This commit reimplements how we monitor Sidekiq processes that are
forked from the Unicorn master process. Prior to this change, we rely on
`Jobs::Heartbeat` to enqueue a `Jobs::RunHeartbeat` job every 3 minutes.
The `Jobs::RunHeartbeat` job then sets a Redis key with a timestamp. In
the Unicorn master process, we then fetch the timestamp that has been set
by the job from Redis every 30 minutes. If the timestamp has not been
updated for more than 30 minutes, we restart the Sidekiq process. The
fundamental flaw with this approach is that it fails to consider
deployments with multiple hosts and multiple Sidekiq processes. A
sidekiq process on a host may be in a bad state but the heartbeat check
will not restart the process because the `Jobs::RunHeartbeat` job is
still being executed by the working Sidekiq processes on other hosts.
In order to properly ensure that stuck Sidekiq processs are restarted,
we now rely on the [Sidekiq::ProcessSet](https://github.com/sidekiq/sidekiq/wiki/API#processes)
API that is supported by Sidekiq. The API provides us with "near real-time (updated every 5 sec)
info about the current set of Sidekiq processes running". The API
provides useful information like the hostname, pid and also when Sidekiq
last did its own heartbeat check. With that information, we can easily
determine if a Sidekiq process needs to be restarted from the Unicorn
master process.
Zeitwerk simplifies working with dependencies in dev and makes it easier reloading class chains.
We no longer need to use Rails "require_dependency" anywhere and instead can just use standard
Ruby patterns to require files.
This is a far reaching change and we expect some followups here.
This reverts commit e805d44965.
We now have mechanisms in place to ensure heartbeat will always
be scheduled even if the scheduler is overloaded per: 098f938b
* FIX: Heartbeat check per sidekiq process
* Rename method
* Remove heartbeat queues of previous bootups
* Regis feedback
* Refactor before_start
* Update lib/demon/sidekiq.rb
Co-Authored-By: Régis Hanol <regis@hanol.fr>
* Update lib/demon/sidekiq.rb
Co-Authored-By: Régis Hanol <regis@hanol.fr>
* Expire redis keys after 3600 seconds
* Don't use redis to store the list of queues
This reduces chances of errors where consumers of strings mutate inputs
and reduces memory usage of the app.
Test suite passes now, but there may be some stuff left, so we will run
a few sites on a branch prior to merging
