What are the different LFU cache eviction strategies?

What are the different LFU cache eviction strategies?

LFU, or Least Frequently Used, cache eviction strategies prioritize removing the least accessed items. Common strategies include:

1. Basic LFU: Removes the item with the lowest access count.
2. LFU with a time decay: Reduces the access count over time to prevent stale data from being retained.
3. Adaptive LFU: Combines LFU with other strategies to adapt based on usage patterns.

Can you explain how the time decay works in LFU?

Time decay in LFU works by gradually reducing the access count of items over time. This means that even if an item was accessed frequently in the past, its relevance diminishes if it hasn't been accessed recently. This helps keep the cache updated with more current data.

What are the advantages of using LFU over other eviction strategies?

LFU is beneficial because it effectively retains frequently accessed items, which can lead to better cache hit rates. It also adapts well to stable access patterns, ensuring that popular items remain in the cache longer than less popular ones.

Are there any downsides to using LFU?

Yes, LFU can be more complex to implement and may require more memory to track access counts. Additionally, it can struggle with rapidly changing access patterns, potentially leading to suboptimal cache performance.