Fix/keep around finished forecasting jobs longer

[Flix6x]

Description

• Keep around finished forecasting jobs just as long as the FLEXMEASURES_PLANNING_TTL config setting for scheduling jobs
• Added changelog item in documentation/changelog.rst

Look & Feel

Finished forecasting jobs were disappearing after the default result_ttl of 500 seconds. They now remain in the finished job registry just as long as scheduling jobs.

How to test

Set the FLEXMEASURES_PLANNING_TTL to 10 seconds and run a forecasting job while checking rq-dashboard.

Related Items

• Probably helps Feat/add fetch forecasts endpoint #1823 as well, so the forecasting results won't feel like they expire after 500 seconds.

[read-the-docs-community]

Documentation build overview

📚 flexmeasures | 🛠️ Build #30700883 | 📁 Comparing fb0b840 against latest (08d77fa)

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changelog.html	📝 modified
api/v3_0.html	📝 modified

[BelhsanHmida]

Looking at the current call sites, both FLEXMEASURES_JOB_TTL and
FLEXMEASURES_PLANNING_TTL are immediately used with .total_seconds()
and default to timedelta(-1).

Based on this, the expected format is implicitly a datetime.timedelta.
Other formats (e.g. int or string values like "PT2D") are not supported
by the current implementation and will fail at runtime (e.g.
AttributeError: 'int' object has no attribute 'total_seconds').

So at the moment, the effective contract is that
FLEXMEASURES_*_TTL must be set as a timedelta in the config, which
doesn’t seem ideal from a user perspective.

It might be worth addressing this by accepting either an int (days)
or an ISO-8601 duration string, while keeping the current defaults.

[BelhsanHmida]

Looking at the current call sites, both FLEXMEASURES_JOB_TTL and FLEXMEASURES_PLANNING_TTL are immediately used with .total_seconds() and default to timedelta(-1).

Based on this, the expected format is implicitly a datetime.timedelta. Other formats (e.g. int or string values like "PT2D") are not supported by the current implementation and will fail at runtime (e.g. AttributeError: 'int' object has no attribute 'total_seconds').

So at the moment, the effective contract is that FLEXMEASURES_*_TTL must be set as a timedelta in the config, which doesn’t seem ideal from a user perspective.

It might be worth addressing this by accepting either an int (days) or an ISO-8601 duration string, while keeping the current defaults.

i made this pr as fix for this issue #1882