John Spray 24f8133e89 safekeeper: add eviction_min_resident to stop evictions thrashing (#8335) ...

## Problem

- The condition for eviction is not time-based: it is possible for a
timeline to be restored in response to a client, that client times out,
and then as soon as the timeline is restored it is immediately evicted
again.
- There is no delay on eviction at startup of the safekeeper, so when it
starts up and sees many idle timelines, it does many evictions which
will likely be immediately restored when someone uses the timeline.

## Summary of changes

- Add `eviction_min_resident` parameter, and use it in
`ready_for_eviction` to avoid evictions if the timeline has been
resident for less than this period.
- This also implicitly delays evictions at startup for
`eviction_min_resident`
- Set this to a very low number for the existing eviction test, which
expects immediate eviction.

The default period is 15 minutes. The general reasoning for that is that
in the worst case where we thrash ~10k timelines on one safekeeper,
downloading 16MB for each one, we should set a period that would not
overwhelm the node's bandwidth.

2024-07-10 19:38:14 +01:00

..

walproposer_sim

safekeeper: add eviction_min_resident to stop evictions thrashing (#8335)

2024-07-10 19:38:14 +01:00

misc_test.rs

Discrete event simulation for safekeepers (#5804)

2024-02-12 20:29:57 +00:00

random_test.rs

Panic on unexpected error in simtests (#8169)

2024-06-26 16:46:14 +01:00

simple_test.rs

Discrete event simulation for safekeepers (#5804)

2024-02-12 20:29:57 +00:00