Previously we specified the period and calculated the cutoff time
in the function. Passing it in means we can run the method multiple
times and avoid getting "new" notifications to time out in the time
it takes to process each batch.
Previously most of the assertions were being run *before* we had
actually called the function. There was also a redundant block of
assertions that just asserted the initial state of the test data.
We have been running in to the problem in
pallets/flask-sqlalchemy#518 where
our page loads very slow when viewing a single page of notifications
for a service in the admin app. Tracing this back and using SQL
explain analyze I can see that getting the notifications takes about
a second but the second query to count how many notifications there
are (to work out if there is a next page of pagination) can take up
to 100 seconds.
As suggested in that issue, we do the pagination ourselves.
Our pagination doesn't need us to know exactly how many notifications
there are, just whether there are any on the next page and that can
be done without running the slow query to count how many
notifications in total by using `count_pages=False`.
This commit is analagous to
c68d1a2f23
The only difference is that in that case, the pagination links are
used to show prev and/or next links in the admin app. In this case,
the pagination links are only used to see if there is a page 2, and
if there is, say that we are only showing the first 50 results.
In response to [1].
[1]: https://github.com/alphagov/notifications-api/pull/3383#discussion_r759379988
It turns out the code that inspired this new alert - in the old
"timeout-sending-notifications" task - was actually redundant as
we already have a task to "replay" notifications still in "created",
which is much better than just alerting about them.
It's possible the replayed notifications will also fail, but in
both cases we should see some kind of error due to this, so I don't
think we're losing anything by not having an alert.
This will log an error when email or SMS notifications have been
stuck in 'created' for too long - normally they should be 'sending'
in seconds, noting that we have a goal of < 10s wait time for most
notifications being processed our platform.
In the next commits we'll decouple similar functionality from the
existing 'timeout-sending-notifications' task.
TLDR: Don't return as many services, and only return their IDs and not
the whole service objects.
Context:
the delete notifications nightly task has been taking longer and longer,
and to delete all three notification types in sequence it now takes up
to 8 hours.
This is because we were retrieving all services, loading them into
memory on the worker, and then trying to delete notifications for each
service in turn.
While it does use a fair chunk of IOPS/CPU on our postgres db, we're not
anywhere close to capacity on those (20% CPU, 4k IOPS out of 30k max)[1]
The real issue appears to be that the task is CPU bound on the periodic
worker - we see the worker spike up to 100% CPU regularly across the
whole 3am-11am period.
We also noticed that for each notification type the task first processes
services with custom data retention (not many but some of the biggest
users), then deals with all other services. We can see from looking at
kibana that, for example, the task starts at 3am, and the custom data
retention service email deletions are finished by 3:12am. The rest of
the emails don't get deleted until 5am, so we knew that the problem is
with how it handles the other services.
There are currently 17000 services in the database. On a typical day,
~800 services will have notifications that are over 7 days old and need
to be deleted. By only returning these services, we reduce the amount of
data transfer and serialisation that needs to happen. It takes about two
minutes to retrieve the distinct service ids from the notifications
table for sms notifications, but that is only 5% the size of the full
list so cuts down on a lot of processing
Also, by only returning service_ids rather than the whole `Service`
model we avoid sqlalchemy needing to do lots of data serialisation, when
we were only using the `Service.id` field from that result anyway.
[1] https://admin.cloud.service.gov.uk/organisations/55b1eb7d-e4c5-4359-9466-dd3ca5b0e457/spaces/80d769ff-7b01-49a4-9fa4-f87edd5328f9/services/6093d337-6918-4b97-9709-97529114eb90/metrics
[2] https://grafana-paas.cloudapps.digital/d/_GlGBNbmk/notify-apps?orgId=2&refresh=5s&var-space=production&var-app=notify-delivery-worker-periodic&from=now-24h&to=now
[3] https://kibana.logit.io/s/9423a789-282c-4113-908d-0be3b1bc9d1d/app/kibana#/discover?_g=(refreshInterval:(display:Off,pause:!f,value:0),time:(from:now-24h,mode:quick,to:now))&_a=(columns:!(message),index:'logstash-*',interval:auto,query:(query_string:(analyze_wildcard:!t,query:'%22Deleting%20email%20notifications%20for%20services%20without%20flexible%20data%20retention%22')),sort:!('@timestamp',desc))
For preview and staging environments, we often send no messages
in a single day. This is currently causing a `DivisionByZero` error
that is rendering the page with no results. This makes it impossible
to look at preview/staging and see if the performance page is
working correctly or not.
(psycopg2.errors.DivisionByZero) division by zero
[SQL: SELECT CAST(ft_processing_time.bst_date AS TEXT) AS date, ft_processing_time.messages_total AS ft_processing_time_messages_total, ft_processing_time.messages_within_10_secs AS ft_processing_time_messages_within_10_secs, (ft_processing_time.messages_within_10_secs / CAST(ft_processing_time.messages_total AS FLOAT)) * %(param_1)s AS percentage
FROM ft_processing_time
WHERE ft_processing_time.bst_date >= %(bst_date_1)s AND ft_processing_time.bst_date <= %(bst_date_2)s ORDER BY ft_processing_time.bst_date]
[parameters: {'param_1': 100, 'bst_date_1': datetime.date(2021, 11, 12), 'bst_date_2': datetime.date(2021, 11, 19)}]
(Background on this error at: http://sqlalche.me/e/14/9h9h)
I've fixed this by falling back to 100.0% for days we send
no messages. Maybe some argument that it should be N/A rather than
100% but I think it doesn't really matter as this is only
going to affect preview and staging as we will never have a day
sending no messages in production.
People with dyslexia and dyscalculia find it difficult to transpose
codes which have consecutive, repeated digits[1].
This commits enhances the algorithm for generating codes to not repeat
the previous digit in a code.
This reduces the key space for our codes from 100,000 possibilities to
65,610 possibilities.
1. https://twitter.com/annaecook/status/1442567679710150662
This is necessary until:
- The Admin app is using the new "areas(_2)" format to store and
retrieve data.
- We've migrated all existing broadcast messages to use the new
format.
Note that "areas" / "ids" isn't actually used for anything except
printing out the PagerDuty message - it's not sent to the proxy [1].
[1]: 6edc6c70aa/app/celery/broadcast_message_tasks.py (L190-L193)
Regardless of channel.
Do not include:
- broadcasts older than 25.05.2021
- stubbed broadcasts
- broadcasts that were not transmitted. So only broadcasting,
cancelled and completed make the list;
Last year we had an issue with the daily limit cache and the query that was populating it. As a result we have not been checking the daily limit properly. This PR should correct all that.
The daily limit cache is not being incremented in app.notifications.process_notifications.persist_notification, this method is and should always be the only method used to create a notification.
We increment the daily limit cache is redis is enabled (and it is always enabled for production) and the key type for the notification is team or normal.
We check if the daily limit is exceed in many places:
- app.celery.tasks.process_job
- app.v2.notifications.post_notifications.post_notification
- app.v2.notifications.post_notifications.post_precompiled_letter_notification
- app.service.send_notification.send_one_off_notification
- app.service.send_notification.send_pdf_letter_notification
If the daily limits cache is not found, set the cache to 0 with an expiry of 24 hours. The daily limit cache key is service_id-yyy-mm-dd-count, so each day a new cache is created.
The best thing about this PR is that the app.service_dao.fetch_todays_total_message_count query has been removed. This query was not performant and had been wrong for ages.
The query had a group by on notification_type and notification_status, this not only slows the query down but is wrong. The query only looked at the first result, but this query would return as many rows as different notification types and status, meaning the results do not include the correct number.
Are we concerned that all status types are included. For example letters can be cancelled or have validation-failures which shouldn't be included in the daily limit check.
This adds total_letters to the data that is returned by the
`/platform-stats/data-for-billing-report` endpoint so that we can add
total letters as a column in the CSV file that can be downloaded.
The trouble is the aggregate query to return the big blue numbers on the dashboard and /notifications/{notification_type} page is taking too long to return.
I have some ideas on how to improve the query, but should take some time to do some more research and test. In the meantime, let's just ignore "todays" total numbers for the high volume services. There are only two services that this will affect.
- sqlalchemy.sql.expression.case must include an else statement.
- clearly define list of columns for inbound_sms_history insert, getting the list from InboundSmsHistory.__table__.c was causing data type errors.
- remove relationships when not needed, the foreign key relationship is established in the creation of the column. This will get rid of the warnings referenced here: http://sqlalche.me/e/14/qzyx.
- update queries now that he user relationship in ServiceUser db model has been removed.
- move the check that a template is archived to the view instead of the dao method. The check was clearing the session before the version history could be done.
Deleting notifications in the night tasks still needs to be
investigated. The raw sql is causing an error.
- sqlalchemy.sql.expression.case must include an else statement.
- clearly define list of columns for inbound_sms_history insert, getting the list from InboundSmsHistory.__table__.c was causing data type errors.
- remove relationships when not needed, the foreign key relationship is established in the creation of the column. This will get rid of the warnings referenced here: http://sqlalche.me/e/14/qzyx.
- update queries now that he user relationship in ServiceUser db model has been removed.
- move the check that a template is archived to the view instead of the dao method. The check was clearing the session before the version history could be done.
Deleting notifications in the night tasks still needs to be
investigated. The raw sql is causing an error.
Introduce a contextmanger function to handle exceptions and nested
transactions. Using the nested_transaction will start a
nested transaction with `db.session.begin_nested`, once the nested
transaction is complete the commit will happen.
`@transactional` has been updated to commit unless in a nested
transaction.
db update/insert.
Using a savepoint for the multiple transactions allows us to rollback if
there is an error when executing the second db transaction.
However, this does add a bit of complexity. Developers need to manage
the db session when calling multiple nested tranactions.
Unit tests have been added to test this functionality and some end to
end tests have been done to make sure all transactions are rollback if
there is an exception while executing the transaction.
the default free allowance for the organisation type.
The update/insert for the default free allowance is done in a separate
transaction. Updates to services need to happen in a transaction to
trigger the insert into the ServicesHistory table. For that reason the
call to set_default_free_allowance_for_service is done after the service
is updated.
I've added a try/except around the set_default_free_allowance_for_service call to ensure we still get the update to the service but get an exception log if the update to annual_billing fails. I believe it's important to preserve the update to the service in the unlikely event that the annual_billing upsert fails.
April 1 2021.
In this PR there is a command to set annual_billing for all active
services with the the new defaults.
The new method `set_default_free_allowance_for_service` will also be
called in a PR to follow that will set a services free allowance to the
default if the organisation for the service is changed.
Names of services and orgs were confusing, and variable setting
was done in a way that made it easy to introduce errors.
Now hopefully it is more readable and more error-proof.
This is not required by DVLA and since [1] we no longer care about
the end of letter filenames when collating them, so removing it is
safe to do. Note that the name of the ZIP files of collated letters
is based on a hash of the filenames, which needed updating in tests.
Before merging this we need to do a test run in Staging, so DVLA can
check that a mixture of the old / new filenames won't cause issues.
[1]: https://github.com/alphagov/notifications-api/pull/3172
Previously we did some unnecessary work:
- Collate task. This had one S3 request to get a summary of the object,
which was then used in another request to get the full object. We only
need the size of the object, which is included in the summary [1].
- Archive task. This had one S3 request to get a summary of the object,
which was then used to make another request to delete it. We still need
both requests, but we can remove the S3.Object in the middle.
[1]: https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/s3.html#objectsummary
Previously we made a call to S3 to list objects for a letter, even
though we already had the precise key of the single object to hand.
This removes the one usage of "get_s3_bucket_objects" and uses the
filename directly in the call to remove the object.
Previously we generated the filename we expected a letter PDF to be
stored at in S3, and used that to retrieve it. However, the generated
filename can change over the course of a notification's lifetime e.g.
if the service changes from crown ('.C.') to non-crown ('.N.').
The prefix of the filename is stable: it's based on properties of the
notification - reference and creation - that don't change. This commit
changes the way we interact with letter PDFs in S3:
- Uploading uses the original method to generate the full file name.
The method is renamed to 'generate_' to distinguish it from the new one.
- Downloading uses a new 'find_' method to get the filename using just
its prefix, which makes it agnostic to changes in the filename suffix.
Making this change helps to decouple our code from the requirements DVLA
have on the filenames. While it means more traffic to S3, we rely on S3
in any case to download the files. From experience, we know S3 is highly
reliable and performant, so don't anticipate any issues.
In the tests we favour using moto to mock S3, so that the behaviour is
realistic. There are a couple of places where we just mock the method,
since what it returns isn't important for the test.
Note that, since the new method requires a notification object, we need
to change a query in one place, the columns of which were only selected
to appease the original method to generate a filename.
We no longer will send them any stats so therefore don't need the code
- the code to work out the nightly stats
- the performance platform client
- any configuration for the client
- any nightly tasks that kick off the sending off the stats
We will require a change in cronitor as we no longer will have this task
run meaning we need to delete the cronitor check.
