On Mon, Aug 14, 2023 at 11:28 AM metronome <xiangdong...@gmail.com> wrote: > > >> If several different goroutines decide to wake up the polling > >> goroutine before the polling goroutine wakes up, they will each write > >> a single byte > > Wondering, with the introduction of "netpollWakeSig", does it still hold > true? Thanks.
Good point, I think you're right. With netpollWakeSig we shouldn't expect to see more than a single byte written to the pipe. Doesn't hurt to try to read more bytes, though. Ian > On Tuesday, July 11, 2023 at 9:00:36 AM UTC+8 Ian Lance Taylor wrote: >> >> On Mon, Jul 10, 2023 at 6:10 AM shaouai <aou...@gmail.com> wrote: >> > >> > In the implementation of the Go netpoller, `netpollBreak()` attempts to >> > write 1 byte to `netpollBreakWr`, whereas `netpoll()` reads up to 16 bytes >> > from `netpollBreakRd`, why 16 bytes rather than 1 byte? >> > >> > write up to 1 byte: >> > https://cs.opensource.google/go/go/+/refs/tags/go1.20.5:src/runtime/netpoll_epoll.go;l=77;drc=c7cc2b94c63af610a29b1b48cfbfb87cb8abf05b >> > >> > read up to 16 bytes: >> > https://cs.opensource.google/go/go/+/refs/tags/go1.20.5:src/runtime/netpoll_epoll.go;l=146;drc=c7cc2b94c63af610a29b1b48cfbfb87cb8abf05b >> >> A single byte will wake up a goroutine sleeping in netpoll, so there >> is no reason to write more than one byte. >> >> If several different goroutines decide to wake up the polling >> goroutine before the polling goroutine wakes up, they will each write >> a single byte, and they will all be satisfied by a single wakeup. >> And, if we don't read all those bytes, there will still be bytes in >> the pipe and we'll wake up the next time around the poll loop even if >> we don't have to. So we try to read all of their wakeup bytes at >> once. The number 16 is arbitrary, based on the assumption that it's >> not all that likely that more than 16 goroutines will try to wake up >> the poller simultaneously. >> >> Ian > > -- > You received this message because you are subscribed to the Google Groups > "golang-nuts" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to golang-nuts+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/golang-nuts/8a3ae80e-1e78-441d-8c9a-c99e94e3c2c9n%40googlegroups.com. -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/CAOyqgcV_NZfFCG8wkcKd%3DGmev-Vsi4mTD4ECdh%3DRdeVRDyWAeg%40mail.gmail.com.
