Re: [PATCH v12 04/20] index-helper: new daemon for caching index and related stuff

> On 06/26/2016 04:53 AM, Eric Wong wrote:
> >David Turner <novalis@novalis.org> wrote:
> >>On 06/25/2016 10:33 AM, Duy Nguyen wrote:
> >>>>+               /*
> >>>>+                * Our connection to the client is blocking since a client
> >>>>+                * can always be killed by SIGINT or similar.
> >>>>+                */
> >>>>+               set_socket_blocking_flag(client_fd, 0);
> >>>
> >>>Out of curiosity, do we really need this? I thought default behavior
> >>>was always blocking (and checked linux kernel, it seemed to agree with
> >>>me). Maybe for extra safety because other OSes may default to
> >>>something else?
> >>
> >>Yes -- see this bug report for details:
> >>https://bugs.python.org/issue7995
> >
> >I realize it's an issue with BSDs, but it still seems
> >unnecessary, here:
> >
> >1) the packet_read => get_packet_data => read_in_full => xread
> >    call chain already poll()s on EAGAIN/EWOULDBLOCK.
> >    write_in_full => xwrite busy loops on EAGAIN/EWOULDBLOCK.
> >    xwrite should probably poll, too; but I guess EAGAIN is
> >    uncommon with small writes.
> 
> That is a CPU-burning busy loop on a non-blocking socket.