Like I said you may just block the EventLoop. Attach profiler and check if the EventLoop is blocked that is used by the SocketChannel.
> On 20. Jul 2017, at 10:42, Ronggen Liu <[email protected]> wrote: > > Thanks, but I'm still confused why the server can't accept the connection > when the TCP 3-way handshake is completed. > > On Thursday, July 20, 2017 at 4:12:31 PM UTC+8, Norman Maurer wrote: > Hey, > > comments inside… > >> On 20. Jul 2017, at 08:50, Ronggen Liu <[email protected] <javascript:>> >> wrote: >> >> Hello, >> >> problem: >> some connections were lost when there are too many clients were trying to >> connect to the server during a short time, for example, send out about 10k >> connections during about 3 seconds. >> >> findings: >> as i know, all the connections would be accepted in method doReadMessage of >> NioServerSocketChannel, and, in fact, we did find out that some connections >> were not accepted from there, but, actually, the TCP have been created >> successfully with completed 3-ways handsharke. >> meanwhile, we found, to some degree, we can avoid this issue by increasing >> the option SO_BACKLOG of ChannelOption, currently, we set it with 8, should >> be a little bit low. > > 8 is most likely a way too low. I would not touch this setting at all if you > not want to increase it to a high-number. > > >> >> questions: >> how to handle this issue? as i know, the client should receive connection >> refused error when the number of the connections exceed the SO_BACKLOG, but >> the client didn't receive it. > > No it will not receive a connect refused error but the connection will just > timeout. You should check if you block the EventLoop somehow and so not be > able to accept fast enough. > > >> >> Thanks, >> Gary >> >> -- >> You received this message because you are subscribed to the Google Groups >> "Netty discussions" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected] <javascript:>. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/netty/3f5aae56-1fd6-4e0b-8a6e-cfed66653c1e%40googlegroups.com >> >> <https://groups.google.com/d/msgid/netty/3f5aae56-1fd6-4e0b-8a6e-cfed66653c1e%40googlegroups.com?utm_medium=email&utm_source=footer>. >> For more options, visit https://groups.google.com/d/optout >> <https://groups.google.com/d/optout>. > > > -- > You received this message because you are subscribed to the Google Groups > "Netty discussions" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected] > <mailto:[email protected]>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/netty/bbccbf19-aa67-4346-83dd-566257893296%40googlegroups.com > > <https://groups.google.com/d/msgid/netty/bbccbf19-aa67-4346-83dd-566257893296%40googlegroups.com?utm_medium=email&utm_source=footer>. > For more options, visit https://groups.google.com/d/optout > <https://groups.google.com/d/optout>. -- You received this message because you are subscribed to the Google Groups "Netty discussions" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/netty/71FA5562-0694-4DE8-A31D-35F6F0467116%40googlemail.com. For more options, visit https://groups.google.com/d/optout.
