Investigate ActionMailer::MailDeliveryJob for being killed by Linux OOM killer
This worker seems to be consuming a lot of memory. It is listed in top offending workers by sum total of allocated bytes, that consume more than 1 GB
Also, this worker has large percentage of the number of scheduled but not completed/failed jobs in jobs_enqueued/jobs_completed.
Note: workers that were killed by Linux OOM killer doesn't have job_status: failed.
Assumption
A lot of Markdown or content could take a lot of memory to render.
Edited by Nikola Milojevic