TCP backlog exceeded with bind 9.16.0

[Warren Kumari]

On Mon, Mar 16, 2020 at 1:56 PM Craig Leres
<bind-workers-post at ee.lbl.gov> wrote:
>
> Since 9.14 reaches EOL soon, we recently switch to 9.16. Several times
> since then is has been necessary to restart the zone master named
> because it starts rejecting TCP connections (breaking zone transfers
> among other things). When this happens netstat shows a bunch of
> established connections with no pending data:
>
>      Proto Recv-Q Send-Q Local Address          Foreign Address
> (state)
>      tcp4       0      0 131.243.???.???.53     ???.???.???.???.2223
> ESTABLISHED
>
> And also some non-zero receive queues in close_wait or closed states:
>
>      tcp4      66      0 131.243.???.???.53     ???.???.???.???.37998
> CLOSED
>      tcp4      66      0 131.243.???.???.53     ???.???.???.???.29349
>    CLOSE_WAIT
>
> Finally, the TCP listen queue for named's public ip has more connections
> queued than the TCP backlog:
>
>      Current listen queue sizes (qlen/incqlen/maxqlen)
>      Proto Listen                           Local Address
>      tcp4  16/0/10                          131.243.???.???.53
>
> Which is why new TCP connections are being refused.
>
> Is anybody else seeing this?

This: https://kb.isc.org/docs/operational-notification-an-error-in-handling-tcp-client-quota-limits-can-exhaust-tcp-connections-in-bind-9160

?
W

>
>                 Craig
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> bind-workers at lists.isc.org
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-- 
I don't think the execution is relevant when it was obviously a bad
idea in the first place.
This is like putting rabid weasels in your pants, and later expressing
regret at having chosen those particular rabid weasels and that pair
of pants.
   ---maf