Concurrency events track when slots are acquired and released for named
concurrency limits. For more on concurrency limits, see
Global concurrency limits.
prefect.concurrency-limit.acquired
Emitted when concurrency slots are acquired for a named limit.
Resource
| Label | Description |
|---|
prefect.resource.id | prefect.concurrency-limit.{uuid} |
prefect.resource.name | Concurrency limit name |
slots-acquired | Number of slots acquired in this request |
limit | Maximum number of slots for this limit |
| Resource ID pattern | Role | When present |
|---|
prefect.concurrency-limit.{uuid} | concurrency-limit | One entry per other limit in the same acquisition batch (when acquiring multiple limits at once) |
Payload
This event has no payload.
prefect.concurrency-limit.released
Emitted when concurrency slots are released for a named limit. Uses the follows
field to link back to the corresponding acquired event.
Resource
Same as prefect.concurrency-limit.acquired.
Same as prefect.concurrency-limit.acquired.
Payload
This event has no payload.
Legacy v1 concurrency events
These events are emitted by the legacy tag-based concurrency limit system. For
new concurrency limits, use global concurrency limits which emit the events
documented above.
prefect.concurrency-limit.v1.acquired
Emitted when a legacy tag-based concurrency slot is acquired.
Resource
| Label | Description |
|---|
prefect.resource.id | prefect.concurrency-limit.v1.{uuid} |
prefect.resource.name | Tag name |
limit | Maximum number of slots |
task_run_id | ID of the task run acquiring the slot |
| Resource ID pattern | Role | When present |
|---|
prefect.concurrency-limit.v1.{uuid} | concurrency-limit | One entry per other limit in the same acquisition batch |
Payload
This event has no payload.
prefect.concurrency-limit.v1.released
Emitted when a legacy tag-based concurrency slot is released.
Resource
Same as prefect.concurrency-limit.v1.acquired.
Same as prefect.concurrency-limit.v1.acquired.
Payload
This event has no payload. 
