On Dec 14 2007 15:39, James Nichols wrote: > >However, after approximately 38 hours of operation, all outbound >connection attempts get stuck in the SYN_SENT state. It happens >instantaneously, where I go from the baseline of about 60-80 sockets >in SYN_SENT to a count of 200 (corresponding to the # of java threads >that make these calls). > >When I stop and start the Java application, all the new outbound - ^
at that point, try tcpdump. It may, or may not, show something. >connections still get stuck in SYN_SENT state. >During this time, I am still able to SSH to the box Try uploading something through rsync+ssh, or scp+ssh. If it aborts or hangs after a while, that may be an strong indication of a crappy router. Also, I'd advise to upgrade to something newer like >= 2.6.22. There was one of those SACK-broken routers around here too, but it seemed to have been replaced (or linux got a mysterious fix :-) as one day when I tried turning off SACK, rsync didnot abort anymore on new connections. Though, if SACK was the problem, the problem would be much more likely to appear after the handshake. YMMV. >and run wget to Google, cnn, etc, so the >problem appears to be specific to the hosts that I'm accessing via the >webservices. > >For a long time, the only thing that would resolve this was rebooting >the entire machine. Once I did this, the outbound connections could >be made succesfully. However, very recently when I had once of these >incidents I disabled tcp_sack via: > >echo "0" > /proc/sys/net/ipv4/tcp_sack > >And the problem almost instanteaously resolved itself and outbound >connection attempts were succesful. I hadn't attempted this before >because I assumed that if any of my network >equipment or remote hosts had a problem with SACK, that it would never >work. In my case, it worked fine for about 38 hours before hitting a >wall where no outbound connections could be made. > >I'm running kernel 2.6.18 on RedHat, but have had this problem occur >on earlier kernel versions (all 2.4 and 2.6). -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
