Previously, the fetchlimit tested the recursive-clients soft limit
that's defined as 90% of the hard limit (the actual configured value).
This worked previously because the reaping of the oldest recursive
client was put on the same event queue as the current TCP client, thus
the cleaning has happened before the new TCP client established a new
connection.
With the change in BIND 9.14 that added a multiple event queues the
cleaning of the oldests clients is no longer synchronous and could
happen stochastically making the soft limit testing fail often. The
situation became even worse with the new networking manager, thus we
change the system test to fail only if the hard limit bound is not
honored.
Changing the accounting of the already reaped TCP clients so the soft
limit testing is possible again is out of the scope for this change.
In the test the quota is set to 400, and softquota to 90%*400=360.
We first attach to quota, and then if we're above softquota we
drop the oldest client. With new socket code and taskmgr it's
parallel enough to create a race between multiple instances doing
'attach to quota' and then 'drop oldest client' - making number
of clients go over softquota. It's not a problem in real life, as
it's just soft quota.
- add CHANGES note
- update copyrights and license headers
- add -j to the make commands in .gitlab-ci.yml to take
advantage of parallelization in the gitlab CI process
3938. [func] Added quotas to be used in recursive resolvers
that are under high query load for names in zones
whose authoritative servers are nonresponsive or
are experiencing a denial of service attack.
- "fetches-per-server" limits the number of
simultaneous queries that can be sent to any
single authoritative server. The configured
value is a starting point; it is automatically
adjusted downward if the server is partially or
completely non-responsive. The algorithm used to
adjust the quota can be configured via the
"fetch-quota-params" option.
- "fetches-per-zone" limits the number of
simultaneous queries that can be sent for names
within a single domain. (Note: Unlike
"fetches-per-server", this value is not
self-tuning.)
- New stats counters have been added to count
queries spilled due to these quotas.
See the ARM for details of these options. [RT #37125]
