when rpc client closed by server, the cpu 100%

[hiseyxhp]

when rpc client closed by server, the cpu 100%，the epoll-wait return and evt.events=0
the pstack is
#0 0x00007fcd31b4ade7 in epoll_pwait () from /usr/lib64/libc.so.6
#1 0x00000000007af40e in seastar::reactor_backend_epoll::wait_and_process (this=0x6000002e0000, timeout=, active_sigmask=) at ../../src/core/reactor_backend.cc:652
#2 0x000000000061ece5 in poll_once (this=) at ../../src/core/reactor.cc:2818
#3 operator() (__closure=0x7fff3369a820) at ../../src/core/reactor.cc:2716
#4 std::_Function_handler<bool(), seastar::reactor::run()::<lambda()> >::_M_invoke(const std::_Any_data &) (__functor=...) at /usr/local/include/c++/7.2.0/bits/std_function.h:302
#5 0x000000000064b4fd in operator() (this=0x7fff3369a820) at /usr/local/include/c++/7.2.0/bits/std_function.h:706
#6 seastar::reactor::run (this=0x600000296000) at ../../src/core/reactor.cc:2742
#7 0x000000000060a2e3 in seastar::app_template::run_deprecated(int, char**, std::function<void ()>&&) (this=0x7fff3369ade0, ac=, av=, func=) at ../../src/core/app-template.cc:202
#8 0x0000000000572f56 in main ()

[avikivity]

There is not enough infomation in the bug report. I have no idea what code you are running.

[hiseyxhp]

thank you for your answer! I just run the rpc-test and my system is centos7。
rpc_sample.tar.gz

this is my test project code , when the client connect to the server, and then close the server by Ctrl+C, the client occupy cpu 100%

[avikivity]

I guess no one ran the rpc sample application since it was written.

/cc @gleb-cloudius

[hiseyxhp]

I also test with seastar-18.08.0, this does not have this problem, when use seastar-20.05.0, this problem occured.

[hiseyxhp]

I have look into this question,find that in the file reactor_backend.cc:660。
if (evt.events & (EPOLLHUP | EPOLLERR)) {
// treat the events as required events when error occurs, let
// send/recv/accept/connect handle the specific error.
evt.events = pfd->events_requested;
}
when pfd->events_requested = 0，witch mean all events were handled, this line should lead epoll-event can not remove。this lead the client occupy cpu 100%。