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Hi, I have a question about concurrency. I have a ...
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i
Hi, I have a question about concurrency. I have a queue with concurrency = 1. Yesterday I manually started a job run via UI and also I have scheduled the same flow to run in 10 hours or so. The manually triggered job didn't finished in 10 hours, so another one shouldn't have started (because concurrency = 1), but it did start. Am I doing something wrong?
c
Is this Prefect 1 or Prefect 2? Are you using tags? How is your concurrency configured?
i
Prefect Cloud. Concurrency configured on a queue level - I have a queue dedicated only for 1 flow. For this queue I set concurrency = 1
Also I added tag limiting concurrency to 1 for each task inside this flow - also didn't help
c
prefect cloud is the cloud offering, not necessarily 1 or 2
there is prefect cloud 1 and prefect cloud 2
i
prefect cloud 2
c
Did you submit the run manually with tags? What about the scheduled one? The concurrency limit should be set on ‘matching’ flows and runs, where matching is decided based on the tags submitted to the agent
i
Tags are written in code, so I guess they are always there
c
when you look at the flow run history, are you able to see the tags in the logs when the flow is submitted
I’m trying to determine when you submit a manual run versus a scheduled run if the tagset matched, which is what the concurrency limit should be keying off of
if they were submitted ot the same agent.
i
Hmm, but when I set concurrency (1) limit on a whole queue (and all runs are inside this queue), should I also "match" tags?
c
yes
https://docs.prefect.io/concepts/work-queues/#work-queue-concurrency
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For example, a work queue with a concurrency limit of 5 will only release new work if fewer than 5 matching runs are currently in a Running or Pending state. If 3 runs are Running or Pending, polling the queue for work will only result in 2 new runs, even if there are many more available, to ensure that the concurrency limit is not exceeded.
The matching runs are based on tags, not necessarily the queue itself
i
I don't understand, sorry
I have a queue concurrency limit of 1, one task have been running, second task still started (it was autoscheduled)
By task I mean flow here (couldn't set tags on flows as far as I see)
Here is a picture:
Liberal-grebe was started manually at 6:55 p, yesterday
It was running 17 hours before failing, so up until 12 am today. Teal-calm started at 5 am today, while another flow has been running
And as you see flow run concurrency is 1 on the picture
Previously flow run concurrency was working fine for me
May be the problem is because this run was manually triggered?
Sorry for so much text, really appreciate your time looking into this
c
When you click into the flow-run for each, what are the tags assigned - e.g.:
i
One has a tag "autoscheduled"
Another has no tags
c
That would be the discrepancy
The concurrency is matching tags
if the tags don’t match, concurrency is not enforced as it’s unaware that it needs to be enforced
i
Thanks!
But to be honest, it's a bit strange behaviour
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