# Overriding queue for single task

**URL:** <https://cylc.discourse.group/t/overriding-queue-for-single-task/369>\
**Category:** Cylc Support\
**Created:** [August 19, 2021, 3:50pm UTC](https://cylc.discourse.group/t/overriding-queue-for-single-task/369 "2021-08-19T15:50:04Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![nhsavage](https://yyz2.discourse-cdn.com/free1/user_avatar/cylc.discourse.group/nhsavage/32/139_2.png) [@nhsavage](https://cylc.discourse.group/u/nhsavage)\
**Post date:** [August 19, 2021, 3:50pm UTC](https://cylc.discourse.group/t/overriding-queue-for-single-task/369/1 "2021-08-19T15:50:04Z")

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I have a large suite which uses internal queues to prevent overwhealming the scheduler. I am currently trying to fix a problem with one of the tasks via some manual intervention but manually triggering the tasks sends it to the back of the queue which is not ideal in this scenario - I need to know if my fix has worked.

Is there a way to force this one task to trigger immediately?

I thought I could perhaps use cylc trigger for this, but I can’t see what state to set the job to.

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**Author:** ![wxtim](https://yyz2.discourse-cdn.com/free1/user_avatar/cylc.discourse.group/wxtim/32/151_2.png) [@wxtim](https://cylc.discourse.group/u/wxtim)\
**Post date:** [August 20, 2021, 9:24am UTC](https://cylc.discourse.group/t/overriding-queue-for-single-task/369/2 "2021-08-20T09:24:47Z")

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Have you tried holding the workflow (suite) before triggering off the failed task? I think this does what you want if [my toy workflow](https://github.com/wxtim/workflows/tree/master/Queues) duplicates your problem correctly.

#### …CLI instructions…

```bash
cylc hold <my_workflow_name>
cylc trigger <my_workflow_name> <my_task_name>.<cycle_point>

```

> n.b.  
> `<my_task_name>.<cycle_point>` can be a glob, so you can trigger multiple tasks.

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<div class="post-metadata">

**Author:** ![hilary.j.oliver](https://yyz2.discourse-cdn.com/free1/user_avatar/cylc.discourse.group/hilary.j.oliver/32/4_2.png) [@hilary.j.oliver](https://cylc.discourse.group/u/hilary.j.oliver)\
**Post date:** [August 20, 2021, 12:13pm UTC](https://cylc.discourse.group/t/overriding-queue-for-single-task/369/3 "2021-08-20T12:13:35Z")

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@nhsavage - @wxtim’s suggestion might work too (haven’t tried) but it should work like this:

- if you trigger a waiting task, it will get queued
  - if the queue is not full, the task will be released to submit immediately, otherwise it is queued

- if you trigger a queued task, it will submit immediately regardless of queue limiting

i.e. using `cylc trigger` once says “queue this task now”; and using it again says “submit this queued task now”.

This is deliberate in case the queue limits are really important.

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<div class="post-metadata">

**Author:** ![hilary.j.oliver](https://yyz2.discourse-cdn.com/free1/user_avatar/cylc.discourse.group/hilary.j.oliver/32/4_2.png) [@hilary.j.oliver](https://cylc.discourse.group/u/hilary.j.oliver)\
**Post date:** [August 20, 2021, 12:17pm UTC](https://cylc.discourse.group/t/overriding-queue-for-single-task/369/4 "2021-08-20T12:17:36Z")

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Documented in `cylc trigger --help` (which of course you might not be aware of if doing it via the GUI):

> NOTE waiting tasks that are queue-limited will be queued if triggered, to  
> submit as normal when released by the queue; queued tasks will submit  
> immediately if triggered, even if that violates the queue limit (so you may  
> need to trigger a queue-limited task twice to get it to submit immediately).

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<div class="post-metadata">

**Author:** ![nhsavage](https://yyz2.discourse-cdn.com/free1/user_avatar/cylc.discourse.group/nhsavage/32/139_2.png) [@nhsavage](https://cylc.discourse.group/u/nhsavage)\
**Post date:** [August 20, 2021, 5:53pm UTC](https://cylc.discourse.group/t/overriding-queue-for-single-task/369/5 "2021-08-20T17:53:47Z")

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thank you - I think that the double triggering is the key thing I missed - I was using commands, but I hadn’t realised that triggering something in the queue made it trigger immediately. Holding the suite didn’t seem to help me (I had tried that) - it looked like the hold prevented my triggered tasks from running at all (although possibly double triggering would help with that too). All useful stuff thanks.

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<div class="post-metadata">

**Author:** ![nhsavage](https://yyz2.discourse-cdn.com/free1/user_avatar/cylc.discourse.group/nhsavage/32/139_2.png) [@nhsavage](https://cylc.discourse.group/u/nhsavage)\
**Post date:** [August 21, 2021, 6:09am UTC](https://cylc.discourse.group/t/overriding-queue-for-single-task/369/6 "2021-08-21T06:09:15Z")

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I have just tested this in a running suite. The first time I triggered it, the job didn’t change state and just had a last message “waiting for job host selection”. The second time it did submit ok. This suite is probably pushing the limits of cylc 7 as it has 36 members with 4 nests running at once and has 1 hour cruns (I should probably push that longer tbh).