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. For more options, visit https://groups.google.com/d/optout.
