I just got it to reproduce. Here are the last ~3,000 lines of the debug output: https://gist.github.com/RyanGordon/e3d211a6430daac560296a4b301f121b
At the end, it seemed like all of the requests timed out, so we called ` grpc_call_cancel_with_status <https://github.com/quizlet/grpc/blob/hhvm-bz2/src/php/ext/grpc/hhvm/call.cpp#L568>` to clean the request up. After we call that, we call ` grpc_completion_queue_pluck <https://github.com/quizlet/grpc/blob/hhvm-bz2/src/php/ext/grpc/hhvm/call.cpp#L572>` (justification <https://github.com/grpc/grpc/pull/12306#issuecomment-330337644>) with an infinite timeout so it gets stuck there forever. After about 4 minutes of nothing happening, gRPC reports a "Socket closed" error, but nothing after that. The one line that sticks out to me is L2677 from the gist. Typically `grpc_call_combiner_stop()` gets called right after that line but not in this case and then the behavior shown in the logs look atypical after that. On Wednesday, September 20, 2017 at 12:57:35 PM UTC-7, Sree Kuchibhotla wrote: > > Yes, GRPC_VERBOSITY=DEBUG. > > On Wed, Sep 20, 2017 at 12:10 PM, ryan via grpc.io < > [email protected] <javascript:>> wrote: > >> 1) Yep, will do - I should continue to run with GRPC_VERBOSITY=DEBUG >> right? >> 2) Just merged latest master through >> >> >> On Wednesday, September 20, 2017 at 9:32:54 AM UTC-7, Sree Kuchibhotla >> wrote: >>> >>> The line does look a bit suspicious to me (It means the combiner >>> has 30597 closures - which is a lot - the least significant bit in "last" >>> is ignored - the actual count is stored in the remaining bits) >>> >>> D0919 14:54:36.312349629 51030 combiner.c:163] >>> C:0x7f54faf35c00 grpc_combiner_execute c=0x7f4c22edbfb0 last=61995 >>> >>> Not sure why we ran in to this situation. Putting that aside for now, >>> based on the logs (in the failed case), the threads are waiting for the >>> batch to complete >>> >>> I0919 14:54:36.312170818 51030 call.c:2069] >>> grpc_call_start_batch(call=0x7f4c22edb020, ops=0x7f550e39fde0, nops=4, tag= >>> *0x7f4c22edb020*, reserved=(nil)) >>> I0919 14:54:36.312199708 51030 call.c:1677] ops[0]: >>> SEND_INITIAL_METADATA >>> .. >>> I0919 14:54:36.312210605 51030 call.c:1677] ops[1]: >>> RECV_INITIAL_METADATA ptr=0x7f4c22e9e510 >>> I0919 14:54:36.312214004 51030 call.c:1677] ops[2]: >>> SEND_MESSAGE ptr=0x7f4c262df200 >>> I0919 14:54:36.312216804 51030 call.c:1677] ops[3]: >>> SEND_CLOSE_FROM_CLIENT >>> .. >>> D0919 14:54:36.312362846 51030 completion_queue.c:812] PENDING >>> TAGS: *0x7f4c22edb020* >>> >>> >>> The real reason to look here is why isn't the call making any progress >>> (I am assuming the sends are successful but the receives aren't coming) - >>> In other words, I think the threads are waiting in epoll_wait and cv_wait >>> because there is nothing incoming on the fds. >>> >>> 1) Could you turn on the "tcp" traces as well? : i.e export GRPC_TRACE >>> = "tcp,api,call_combiner,op_failure,client_channel" >>> 2) Could you sync to the latest HEAD ? (we did fix a few bugs recently >>> in timers and the polling engine very recently.. want to make sure you are >>> on the latest HEAD. Based on the line numbers in callstacks, looks like >>> your branch is a few days behind) >>> >>> >>> thanks, >>> Sree >>> >>> PS: >>> >> Hmm so it looks like the reason why grpc_combiner_continue_exec_ctx >>> doesn't get called is because exec_ctx->active_combiner is actually NULL >>> and so the function just returns false. Not yet sure why / how that became >>> NULL >>> This happens when we executed all the closures on the combiner .. so >>> this may be a red-herring (maybe not..but I it would help to look at tcp >>> traces first) >>> >>> >>> >>> On Tue, Sep 19, 2017 at 4:58 PM, ryan via grpc.io < >>> [email protected]> wrote: >>> >>>> >>>> Hmm so it looks like the reason why grpc_combiner_continue_exec_ctx >>>> doesn't get called is because exec_ctx->active_combiner is actually NULL >>>> and so the function just returns false. Not yet sure why / how that became >>>> NULL >>>> >>>> >>>> On Tuesday, September 19, 2017 at 9:55:10 AM UTC-7, [email protected] >>>> wrote: >>>>> >>>>> Err... Actually I just realized that my source files had changed so >>>>> that stack isn't entirely accurate. Here is a proper stack trace: >>>>> >>>>> #0 0x00007f6ddb4a1a82 in pthread_cond_timedwait@@GLIBC_2.3.2 () from >>>>>> /lib64/libpthread.so.0 >>>>>> #1 0x00007f6dcbf4471c in gpr_cv_wait (cv=0x7f6db13f8a90, >>>>>> mu=0x7f6a65b9cd90, abs_deadline=...) at >>>>>> src/core/lib/support/sync_posix.c:80 >>>>>> #2 0x00007f6dcbe9bea8 in begin_worker (pollset=0x7f6a65b9cd90, >>>>>> worker=0x7f6db13f8a70, worker_hdl=0x0, now=0x7f6db13f8a30, deadline=...) >>>>>> at >>>>>> src/core/lib/iomgr/ev_epoll1_linux.c:747 >>>>>> #3 0x00007f6dcbe9c7c9 in pollset_work (exec_ctx=0x7f6db13f8b80, >>>>>> ps=0x7f6a65b9cd90, worker_hdl=0x0, now=..., deadline=...) at >>>>>> src/core/lib/iomgr/ev_epoll1_linux.c:941 >>>>>> #4 0x00007f6dcbea9691 in grpc_pollset_work (exec_ctx=0x7f6db13f8b80, >>>>>> pollset=0x7f6a65b9cd90, worker=0x0, now=..., deadline=...) at >>>>>> src/core/lib/iomgr/ev_posix.c:210 >>>>>> #5 0x00007f6dcbecc1a8 in cq_next (cq=0x7f6a65b9cc80, deadline=..., >>>>>> reserved=0x0) at src/core/lib/surface/completion_queue.c:914 >>>>>> #6 0x00007f6dcbecc5d2 in grpc_completion_queue_next >>>>>> (cq=0x7f6a65b9cc80, deadline=..., reserved=0x0) at >>>>>> src/core/lib/surface/completion_queue.c:992 >>>>>> #7 0x00007f6dcc394ecc in HPHP::c_Call_ni_startBatch >>>>>> (this_=0x7f6a9288a670, actions=...) at >>>>>> /opt/build/hhvm/grpc/src/php/ext/grpc/hhvm/call.cpp:583 >>>>> >>>>> >>>>> and >>>>> >>>>> #0 0x00007f6dd56b6d43 in epoll_wait () from /lib64/libc.so.6 >>>>>> #1 0x00007f6dcbe9b9e5 in do_epoll_wait (exec_ctx=0x7f6d99ff8b80, >>>>>> ps=0x7f6a65867710, now=..., deadline=...) at >>>>>> src/core/lib/iomgr/ev_epoll1_linux.c:640 >>>>>> #2 0x00007f6dcbe9c972 in pollset_work (exec_ctx=0x7f6d99ff8b80, >>>>>> ps=0x7f6a65867710, worker_hdl=0x0, now=..., deadline=...) at >>>>>> src/core/lib/iomgr/ev_epoll1_linux.c:964 >>>>>> #3 0x00007f6dcbea9691 in grpc_pollset_work (exec_ctx=0x7f6d99ff8b80, >>>>>> pollset=0x7f6a65867710, worker=0x0, now=..., deadline=...) at >>>>>> src/core/lib/iomgr/ev_posix.c:210 >>>>>> #4 0x00007f6dcbecc1a8 in cq_next (cq=0x7f6a65867600, deadline=..., >>>>>> reserved=0x0) at src/core/lib/surface/completion_queue.c:914 >>>>>> #5 0x00007f6dcbecc5d2 in grpc_completion_queue_next >>>>>> (cq=0x7f6a65867600, deadline=..., reserved=0x0) at >>>>>> src/core/lib/surface/completion_queue.c:992 >>>>>> #6 0x00007f6dcc394ecc in HPHP::c_Call_ni_startBatch >>>>>> (this_=0x7f6a624e0670, actions=...) at >>>>>> /opt/build/hhvm/grpc/src/php/ext/grpc/hhvm/call.cpp:583 >>>>> >>>>> >>>>> These are both proper examples of it just timing out on >>>>> epoll_wait/pthread_cond_timedwait. >>>>> >>>>> The other thing I've noticed is on the bad request: >>>>> >>>>>> >>>>>> D0919 14:54:36.312349629 51030 combiner.c:163] C:0x7f54faf35c00 >>>>>> grpc_combiner_execute c=0x7f4c22edbfb0 *last=61995* >>>>> >>>>> >>>>> last is 61995 which seems to indicate the number of scheduled items in >>>>> the queue. In a normal request this number is kept low. >>>>> >>>>> On Tuesday, September 19, 2017 at 9:19:11 AM UTC-7, Michael Lumish >>>>> wrote: >>>>>> >>>>>> It looks like your stack trace includes a call to >>>>>> grpc_server_request_registered_call with a NULL server. That is >>>>>> suspicious. >>>>>> >>>>>> On Tue, Sep 19, 2017 at 8:41 AM ryan via grpc.io < >>>>>> [email protected]> wrote: >>>>>> >>>>>>> >>>>>>> Hello all - >>>>>>> >>>>>>> I've been developing a gRPC-HHVM extension >>>>>>> <https://github.com/grpc/grpc/pull/11553>. In the process of stress >>>>>>> testing this extension we've consistently seen a condition where gRPC >>>>>>> gets >>>>>>> into a state where any request that is made gets indefinitely stuck on >>>>>>> the >>>>>>> epoll_wait syscall (or times out if a timeout is set on >>>>>>> grpc_completion_queue_next). Everything works fine and is chugging >>>>>>> along >>>>>>> and then this problem happens and all of the requests get >>>>>>> stuck/timeout. >>>>>>> This is what it looks like in gdb: >>>>>>> >>>>>>> Thread 21 (Thread 0x7f54f6bff700 (LWP 51033)): >>>>>>> >>>>>>> #0 0x00007f554ad90d43 in epoll_wait () from /lib64/libc.so.6 *<-- >>>>>>> indefinitely stuck or times out if one is set* >>>>>>> >>>>>>> #1 0x00007f55416969e5 in add_poll_object (exec_ctx=0x2482ad88, >>>>>>> bag=0x188924, bag_type=(POLL_OBJ_POLLSET | unknown: 32596), item=0x0, >>>>>>> item_type=(POLL_OBJ_POLLSET | unknown: 1097427428)) at >>>>>>> src/core/lib/iomgr/ev_epollsig_linux.c:1484 >>>>>>> >>>>>>> #2 0x00007f5541697972 in fd_ref (fd=0x4, reason=0x33b8b87c0 >>>>>>> <Address 0x33b8b87c0 out of bounds>, file=0x0, line=0) at >>>>>>> src/core/lib/iomgr/ev_poll_posix.c:447 >>>>>>> >>>>>>> #3 0x00007f55416a4691 in tcp_drop_uncovered_then_handle_write >>>>>>> (exec_ctx=0x7f54f6bf8680, arg=0x7f4c4e2c9010, error=0x0) at >>>>>>> src/core/lib/iomgr/tcp_posix.c:239 >>>>>>> >>>>>>> #4 0x00007f55416c71a8 in grpc_server_request_registered_call >>>>>>> (server=0x0, rmp=0x0, call=0x2482ad88, deadline=0x188924, >>>>>>> initial_metadata=0x7f4c4e2c8f00, optional_payload=0x0, >>>>>>> cq_bound_to_call=0x4, cq_for_notification=0x33b8b87c0, >>>>>>> >>>>>>> tag=0x0) at src/core/lib/surface/server.c:1486 >>>>>>> >>>>>>> >>>>>>> #5 0x00007f55416c75d2 in conforms_to (slice=..., >>>>>>> legal_bits=0x7f4c22ce2e50 "\270\064\245\214L\177", >>>>>>> err_desc=0x7f54f6bf8701 >>>>>>> "\211\030") at src/core/lib/surface/validate_metadata.c:40 >>>>>>> >>>>>>> #6 0x00007f5541b97105 in HPHP::c_Call_ni_startBatch >>>>>>> (this_=0x7f4c22ce2e60, actions=...) at >>>>>>> /home/ryangordon/hhvm/grpc/src/php/ext/grpc/hhvm/call.cpp:529 >>>>>>> >>>>>>> >>>>>>> The stack trace doesn't always look like that but it always is stuck >>>>>>> on epoll_wait/epoll_pwait often from gpr_cv_wait. >>>>>>> >>>>>>> >>>>>>> I've managed to get GPRC_TRACE=all GRPC_VERBOSITY=DEBUG of a good >>>>>>> request and a request when it is in the bad state to compare side by >>>>>>> side. >>>>>>> >>>>>>> >>>>>>> Good Request: >>>>>>> https://gist.githubusercontent.com/RyanGordon/831a8213e735bb1a4e5b93a854aab3c8/raw/7e37d595dbe56a77274bff83b64ab661a80e0c27/Not-Frozen%2520Log%2520Snippet >>>>>>> >>>>>>> Bad Request: >>>>>>> https://gist.githubusercontent.com/RyanGordon/831a8213e735bb1a4e5b93a854aab3c8/raw/7e37d595dbe56a77274bff83b64ab661a80e0c27/Frozen%2520log%2520snippet >>>>>>> >>>>>>> >>>>>>> The bad request looks like this when it's execution deviates: >>>>>>> >>>>>>> >>>>>>> D0919 14:54:36.312349629 51030 combiner.c:163] >>>>>>> C:0x7f54faf35c00 grpc_combiner_execute c=0x7f4c22edbfb0 last=61995 >>>>>>> D0919 14:54:36.312353011 51030 exec_ctx.c:73] closure >>>>>>> 0x7f4c22edbec0 finished >>>>>>> I0919 14:54:36.312358626 51030 completion_queue.c:834] >>>>>>> grpc_completion_queue_next(cq=0x7f4c22e9e200, deadline=gpr_timespec { >>>>>>> tv_sec: 4, tv_nsec: 999000000, clock_type: 3 }, reserved=(nil)) >>>>>>> >>>>>>> ... >>>>>>> >>>>>>> >>>>>>> Whereas, the good request does this: >>>>>>> >>>>>>> D0915 15:19:50.178995777 13689 combiner.c:163] >>>>>>> C:0x7f932172f700 grpc_combiner_execute c=0x7f9313d67fb0 last=1 >>>>>>> D0915 15:19:50.179005880 13689 exec_ctx.c:73] closure >>>>>>> 0x7f9313d67ec0 finished >>>>>>> D0915 15:19:50.179074826 13689 combiner.c:225] >>>>>>> C:0x7f932172f700 grpc_combiner_continue_exec_ctx contended=0 >>>>>>> exec_ctx_ready_to_finish=1 time_to_execute_final_list=0 >>>>>>> D0915 15:19:50.179077765 13689 combiner.c:243] >>>>>>> C:0x7f932172f700 maybe_finish_one n=0x7f9313d67fb0 >>>>>>> >>>>>>> ... (and a whole lot more) >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> Effectively it seems like the something is not getting scheduled when >>>>>>> it should be (grpc_combiner_continue_exec_ctx never gets run). I've >>>>>>> been working on this for a few weeks now and haven't been able to track >>>>>>> down why or a fix. I have the full logs if they might be helpful. I've >>>>>>> been testing on my branch that is kept pretty close to grpc/grpc master. >>>>>>> >>>>>>> >>>>>>> Does anyone have any idea what is going on? I have the bad process open >>>>>>> on a test server in gdb and have timeouts implemented so I can run >>>>>>> repeated requests at it to continue debugging if necessary. >>>>>>> >>>>>>> >>>>>>> Thanks, >>>>>>> >>>>>>> Ryan >>>>>>> >>>>>>> -- >>>>>>> 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 [email protected]. >>>>>>> To post to this group, send email to [email protected]. >>>>>>> Visit this group at https://groups.google.com/group/grpc-io. >>>>>>> To view this discussion on the web visit >>>>>>> https://groups.google.com/d/msgid/grpc-io/b3cc406f-9b93-4259-b8f9-df3eb904132a%40googlegroups.com >>>>>>> >>>>>>> <https://groups.google.com/d/msgid/grpc-io/b3cc406f-9b93-4259-b8f9-df3eb904132a%40googlegroups.com?utm_medium=email&utm_source=footer> >>>>>>> . >>>>>>> For more options, visit https://groups.google.com/d/optout. >>>>>>> >>>>>> -- >>>> 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 [email protected]. >>>> To post to this group, send email to [email protected]. >>>> Visit this group at https://groups.google.com/group/grpc-io. >>>> To view this discussion on the web visit >>>> https://groups.google.com/d/msgid/grpc-io/d8cd586a-d329-4a51-a030-fff17c458e7d%40googlegroups.com >>>> >>>> <https://groups.google.com/d/msgid/grpc-io/d8cd586a-d329-4a51-a030-fff17c458e7d%40googlegroups.com?utm_medium=email&utm_source=footer> >>>> . >>>> >>>> For more options, visit https://groups.google.com/d/optout. >>>> >>> >>> -- >> 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 [email protected] <javascript:>. >> To post to this group, send email to [email protected] >> <javascript:>. >> Visit this group at https://groups.google.com/group/grpc-io. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/grpc-io/0924073e-285e-444e-aa95-b500dbb34320%40googlegroups.com >> >> <https://groups.google.com/d/msgid/grpc-io/0924073e-285e-444e-aa95-b500dbb34320%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> >> For more options, visit https://groups.google.com/d/optout. >> > > -- You received this message because you are subscribed to the Google Groups "grpc.io" group. 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