Question about caching behaviour: I'm in the process of active development of a certain flow. Flow runs with K8s agent packaged in Docker. There's one task that takes a lot of time. Task is decorated with

result=GCSResult

and

cache_for=timedelta(hours=1)

. I notice, that when I'm not rebuilding docker image Prefect is respecting cache, i.e. second run goes much faster than first. But it seems that each rebuild of an image invalidates cache. Q: is it true? How can I get more insight on how caching works?

Hey @Andrey Tatarinov, If I’m not mistaken, the cache should be respected for your subsequent runs despite rebuilding the image for that result type. Did you specify a

cache_validator

at all? There are a variety of cache_validators available to check the validity of your result which may be of some interest to you, if the subsequent run had different parameters for example - the cache won’t be respected (and we can use

cache_validator= prefect.engine.cache_validators.all_parameters

rather than the default).

I did not specify cache validator, and I expected that

duration_only

would be used.

IIRC, a newly registered flow to Prefect Cloud creates its own history with that image/storage/configurations, which would also correspond to a new result cache for that registered flow version. So that first run after a fresh registration would initiate the cache for subsequent runs… of that version of your flow.

What should I check?

Hmm, perhaps trying a run with a LocalResult and cache is a good place to start - checking to see whether the cache is respected for the duration across all versions of your flow or if it resets based on a new version. If a new result is created, then the cache only corresponds with a flow’s Active version and its configurations, in which case the result cache is live only for its flow version’s specified duration.