It seems like there's some deadlock bug or undocumented expected behaviour
in gRPC source code.
However for the life of me, I can't make a minimal example to reproduce the
problem.
On Monday, March 7, 2022 at 1:06:32 PM UTC+10 Plin Chen wrote:
> Our Situation is that when we try to close App without shutting gRPC
> client down, the app hangs up there.
> Of course, if we shutdown gRPC client manually several seconds before
> quiting the app, things will go as normal.
> ----
> We are using the latest gRPC-CSharp version. I notice that shutdown method
> is an aync method.
> When the "OnApplicationQuit" event is catched and we try to invoke
> shutdown(gRPC) before the app really quit,
> gRPC ThreadPool would seem like blocking with the quitting process.
> ----
> We've tried 2 workarounds, and either works:
> 1, catch OnApplicationQuit, invoke "shutdown" of gRPC, let the application
> wait for 2 seconds then try to close the app.
> 2, Everytime when client finish calling remote procedure of grpc server,
> shutdown the grpc client at once.
> On Friday, March 4, 2022 at 9:18:19 PM UTC+8 Anh Tran wrote:
>
>> I have some time to revisit this problem today. Running with GRPC
>> VERBOSITY set to DEBUG gives me this (anything starts with*
>> [2022-03-04T23* is my own logging):
>>
>> [2022-03-04T23:15:41+10:00] [workflow_client] [info] [process 501457,
>> thread 501457] Logger level is set at info.
>> [2022-03-04T23:15:41+10:00] [workflow_client] [warning] [process 501457,
>> thread 501457] Persistent not specified and will default to false
>> D0304 23:15:41.640009936 501457 ev_posix.cc:172] Using
>> polling engine: epollex
>> D0304 23:15:41.640079032 501457 lb_policy_registry.cc:42] registering
>> LB policy factory for "grpclb"
>> D0304 23:15:41.640106084 501457 lb_policy_registry.cc:42] registering
>> LB policy factory for "priority_experimental"
>> D0304 23:15:41.640124027 501457 lb_policy_registry.cc:42] registering
>> LB policy factory for "weighted_target_experimental"
>> D0304 23:15:41.640127329 501457 lb_policy_registry.cc:42] registering
>> LB policy factory for "pick_first"
>> D0304 23:15:41.640150128 501457 lb_policy_registry.cc:42] registering
>> LB policy factory for "round_robin"
>> D0304 23:15:41.640153574 501457 lb_policy_registry.cc:42] registering
>> LB policy factory for "ring_hash_experimental"
>> D0304 23:15:41.640162650 501457 dns_resolver_ares.cc:624] Using ares
>> dns resolver
>> D0304 23:15:41.640230087 501457 certificate_provider_registry.cc:33]
>> registering certificate provider factory for "file_watcher"
>> D0304 23:15:41.640236782 501457 lb_policy_registry.cc:42] registering
>> LB policy factory for "cds_experimental"
>> D0304 23:15:41.640241375 501457 lb_policy_registry.cc:42] registering
>> LB policy factory for "xds_cluster_impl_experimental"
>> D0304 23:15:41.640258747 501457 lb_policy_registry.cc:42] registering
>> LB policy factory for "xds_cluster_resolver_experimental"
>> D0304 23:15:41.640262652 501457 lb_policy_registry.cc:42] registering
>> LB policy factory for "xds_cluster_manager_experimental"
>> [2022-03-04T23:15:41+10:00] [workflow_client] [info] [process 501457,
>> thread 501457] gRPC client at localhost:4500 is registering with the
>> server...
>> I0304 23:15:41.640909979 501458 subchannel.cc:945] subchannel
>> 0x55e6713dcea0 {address=ipv6:[::1]:4500,
>> args=grpc.client_channel_factory=0x55e6713d6a20,
>> grpc.default_authority=localhost:4500,
>> grpc.internal.subchannel_pool=0x55e6713bb810,
>> grpc.primary_user_agent=grpc-c++/1.44.0-dev,
>> grpc.resource_quota=0x55e6713d7b40, grpc.server_uri=dns:///localhost:4500}:
>> connect failed: {"created":"@1646399741.640833261","description":"Failed to
>> connect to remote host: Connection
>> refused","errno":111,"file":"/home/hoover/workspace/DPAV/Linux/OpenSource/gRPC-focal/src/core/lib/iomgr/tcp_client_posix.cc","file_line":200,"os_error":"Connection
>>
>> refused","syscall":"connect","target_address":"ipv6:[::1]:4500"}
>> [2022-03-04T23:15:41+10:00] [workflow_client] [info] [process 501457,
>> thread 501457] ... gRPC client at localhost:4500 successfully registered
>> with server
>> I0304 23:15:41.642209150 501462 server_builder.cc:327] Synchronous
>> server. Num CQs: 1, Min pollers: 1, Max Pollers: 2, CQ timeout (msec): 10000
>> I0304 23:15:41.642437546 501462 socket_utils_common_posix.cc:353]
>> TCP_USER_TIMEOUT is available. TCP_USER_TIMEOUT will be used thereafter
>> [2022-03-04T23:15:41+10:00] [workflow_client] [info] [process 501457,
>> thread 501457] JobClient client constructed.
>> [2022-03-04T23:15:41+10:00] [workflow_client] [info] [process 501457,
>> thread 501457] HelloWorld client constructed.
>> [2022-03-04T23:15:41+10:00] [workflow_client] [info] [process 501457,
>> thread 501457] New id assigned:
>> localhost:4502:598ec6d9-8a75-4500-b34f-9cab3160c642
>> [2022-03-04T23:15:41+10:00] [workflow_client] [info] [process 501457,
>> thread 501457] Client localhost:4502:598ec6d9-8a75-4500-b34f-9cab3160c642
>> is trying to register client for job type: : hello_world
>> [2022-03-04T23:15:41+10:00] [workflow_client] [info] [process 501457,
>> thread 501463] Client localhost:4502:598ec6d9-8a75-4500-b34f-9cab3160c642
>> registered with Job Server 4501
>> [2022-03-04T23:15:41+10:00] [workflow_client] [info] [process 501457,
>> thread 501457] Client localhost:4502:598ec6d9-8a75-4500-b34f-9cab3160c642
>> received ACK for RegisterNewClient.
>> [2022-03-04T23:15:41+10:00] [workflow_client] [info] [process 501457,
>> thread 501484] Client localhost:4502:598ec6d9-8a75-4500-b34f-9cab3160c642
>> identified JSON message as issueNewJob.
>> [2022-03-04T23:15:41+10:00] [workflow_client] [info] [process 501457,
>> thread 501484] Client localhost:4502:598ec6d9-8a75-4500-b34f-9cab3160c642
>> accepted job.
>> [2022-03-04T23:15:41+10:00] [workflow_client] [info] [process 501457,
>> thread 501484] Client localhost:4502:598ec6d9-8a75-4500-b34f-9cab3160c642
>> acknowledged the job.
>> [2022-03-04T23:15:42+10:00] [workflow_client] [info] [process 501457,
>> thread 501485] Client localhost:4502:598ec6d9-8a75-4500-b34f-9cab3160c642
>> identified JSON message as jobProgressUpdateAck.
>> [2022-03-04T23:15:42+10:00] [workflow_client] [info] [process 501457,
>> thread 501484] Client localhost:4502:598ec6d9-8a75-4500-b34f-9cab3160c642
>> received ACK for final JobProgressUpdate.
>> [2022-03-04T23:15:42+10:00] [workflow_client] [info] [process 501457,
>> thread 501484] Client localhost:4502:598ec6d9-8a75-4500-b34f-9cab3160c642
>> finished processing a job and now shutting down.
>> D0304 23:15:42.482888232 501484 chttp2_transport.cc:1715] ipv4:
>> 127.0.0.1:56916: Sending goaway
>> err={"created":"@1646399742.482860742","description":"Server
>> shutdown","file":"/home/hoover/workspace/DPAV/Linux/OpenSource/gRPC-focal/src/core/lib/surface/server.cc","file_line":481,"grpc_status":0}
>>
>> On Monday, February 14, 2022 at 1:37:12 PM UTC+10 Anh Tran wrote:
>>
>>> Hi team,
>>>
>>> Yes. that is the case. I am also confused...
>>>
>>>
>>> On Saturday, February 12, 2022 at 9:00:29 AM UTC+10 veb...@google.com
>>> wrote:
>>>
>>>> Hi Ahn,
>>>>
>>>> Thanks for the stack trace but I'm a bit confused. Is this what you got
>>>> while your program was stuck waiting forever? It looks a bit off because
>>>> Valgrind complains about "Conditional jump or move depends on
>>>> uninitialised
>>>> value" and callstack appears to show some deadline inside.
>>>>
>>>> On Thursday, February 10, 2022 at 1:10:12 AM UTC-8 Anh Tran wrote:
>>>>
>>>>> Hi @google.com,,
>>>>>
>>>>> Thanks for getting back to me at this. Please see my stack trace from
>>>>> valgrind:
>>>>>
>>>>> ==287419== Memcheck, a memory error detector
>>>>> ==287419== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et
>>>>> al.
>>>>> ==287419== Using Valgrind-3.18.1 and LibVEX; rerun with -h for
>>>>> copyright info
>>>>> ==287419== Command:
>>>>> /home/atran/codes/workflow_client/dist/workflow/job_client_cli --job-type
>>>>> slam
>>>>> ==287419== Parent PID: 287418
>>>>> ==287419==
>>>>> ==287419== Conditional jump or move depends on uninitialised value(s)
>>>>> ==287419== at 0x91743A: void** NextStackFrame<true, false>(void**,
>>>>> void const*, unsigned long, unsigned long) (in
>>>>> /home/atran/codes/workflow_client/dist/workflow/job_client_cli)
>>>>> ==287419== by 0x916F98: int UnwindImpl<false, false>(void**, int*,
>>>>> int, int, void const*, int*) (in
>>>>> /home/atran/codes/workflow_client/dist/workflow/job_client_cli)
>>>>> ==287419== by 0x916D8D: absl::lts_20211102::GetStackTrace(void**,
>>>>> int, int) (in
>>>>> /home/atran/codes/workflow_client/dist/workflow/job_client_cli)
>>>>> ==287419== by 0x90F27C: absl::lts_20211102::(anonymous
>>>>> namespace)::GetStack(void**, int) (in
>>>>> /home/atran/codes/workflow_client/dist/workflow/job_client_cli)
>>>>> ==287419== by 0x924569:
>>>>> absl::lts_20211102::synchronization_internal::GraphCycles::UpdateStackTrace(absl::lts_20211102::synchronization_internal::GraphId,
>>>>>
>>>>> int, int (*)(void**, int)) (in
>>>>> /home/atran/codes/workflow_client/dist/workflow/job_client_cli)
>>>>> ==287419== by 0x90F342:
>>>>> absl::lts_20211102::DeadlockCheck(absl::lts_20211102::Mutex*) (in
>>>>> /home/atran/codes/workflow_client/dist/workflow/job_client_cli)
>>>>> ==287419== by 0x90F84C:
>>>>> absl::lts_20211102::DebugOnlyDeadlockCheck(absl::lts_20211102::Mutex*)
>>>>> (in
>>>>> /home/atran/codes/workflow_client/dist/workflow/job_client_cli)
>>>>> ==287419== by 0x90FB6E: absl::lts_20211102::Mutex::Lock() (in
>>>>> /home/atran/codes/workflow_client/dist/workflow/job_client_cli)
>>>>> ==287419== by 0x8A3AD0: gpr_mu_lock (in
>>>>> /home/atran/codes/workflow_client/dist/workflow/job_client_cli)
>>>>> ==287419== by 0x7DFA25: begin_worker(grpc_pollset*,
>>>>> grpc_pollset_worker*, grpc_pollset_worker**, long) (in
>>>>> /home/atran/codes/workflow_client/dist/workflow/job_client_cli)
>>>>> ==287419== by 0x7DFFDA: pollset_work(grpc_pollset*,
>>>>> grpc_pollset_worker**, long) (in
>>>>> /home/atran/codes/workflow_client/dist/workflow/job_client_cli)
>>>>> ==287419== by 0x7716F4: pollset_work(grpc_pollset*,
>>>>> grpc_pollset_worker**, long) (in
>>>>> /home/atran/codes/workflow_client/dist/workflow/job_client_cli)
>>>>> ==287419== Uninitialised value was created by a stack allocation
>>>>> ==287419== at 0x1C3FD0:
>>>>> Emesent::GRPCQueue::Stub::Register(grpc::ClientContext*, Emesent::Empty
>>>>> const&, Emesent::RegistrationResponse*) (in
>>>>> /home/atran/codes/workflow_client/dist/workflow/job_client_cli)
>>>>> ==287419==
>>>>> ==287419== Thread 7 grpcpp_sync_ser:
>>>>> ==287419== Conditional jump or move depends on uninitialised value(s)
>>>>> ==287419== at 0x916F7F: int UnwindImpl<false, false>(void**, int*,
>>>>> int, int, void const*, int*) (in
>>>>> /home/atran/codes/workflow_client/dist/workflow/job_client_cli)
>>>>> ==287419== by 0x916D8D: absl::lts_20211102::GetStackTrace(void**,
>>>>> int, int) (in
>>>>> /home/atran/codes/workflow_client/dist/workflow/job_client_cli)
>>>>> ==287419== by 0x90F27C: absl::lts_20211102::(anonymous
>>>>> namespace)::GetStack(void**, int) (in
>>>>> /home/atran/codes/workflow_client/dist/workflow/job_client_cli)
>>>>> ==287419== by 0x924569:
>>>>> absl::lts_20211102::synchronization_internal::GraphCycles::UpdateStackTrace(absl::lts_20211102::synchronization_internal::GraphId,
>>>>>
>>>>> int, int (*)(void**, int)) (in
>>>>> /home/atran/codes/workflow_client/dist/workflow/job_client_cli)
>>>>> ==287419== by 0x90F342:
>>>>> absl::lts_20211102::DeadlockCheck(absl::lts_20211102::Mutex*) (in
>>>>> /home/atran/codes/workflow_client/dist/workflow/job_client_cli)
>>>>> ==287419== by 0x90F84C:
>>>>> absl::lts_20211102::DebugOnlyDeadlockCheck(absl::lts_20211102::Mutex*)
>>>>> (in
>>>>> /home/atran/codes/workflow_client/dist/workflow/job_client_cli)
>>>>> ==287419== by 0x90FB6E: absl::lts_20211102::Mutex::Lock() (in
>>>>> /home/atran/codes/workflow_client/dist/workflow/job_client_cli)
>>>>> ==287419== by 0x8A3AD0: gpr_mu_lock (in
>>>>> /home/atran/codes/workflow_client/dist/workflow/job_client_cli)
>>>>> ==287419== by 0x5121A4: grpc_cq_begin_op(grpc_completion_queue*,
>>>>> void*) (in /home/atran/codes/workflow_client/dist/workflow/job_client_cli)
>>>>> ==287419== by 0x5199C4:
>>>>> grpc_core::Server::ShutdownAndNotify(grpc_completion_queue*, void*) (in
>>>>> /home/atran/codes/workflow_client/dist/workflow/job_client_cli)
>>>>> ==287419== by 0x51CD63: grpc_server_shutdown_and_notify (in
>>>>> /home/atran/codes/workflow_client/dist/workflow/job_client_cli)
>>>>> ==287419== by 0x231AA2:
>>>>> grpc::Server::ShutdownInternal(gpr_timespec) (in
>>>>> /home/atran/codes/workflow_client/dist/workflow/job_client_cli)
>>>>> ==287419== Uninitialised value was created by a stack allocation
>>>>> ==287419== at 0x1D37E0: std::_Function_handler<void
>>>>> (std::__cxx11::basic_string<char, std::char_traits<char>,
>>>>> std::allocator<char> > const&, std::__cxx11::basic_string<char,
>>>>> std::char_traits<char>, std::allocator<char> > const&),
>>>>> workflow_client::GRPCIcomm::start_and_wait()::{lambda(std::__cxx11::basic_string<char,
>>>>>
>>>>> std::char_traits<char>, std::allocator<char> > const&,
>>>>> std::__cxx11::basic_string<char, std::char_traits<char>,
>>>>> std::allocator<char> > const&)#1}>::_M_invoke(std::_Any_data const&,
>>>>> std::__cxx11::basic_string<char, std::char_traits<char>,
>>>>> std::allocator<char> > const&, std::__cxx11::basic_string<char,
>>>>> std::char_traits<char>, std::allocator<char> > const&) (in
>>>>> /home/atran/codes/workflow_client/dist/workflow/job_client_cli)
>>>>> ==287419==
>>>>>
>>>>> In case this is interesting, this is how I start my server and wait
>>>>> until shutdown:
>>>>>
>>>>> std::string server_addr_and_port = base_address_ + ":" + id_;
>>>>> grpc::ServerBuilder server_builder;
>>>>> server_builder.AddListeningPort(server_addr_and_port, grpc::
>>>>> InsecureServerCredentials());
>>>>>
>>>>> GRPCQueueImpl grpc_queue_service;
>>>>> server_builder.RegisterService(&grpc_queue_service);
>>>>> server_ = server_builder.BuildAndStart();
>>>>> server_->Wait();
>>>>> On Thursday, February 10, 2022 at 9:08:39 AM UTC+10 ctmah...@gmail.com
>>>>> wrote:
>>>>>
>>>>>> I have also experienced the same issue in my work environment. Our
>>>>>> work around was to have N second timeout and check a shutdown flag and
>>>>>> then
>>>>>> call shutdown.
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Feb 9, 2022 at 3:54 PM, <veb...@google.com' via grpc.io> wrote:
>>>>>>
>>>>>> Would you capture the call-stack when Shutdown function appears to
>>>>>> hang?
>>>>>>
>>>>>> On Wednesday, February 2, 2022 at 10:24:14 PM UTC-8 Anh Tran wrote:
>>>>>>
>>>>>>> The last commit on my local copy of gRPC is 06 Jan 2022, so not that
>>>>>>> old.
>>>>>>> On Thursday, February 3, 2022 at 4:51:16 AM UTC+10 Easwar
>>>>>>> Swaminathan wrote:
>>>>>>>
>>>>>>>> Has anyone of y'all seen this in a more recent version of gRPC.
>>>>>>>> `1.30.2` is really old.
>>>>>>>>
>>>>>>>> On Tuesday, February 1, 2022 at 12:15:54 AM UTC-8 Prasanta Behera
>>>>>>>> wrote:
>>>>>>>>
>>>>>>>>> No, I've not found any solution yet! I was trying to have a
>>>>>>>>> hello-world kind of example to reproduce to open a ticket, but as you
>>>>>>>>> said
>>>>>>>>> with such simple examples it never reproduces...
>>>>>>>>>
>>>>>>>>> On Tuesday, February 1, 2022 at 1:42:43 PM UTC+5:30 Anh Tran wrote:
>>>>>>>>>
>>>>>>>>>> I should also add that this behavior happens during threading.
>>>>>>>>>>
>>>>>>>>>> On Tuesday, February 1, 2022 at 3:45:04 PM UTC+10 Anh Tran wrote:
>>>>>>>>>>
>>>>>>>>>>> Unfortunately I came across the same problem.
>>>>>>>>>>> When trying to isolate the problem (having a simple hello world
>>>>>>>>>>> server-client), the problem seems to go away, i.e server can be
>>>>>>>>>>> shut down.
>>>>>>>>>>>
>>>>>>>>>>> But when using in my own project, this happens. And despite my
>>>>>>>>>>> effort to track down the problem, I can't seem to spot one.
>>>>>>>>>>> This is weird since this version of Shutdown should force shut
>>>>>>>>>>> down after a certain period, as describe in the doc.
>>>>>>>>>>>
>>>>>>>>>>> Prasanta, do you happen to find the solution to your problem?
>>>>>>>>>>> Maybe it will give a hint to mine.
>>>>>>>>>>>
>>>>>>>>>>> On Thursday, January 20, 2022 at 10:02:43 PM UTC+10 Prasanta
>>>>>>>>>>> Behera wrote:
>>>>>>>>>>>
>>>>>>>>>>>> gRPC version : 1.30.2 (c++)
>>>>>>>>>>>> $ gcc --version
>>>>>>>>>>>> gcc (Ubuntu 5.4.0-6ubuntu1~16.04.12) 5.4.0 20160609
>>>>>>>>>>>>
>>>>>>>>>>>> We use gRPC is synchronous mode and stop our gRPC services
>>>>>>>>>>>> with this code
>>>>>>>>>>>>
>>>>>>>>>>>> m_server->Shutdown(std::chrono::system_clock::now() +
>>>>>>>>>>>> std::chrono::seconds(1));
>>>>>>>>>>>> m_server->Wait();
>>>>>>>>>>>>
>>>>>>>>>>>> On rare occasions (about once in 1000 tries) the Shutdown() call
>>>>>>>>>>>> does NOT return and the process just hangs.
>>>>>>>>>>>>
>>>>>>>>>>>> Is there anything I missing to have a reliable shutdown of the
>>>>>>>>>>>> server?
>>>>>>>>>>>>
>>>>>>>>>>> --
>>>>>> You received this message because you are subscribed to the Google
>>>>>> Groups "grpc.io" group.
>>>>>> To unsubscribe from this group and stop receiving emails from it,
>>>>>> send an email to grpc-io+u...@googlegroups.com.
>>>>>> To view this discussion on the web visit
>>>>>> https://groups.google.com/d/msgid/grpc-io/96350454-3e52-4068-b3e1-1fea25537098n%40googlegroups.com
>>>>>>
>>>>>> <https://groups.google.com/d/msgid/grpc-io/96350454-3e52-4068-b3e1-1fea25537098n%40googlegroups.com?utm_medium=email&utm_source=footer>
>>>>>> .
>>>>>>
>>>>>>
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