stack (fixed ip and port), >>>>>> > and will do some keepalive in our application layer, since we only use >>>>>> > the vpp tcp stack to make the middle box happy with the connection, we >>>>>> > do not use the data transport of tcp statck actually. >>>>>> > >>>>>> > However, since the network condition is complex, we have to always >>>>>> > need to abrt the connection and reconnect. >>>>>> > >>>>>> > I keep to merge upstream session and tcp fix however the issue still >>>>>> > not fixed, what I found now it may be in some case >>>>>> > tcp_half_open_connection_cleanup may not deleted the half open session >>>>>> > from the lookup table (bihash) and the session index is realloced by >>>>>> > other connection. >>>>>> > >>>>>> > Hope the list can provide some hint about how to overcome this issue, >>>>>> > thanks a lot. >>>>>> > >>>>>> > >>>>>> > >>>>>> >>>>>> >>>>>> >>>>>> >>>>> >>>> >>>> >>>> >>>> >>> >> >> >> >> > >
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