Messages in this thread | | | Date | Wed, 19 Dec 2007 18:07:24 +0100 | From | Eric Dumazet <> | Subject | Re: After many hours all outbound connections get stuck in SYN_SENT |
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James Nichols a écrit : >> So you see outgoing SYN packets, but no SYN replies coming from the remote >> peer ? (you mention ACKS, but the first packet received from the remote >> peer should be a SYN+ACK), > > Right, I meant to say SYN+ACK. I don't see them coming back.
So... Really unlikely a linux problem, but ...
> > >> When the problem comes, instead of restarting the application, please take a >> tcpdump of say 10.000 packets. >> Then turn off tcp_sack and take a 2nd tcpdump sample, and make both samples >> available to us. > > I can take these captures and take a look at the results. > Unfortunately, I don't think I'll be able to make the captures > available to the general public.
I dont understand, why dont you change IPs to mask them with 192.168.X.Y, or just ME, and peer1, peer2, peer...
> > > >> If turning off tcp_sack makes the problem go away, why dont you turn it off >> all the time ? > > Unfortunately, I think that will be the answer if I can't get any help > fixing this problem in the kernel. It's a bummer, because many of the > remote hosts my application communicates with are on wireless links, > so there may be performance implications to turning SACK off. >
Random ideas :
1) Is your server behind a NET router or something ? 2) Are you sure you are not using connection tracking, and hit a limit on it ?
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