zlacker

>>hyzyla+(OP)
You really don't need anything fancy to implement a queue using SQL. You need a table with a primary id and a "status" field. An "expired" field can be used instead of the "status". We used the latter because it allows easy retries.

1. SELECT item_id WHERE expire = 0. If this is empty, no items are available.

2. UPDATE SET expire = some_future_time WHERE item_id = $selected_item_id AND expire = 0. Then check whether UPDATE affected any rows. If it did, item_id is yours. If not, loop. If the database has a sane optimizer it'll note at most one document needs locking as the primary id is given.

All this needs is a very weak property: document level atomic UPDATE which can return whether it changed anything. (How weak? MongoDB could do that in 2009.)

Source code at https://git.drupalcode.org/project/drupal/-/blob/9.2.x/core/... (We cooked this up for Drupal in 2009 but I am reasonably sure we didn't invent anything new.)

Of course, this is not the fastest job queue there is but it is quite often good enough.

>>_ugfj+z2
Oh please stop using databases as queues. I spent a disproportionate amount of time in the last 20 years undoing that decision. It doesn’t scale at all well.

>>hughrr+gc
One of my businesses is running a software solution build in 2012. Ever since it is using queuing via a database. It's simple, easy to maintain. And scales really well. We are talking about 10k queues per second. Yes it disattracts developers like you. They usually prefer the latest fancy trending tool. luckily those types are often responsible for overengineering things and overly complex solutions.