turboFei commented on PR #7220:
URL: https://github.com/apache/kyuubi/pull/7220#issuecomment-3359323799
In **Guava’s `Cache` API**, the method `cache.cleanUp()` is used to
**synchronously perform maintenance operations** on the cache.
Here’s what it does in detail:
---
### 🔹 Purpose of `cleanUp()`
* Guava caches perform most maintenance operations (like evicting expired
entries or removing entries exceeding maximum size) **lazily** — that is,
during normal cache operations such as `get`, `put`, or `getIfPresent`.
* The `cleanUp()` method forces the cache to immediately run these pending
maintenance tasks.
---
### 🔹 When to Use It
* Normally, you **don’t need to call** `cleanUp()` yourself; Guava handles
it during cache operations.
* But in some cases — like when you want to:
* **Benchmark** cache performance without pending work affecting results.
* **Manually trigger eviction** (e.g., after setting `expireAfterWrite` or
`maximumSize`).
* **Ensure consistency** before shutting down an application or running a
test — you might explicitly call `cleanUp()`.
---
### 🔹 Important Notes
* `cleanUp()` does **not** block future writes or reads. It just runs
pending maintenance at the time of the call.
* If your cache uses expiration or size-based eviction, `cleanUp()` ensures
those rules are applied **immediately**, rather than waiting for the next
normal operation.
* It’s typically lightweight but should not be called in a tight loop —
Guava already optimizes cleanup frequency internally.
---
✅ **In short**:
`cache.cleanUp()` forces the cache to process pending evictions (expired
entries, over-capacity entries, etc.) right away instead of waiting for normal
access patterns to trigger cleanup.
---
Would you like me to also show you a **small code example** demonstrating
how entries are only removed after `cleanUp()` is called?
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