Messages in this thread | | | Date | Tue, 18 Dec 2007 19:32:26 +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 : >> Here is a purely hypothethical (and in practice unlikely) idea: >> Java opens up too many sockets (more than you really request) and the >> kernel, for whatever reason, does not deliver packets to programs >> which have maxed out their fds. Well it would already help if the >> java blob was split into multiple blobs (assuming the problem >> persists), as the best testcase is the smallest possible one. So if >> it is reproducable without the web blob, great step there. >> >> > > > Right, I don't disagree with you there. FWIW, I can disable entire > parts of the application and have already narrowed down reproduction > of this issue to the 200 threads that make the webservice calls, so it > doesn't have anything to do with any of the GUI or other background > services that my application executes. > > > You said: > > >> Well you could still blame Java. I am sure that if you program was C, >> the problem could be narrowed down much easier. >> > > I'm curious to know how this problem would be easier to narrow down if > it were written in C. > Well... please dont start a flame war :(
Back to your SYN_SENT problem, I suppose the remote IP is known, so you probably could post here the result of a tcdpump ?
tcpdump -p -n -s 1600 host IP_of_problematic_peer -c 500
Most probably remote peer received too many attempts from you, and a anti DOS mechanism is droping all SYN packets.
Ah well... I remember now that you mentioned tcp_sack setting had an effect, so forget the "Most probably..." and give some tcpdump traces :)
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