closesocket() call on socket in windows takes 20 sec

Question

I'm trying to close socket on windows from closesocket(), but it takes 20 sec to complete. at first I thought it was about linger interval, although I was not setting anything with setsockopt by linger, so I added such code:

linjer lobj;
lobj.l_onoff = 1;
lobj.l_linger = 0;

sz = sizeof(lobj);

setsockopt(s_, SOL_SOCKET, SO_LINGER, (char *) &lobj, sz);

but it still does not help.

any ideas? I just want to close connection, doesnt matter if its gracefull or abortion, just want to close it as soon as possible.

P.S. it takes exactly 20 sec.

lobj.l_onoff = 1; 
lobj.l_linger = 0; 
sz = sizeof(lobj); 
setsockopt(s_, SOL_SOCKET, SO_LINGER, (char *) &lobj, sz);
lobj.l_onoff = -1;
lobj.l_linger = -1; 
getsockopt(s_, SOL_SOCKET, SO_LINGER, (char *) &lobj, &sz); 
log << "Option 1:" << lobj.l_linger << ".\n"; 
log << "Option 2:" << lobj.l_onoff << ".\n";
closesocket(s_);

this code prints option1 = 0 and option2 = 1, so it really sets option correctly.

Also, observing from wireshark, it sends RST at the beginning of whole delay.

plus, closesocket() returns 0.

P.S. I have set SO_REUSADDR, can it be causing it?

Please including complete working code that shows the issue. — Richard, Jan 29 '15 at 15:19
Unfortunately I can not, I can answer any question but cannot paste code, sorry about that — Zhani Baramidze, Jan 29 '15 at 15:20
yes, as I said before adding this code I was not setting anything with setsockopt, so it was l_onoff=0, I checked with getsockopt also — Zhani Baramidze, Jan 29 '15 at 15:34
If it's a TCP socket: do you call shutdown(SD_BOTH) on the socket? Otherwise the socket implementation might have to wait until all data is sent and no further data is received on the connection. — rpress, Jan 29 '15 at 16:21
it should not wait, I turned on linger with timeout of 0, so it just sends RST packet — Zhani Baramidze, Jan 29 '15 at 18:32
@rpress That's not correct, and calling `shutdown()` wouldn't fix it if it was. — user207421, Jan 29 '15 at 19:36

score 1 · Answer 1 · answered Jan 29 '15 at 19:34

1

If you can't post the code you can't ask the question here. Those are the rules.

However the only way closesocket() can take any measurable time at all is if:

there is a lot of pending outgoing data, and
you have set a positive SO_LINGER timeout.

You can only get a delay of 20 seconds by setting a positive SO_LINGER timeout of >= 20 seconds and having a lot of pending outgoing data and probably a peer that isn't reading.

If you had left SO_LINGER strictly alone, which you should, or set it to false, or true with a zero timeout, closesocket() is asynchronous and returns immediately, and in the latter case you would also have reset the connection.

Ergo either you haven't done what you claimed or your observations are faulty. Possibly it is the final send() which is blocking.

It would be interesting to know whether this closesocket() call returned -1 and if so what the error value was.

answered Jan 29 '15 at 19:34

user207421

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whole code that is using that socket is quite big, I can post only those parts that are interesting to us :) – Zhani Baramidze Jan 29 '15 at 19:49
Please post your code *in your question.* You can see for yourself that it is completely and utterly illegible when posted in comments. I'm not even gong to even try to decipher that mess. – user207421 Jan 29 '15 at 19:50
sorry about that. yes, I'm not sure but I think peer isn't reading data, it may be that some data is being retransmitted but I want to close that connection, without waiting for anything. – Zhani Baramidze Jan 29 '15 at 19:56
Sure you're closing the same socket you set abortive LINGER on? – user207421 Jan 29 '15 at 20:02
yes, after that code comes closesocket(s_) – Zhani Baramidze Jan 29 '15 at 20:12
I also attached gdb when its stuck, last 2 frames are from ntdll!zwclose() – Zhani Baramidze Jan 29 '15 at 20:14

closesocket() call on socket in windows takes 20 sec

1 Answers1