On Mon, Mar 31, 2008 at 11:33 AM, Leo <neleo@xxxxxxx> wrote: > Yes, we have changed the back_log settings in my.cnf. We also tried > various combinations of the kernel parameters you mentioned in your > email - without success. > > Have you made any changes on the client (=webserver)? Perhaps it's not a > problem of the server (=mysql). As I figured out in my original posting > it looks as if the client didn't receive the SYN/ACK package from the > server (keep in mind that it is reproducable with lo interface, > therefore it's not a hardware problem with cables, switches, ...): > > "When you look at the TCP pakets transmitted between server and client > (tcpdump) you will see that the client sends a SYN and the server > answers with a SYN/ACK. However the client will never receive the > SYN/ACK. Therefore the client resends a SYN after exactly 3 seconds. The > server answers with a SYN/ACK again and this time the client receives > the paket. Now the connection is working." > Hi! Can you please post that tcpdump? (Just to check the first ACK). Br H.Willstrand > On friday I received an email from another user having the same problem. > As I mentioned in my last email: we are not alone ;-) > > Many thanks for your help. > > Kind regards, > Leo > > > > Marlon de Boer wrote: > > Leo wrote: > > > >> We discovered the same problem two month ago (even 3 sec connect > >> problems between webserver and mysql backend). I have posted it to > >> the list (subject "TCP connect hangs for 3 seconds", 2008-02-04) > >> but didn't get any answer yet. When I read your mail it was a > >> flicker of hope. > >> > >> This is not a mysql issue! You can easily reproduce it with a few > >> lines of C code (see below, it's similar to your program) running > >> against any open port on the server (e.g. netcat: nc -k -l > >> <PORTNUMBER>). We have also tested it on different hardware and > >> kernel versions (up to 2.6.24.4) and we can deliver further > >> information if requested ... > >> > >> Unfortunately the kernel parameter you mentioned in your second > >> mail (net.core.somaxconn) didn't solve the problem. > >> > >> I think there are many other people out there having this problem > >> unconsciously. Can anybody help? > >> > >> > > I used the c code below to test the server side. After playing with > > the kernel settings, some code, > > setsockopt(sd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt)) and > > listen(sd, 8192) the timeouts disappeared. > > > > Did you changed the settings in mysql.cnf? back_log = 8192, and > > restarted the mysql daemon? Else try to raise it to 16384 or even higher. > > > > Regards > > Marlon > > > > > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-net" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-net" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
