Troubleshooting notifications

Metabase is failing to send notifications like alerts or dashboard subscriptions.

Root cause:

When long running queries get stuck in the queue, they can block all other queries from running.

Steps to take:

1. Increase the notification thread pool size with the MB_NOTIFICATION_THREAD_POOL_SIZE environment variable and reboot the server.

For example, you can set the thread pool size to 10 by setting the environment variable: MB_NOTIFICATION_THREAD_POOL_SIZE=10.

Note: remember that Metabase won’t pick up old failed tasks so you will see the effect of this change in the next notification period.