1.9.4: TCP queries when some threads are full

[Stuart Henderson]

On 2019-10-21, Wouter Wijngaards via Unbound-users <unbound-users at nlnetlabs.nl> wrote:
>> 
>> I tracked down the file descriptor for one of the TCP connections to
>> unbound, found it was created over 12 hours ago, and then filtered for
>> traffic for the host and port that was holding the connection with
>> tcpdump, and not a single packet appeared for the several minutes I was running
>> it.
>> 
>
> When TCP is nearly full it should use an even shorter timeout.  And not 
> allow such very long idle connections.  That looks like it went wrong.

David Gwynne ran into that as well,
https://nlnetlabs.nl/pipermail/unbound-users/2019-August/011748.html