Celery: Can I execute one instance of a function at a time using Celery?

Question

So I have a program that for example runs functions: x, y, z. Let's say that execution time for the functions is:

x -> 5 seconds
y -> 15 minutes
z -> 2 minutes

So, I'm facing a problem where when y is being executed, and I get another task for y, it also starts executing y again. So i'll have 2 y's being executed at the same time.

What I'm trying to achieve? Y being executed only once at a time. Once the first Y execution finishes, the second Y can start getting executed.

I tried looking for solutions and what I found was documentation that would let us execute one task at a time (x / y / z) however I want all of the task to be executed normally, just when we get 2 instances of y, we need the second instance to wait for the first instance to finish executing.

So we need the queue to look like: (working)

X
Y -> Y
Z

The solutions I found would make it like:

X-> Y-> Z -> Y, which is only one task at a time, doesn't matter which function.

Which is NOT what I'm looking for.

Please let me know if the question was not clear.

Thank you.

Answer 1

Yes, it is doable and is explained in the Ensuring a task is only executed one at a time section of the "Task Cookbook" part of the Celery documentation.