Two issues here:
1. The maintainer would repeatedly try to shrink the ready queue
each time it woke up during a low memory condition. This has
been fixed to trigger whenever we transition to low memory
instead.
2. At some point during refactoring, we dropped the save part
of the message shrinking processing, so we'd only successfully
shrink messages that had previously been saved and stored to
spool. Messages that we deferred spooling, or otherwise modified
post reception, would not be saved and thus not be eligible to
shrink.
Ideally we'd have an integration test for this, but it is a bit awkward
because we'd need to contrive an appropriate ulimit for just this
instance and generate appropriate load to trip over that limit. I don't
fancy the chances that such a test wouldn't be flakey.
My ad-hoc test procedure was:
ulimit -m 2028527
./target/release/kumod --policy simple_policy.lua
then in another window:
./target/release/traffic-gen --target 127.0.0.1:2025 --body-size 100000 --duration 3600 --throttle 15000/s --http
the generator will eventially experience load shedding http responses,
and you can see the shrink procedure triggering in the kumod output.
curl -s 'http://127.0.0.1:8000/metrics' | grep memory
can also be used to check the usage, limit and how many times it trips.
You can also use smtp for this, but the smtp client in traffic gen will
try hard to reconnect without telling you about the shortage, so you
will need to look at the metrics to see it happening.
At the lower level, expose an options struct that allows control
over how various checks and conditions are reported out of the
attempt to load the set of shaping files.
Expose a separate list of errors, distinct from warnings.
Each check can either be ignored, a warning, or an error.
Errors cause validate-shaping and --validate mode to exit
with an error condition, whilst warnings are simply emitted
as informational items.
In the shaping helper, it is possible to configure a separate set of
options for the main live service and validation mode, which allows you
to run a more relaxed configuration by default, but be a bit more strict
in your pre-commit and pre-deploy configuration validation pipeline
refs: https://github.com/KumoCorp/kumomta/issues/287
This commit addresses a couple of related issues around scheduled qeueue
suspensions:
1. There was no check in the ready queue logic to confirm that a
given message was not part of a suspension. Ideally, it wouldn't
land in the ready queue if it is suspended, but if you have a large
ready queue and one of the messages generates a suspension, then
the remainder would get attempted, oblivious to the new suspension.
The resolution here is to add a check for that case, log a transfail
and requeue the message.
2. We only checked whether the scheduled queue was suspended in the
case where a message was being newly inserted into the queuing
system. Importantly, messages being promoted from the scheduled
queue didn't use this code path. This commit fixes this up by
relocating the check to the appropriate location. In addition,
we now will log a transfail for this case and delay the message
according to its retry schedule.
3. Since we're in here changing the retry schedule for suspensions,
take the opportunity to take care of #293 which applies to the
more general logic around all sources being suspended.
The upshot of this is that we're now logging transfails in a number
of suspension cases where we weren't previously, and using the normal
retry schedule for those cases where we weren't previously doing
that either.
refs: https://github.com/KumoCorp/kumomta/issues/290
refs: https://github.com/KumoCorp/kumomta/issues/293
* When using very small file size or duration constraints, we might
attempt to create multiple file segments in the same second. Since
we require exclusive creation access to the log file name, the
subsequent attempts to open the segment would fail with a permission
denied error and cause the associated log record to be dropped.
Add the number of fractional seconds to the log file name to
avoid this.
* When using small durations and low traffic, we wouldn't expire log
files until we had processed 10k records. That's not so bad in
a production setting, but in the test harness it is problematic.
We now check for expiration as part of the file size check so
that we will prune a segment that is at its time limit.
I don't expect either of these conditions to crop up and matter
in a production setting.
I've added a note to the breaking changes section of the changelog
about the addition of the fractional seconds to the log file name.
I don't expect that to impact anyone in practice either, but I
wanted to call it out as a potential difference in case someone
is using a very precise regex/glob to match the file names.
Failure to connect to a proxy server will now include more context
about the proxy server and protocol in the error message, and
will bump a counter.
Failure to directly bind a source address for the outgoing connection
will bump a counter.
refs: https://github.com/KumoCorp/kumomta/issues/286
This really is adding batching support to custom lua delivery
protocol handlers, but the main use case for these today is
to implement log hooks.
The way that it works is that you can specify a `batch_size`
as part of setting up the lua protocol handler.
Then, when it is time to send messages, if the batch_size is
the default of 1, the lua delivery logic will invoke the `send` method
on the connection object returned from the constructor. This
is the same as the behavior from before this commit.
However, if the batch_size is greater than 1, then the lua delivery
logic will instead attempt to collect up to batch_size messages
that are immediately available from the ready queue, and then pass
those to a new `send_batch` method.
The send_batch method accepts an array of messages; that array will
always have at least one message, and up to batch_size messages,
depending on the throughput and queue size.
If the send_batch method's return value applies equally to all
messages in the batch, so if it indicates that something failed,
that disposition will apply to all messages.
One of the reasons that I'd avoided implementing batching thus far
was that it makes it awkward to resolve persistent/recurring issues
that are due to a single message in that batch. If the batch is
always retried together then there is a good chance that it will
always fail together.
There's no explicit mitigation for that issue here, but it may
be probablistically mitigated by the jitter that is applied to
messages that transiently fail. If a batch transiently fails,
each message in that batch will be subject to its own random
jitter which should cause an offending message to be retried
with a different subset of messages next time around.
The integration test included here demonstrates the batching
working with an http log hook implementation.
Sites with lots of tenants and campaigns would produce an overwhelming
amount of output with the default json output mode.
Let's make json opt-in and default to a human readable output
mode that is more concise.
```console
$ kcli bounce-list
ID REASON REMAIN BOUNCED CRITERIA
0d2402cc-2dce-44c8-85f6-a4c056300f55 boingo 4m 31s 150ms 560us 575ns 10,990 domain=hotmail.com
```
In systems with very large numbers of queues, it will take an
effectively unbounded amount of time to produce the initial
summary of results if we were to wait for the bounce to be
applied to every queue.
Let's adjust the output of the kcli to indicate that it is async,
and update the docs which already suggested that the numbers would
be partial to indicate that you can only really consume the id
from the response.
Following on from the previous commit, there were two cases where
we'd pick up the unicode human readable version of a punycode encoded
domain name instead of the retaining the punycode text.
One for the domain_name field, and the other for the synthesized
set of MX hosts that we create when the domain has no explicit
A records in its DNS.
This commit fixes that.
There's big explanation about this in the included docs change.
The TL;DR is: we can now optionally queue the request and generate it
asynchronously wrt. the incoming injection request.
There's also a throttle that can be used to constrain this, because
the asynchronous submission disconnects the injection request from
any kind of back pressure that we'd otherwise have to indicate to
the injector that there might be load related issues.
Previously, we would deterministically produce the list of hosts
and use the same thing for each session that we established outbound.
This could result in biasing the outgoing traffic onto a single host
and result in lower overall throughput.
This commit shuffles the set of hosts at a given preference level
to probabalistically distribute the load among them.
When splitting the config across multiple files, we should not
raise an error if the base or domain section is missing from
the file that is currently being processed.
Let's also show which file is currently being processed.
This commit adds a couple of options that make it a bit easier
to make sense of high traffic environments.
It also fixes an issue with displaying timing: previously, if
we'd never seen the official start of a session, we'd never
show a reasonable time delta, and every record for that session
would be reported as `0ns`.
Now we assume that the first record for a session is as good as
the starting time for the session. That allows us to show
some meaningful timing information in the case that we attach
to an in-flight session for which we missing the start.
This enables shaping based on MX hostname and domain name matching
rules.
At a lower level, this is supported via two new options:
additional_connection_limits and additional_message_rate_throttles that
allow specifying arbitrarily scoped named limits and throttles, which
in addition to allowing provider-based rules in the shaping helper,
allow things like global or other more esoteric scoping of constraints.
closes: https://github.com/KumoCorp/kumomta/pull/260
This commit adds a background task that periodically evaluates
a glob expression that defaults to the recommended configuration
location and filename suffixes, and a set of additional paths
to observe.
Whenever the hash of that combined set of files changes it causes the
ConfigEpoch to increment and broadcast to subscribers that the
configuration has changed in some fashion.
The QueueConfig struct has a new refresh_strategy which can select
between the earlier Ttl based refresh for the queue config, or
the new Epoch refresh.
When the epoch changes, the config refresh task will cause each of
the scheduled queues that is using the Epoch strategy to re-evaluate
the get_queue_config event to update their configuration.
The queues helper sets the refresh strategy to Epoch.
A new HTTP endpoint has been added: it can force a bump in the
current epoch, effectively causing all epoch subscribers to
wake up and perform a refresh.
These changes avoid doing O(number-of-scheduled-queues) get_queue_config
callouts every refresh_interval; instead, the work is performed only
when an appropriate change is detected or triggered.
Mike Hillyer
Wez Furlong
tommairs