powerman
commented
1 week ago Well… This looks like a valid fix, but it's unclear is it good idea to fix this at all - after all current behaviour helps you to find a bug (forgotten close() call).
I do not remember is Perl supports half-closed file handles. If yes, and you'll provide a test case which shows this issue in a real use-case then I agree this issue must be fixed. Such test might work this way:
- client connects to server, sends request, half-closes it socket, then waits for data from server
- server received request, got EOF from a client, and then sends some data to the client every second on that half-closed socket
- server in this case must not use 100% CPU
wangvisual
One of my program has a bug, it forget to call close() after got EOF, then the program use 100% CPU, strace shows it continue to call read():
clock_gettime(CLOCK_MONOTONIC, {tv_sec=2453951, tv_nsec=921150570}) = 0 epoll_wait(4, [{EPOLLIN, {u32=17, u64=21474836497}}], 64, 3416) = 1 clock_gettime(CLOCK_MONOTONIC, {tv_sec=2453951, tv_nsec=921167046}) = 0 read(17, "", 8192) = 0 clock_gettime(CLOCK_MONOTONIC, {tv_sec=2453951, tv_nsec=921183697}) = 0 epoll_wait(4, [{EPOLLIN, {u32=17, u64=21474836497}}], 64, 3416) = 1 clock_gettime(CLOCK_MONOTONIC, {tv_sec=2453951, tv_nsec=921215171}) = 0 read(17, "", 8192) = 0 clock_gettime(CLOCK_MONOTONIC, {tv_sec=2453951, tv_nsec=921232568}) = 0 epoll_wait(4, [{EPOLLIN, {u32=17, u64=21474836497}}], 64, 3416) = 1 clock_gettime(CLOCK_MONOTONIC, {tv_sec=2453951, tv_nsec=921249128}) = 0 read(17, "", 8192) = 0 clock_gettime(CLOCK_MONOTONIC, {tv_sec=2453951, tv_nsec=921265710}) = 0 epoll_wait(4, [{EPOLLIN, {u32=17, u64=21474836497}}], 64, 3416) = 1 clock_gettime(CLOCK_MONOTONIC, {tv_sec=2453951, tv_nsec=921282208}) = 0
undef $self->{_r} can solve this issue: elsif (!$m->{is_eof}) { # EOF delivered only once $m->{is_eof} = 1; $m->EVENT(EOF); $self->{_r} = undef; # add this line }