Messenger is the solution for sending messages asynchronously. That is, a notification and recipient are stored in a separate system then dispatched outside a web request. This improves performance of a web request, in both time and memory.

When the Drupal Symfony Messenger project is installed, Notifier will automatically send messages via the Symfony Messenger component.

Running messenger

Ensure your system is executing the messenger command, otherwise your notifications will get stuck unsent.

Local development

For local development, you can run sm messenger:consume asynchronous.

INFO

If vendor binaries have not been added to PATH, you may need to prefix the command, such as vendor/bin/sm or bin/sm depending on your Composer setup.

Production development

For production deployments, running sm messenger:consume asynchronous is preferred. However, if your production infrastructure does not support long-running processes, you can replicate drush cron or drush queue:run behavior where the command exits after a period of time or other criteria by adding flags:

sm messenger:consume asynchronous \
  --limit=256 \ 
  --time-limit=120 \ 
  --memory-limit=128M

Recommended flags:

• --limit — exit after this number of messages have been processed.
• --time-limit — exit after this amount of seconds have passed.
• --memory-limit — exit after this amount of peak memory has been reached.