What are common cache eviction policies? (e.g., LRU, LFU, FIFO)
What are common cache eviction policies?
571
02-Apr-2025
Updated on 14-Apr-2025
Khushi Singh
14-Apr-2025Caches make use of eviction policies to determine which cached data needs removal as the storage approaches full capacity or when the information becomes obsolete. These policies function to identify which cached data needs elimination so new information can be added to the cache space. The most prevalent cache eviction policies include the following examples:
Least Recently Used (LRU):
LRU follows a mechanism to discard cache entries that remain unused for the longest periods of time. A LRU policy assumes that data that remains unused recently will probably remain unused in the near future.
The Ideal Use Case for this policy relates to situations that demand recent data reusability.
First In, First Out (FIFO)
Under FIFO the system eliminates the cache entry which entered the cache system first. LRU operates by selecting for deletion the oldest data stored in the cache before loading new data.
Simple implementation exists although it might not provide the most efficient solution because frequency and recency of access remain unconsidered.
Least Frequently Used (LFU)
LFU removes from the cache the entry that people access fewest times. When space becomes available the cache entry system selects the entry with the lowest counter value to remove since this indicates minimum number of accesses.
The Suitable use case for this method occurs when you need to allocate data priority according to usage frequency instead of recent access patterns.
Random Replacement
The eviction process happens by selecting a random cache entry during new caching requirements. Other policies prove difficult to implement which makes this method an effective choice since it operates independently of usage trends.
Applications using the Use case frequently select it because simplicity matters while caching patterns remain unpredictable.
Time-to-Live (TTL)
The cache entry process contains life timelines for each object which leads to automatic deletion when the designated time ends. Engineers employ this strategy for data that becomes outdated after set periods in specific applications.
This strategy enables web caching of both API responses and web pages by setting expiration deadlines.
Most Recently Used (MRU)
The primary function of MRU involves removing the entry that was accessed most recently. The policy applies that data which gets accessed currently is unlikely to be needed for future short-term use.
Use case can apply to particular situations when more recent data has lower chances of reuse.
System implementation team selects cache eviction policies based on their different strengths because they match the specific use cases and system requirements including data access patterns and application types.