Flushing the cache in Pennant can affect system performance, primarily because cache flushing forces the system to discard stored data that speeds up repeated operations, leading to slower response times until the cache is rebuilt.
Details on Pennant Cache and Flushing:
- Laravel Pennant uses an in-memory cache to store resolved feature flags for the duration of a single request. This caching prevents repeated database queries for the same feature flag within that request, improving performance[2].
- When you manually flush the Pennant cache using the `Feature::flushCache()` method, you clear this in-memory cache. This means subsequent feature checks will have to query the database again, which can increase database load and slow down request handling temporarily until the cache is rebuilt[2][7].
General Impact of Cache Flushing on Performance:
- Flushing cache causes all transactions or operations that rely on cached data to fetch fresh data from the database or underlying storage, which is slower than accessing cached data. This leads to increased latency and higher resource consumption until the cache is repopulated[1][9].
- In broader system contexts (e.g., ServiceNow or database systems), cache flushes triggered by upgrades, plugin installations, or manual scripts can cause noticeable slowdowns and increased response times, sometimes resulting in errors due to resource contention[1][9].
- Similarly, in database systems, clearing procedure caches (akin to flushing) causes query plans to be regenerated, which spikes CPU usage and removes historical query performance data, complicating troubleshooting and temporarily degrading performance[10].
Summary:
Flushing the cache in Pennant will temporarily degrade system performance because it removes cached feature flag results, forcing repeated database queries until the cache is rebuilt. This can increase database load and slow down request processing. Therefore, cache flushes should be done judiciously, ideally outside of peak usage periods, to minimize impact on system responsiveness[1][2][7][9].
No direct evidence suggests that flushing Pennant's cache causes permanent performance damage, but the temporary slowdown and increased database load are important considerations when deciding to flush the cache.
Citations:
[1] https://support.servicenow.com/kb?id=kb_article_view&sysparm_article=KB0822644
[2] https://laravel.com/docs/11.x/pennant
[3] https://laracasts.com/episodes/2685
[4] https://stackoverflow.com/questions/77078816/how-to-disable-caching-for-laravel-pennant-in-db
[5] https://arxiv.org/pdf/2204.05508.pdf
[6] https://docs.netapp.com/us-en/e-series-santricity/sm-settings/what-is-cache-flushing.html
[7] https://github.com/laravel/pennant/issues/68
[8] https://www.reddit.com/r/brave_browser/comments/1e1qfeh/does_clearing_browser_cachehistory_really_improve/
[9] https://support.servicenow.com/kb?id=kb_article_view&sysparm_article=KB0793295
[10] https://www.sqlskills.com/blogs/erin/sqlskills-101-the-other-bad-thing-about-clearing-procedure-cache/