Symfony Messenger Demonstration

This application is a simple messenger demonstration. Saving a text for either Wintermute or Neuromancer is made slow on purpose. Instead of Saving directly in the controller (as done in /naive), the /wintermute and /neuromancer endpoints use Symfony messenger to not block the web process.

You can open /stats in a web browser to see what is going on. That page refreshes itself automatically.

To generate a bunch of messages to see the queues in action, there is a command app:generate-messages.

Setup

You need docker with docker-compose. Start the system with

make up

On first run, you nedd to initialize the database with

make database
make migration

And get a command line in the container with

make shell

Usage

In order to ingest the data, you need to run the message workers. Run this Symfony command and choose the queue you want to consume from:

bin/console messenger:consume -vv

To run workers in parallel, I installed GNU parallel into the docker container. Specify the queue name to the yes command and the number of parallel workers you want with the -j flag to parallel:

yes wintermute | parallel -j 10 --line-buffer bin/console messenger:consume

You can specify any flags to messenger:consume as usual, e.g. -vv to see what messages are processed, or the rejuvenation controls.

This will just keep running forever, and parallel should lead to having exactly the specified number of workers running. It will start a new worker each time a worker exits for whatever reason.

In a real system, you would want to run this process with a supervisor to restart yes and parallel itself, should they crash. Or use an actual dynamic task scheduler that adjusts workers depending on on queue size.