@EnableCaching annotation in Spring Boot - Performance & Optimization

Performance: @EnableCaching annotation

MEDIUM IMPACT

This annotation affects server-side response time by enabling caching, which reduces repeated data processing and speeds up response delivery.

Improving repeated data retrieval performance in a Spring Boot application

Spring Boot

// Add @EnableCaching to @SpringBootApplication or @Configuration class

@Service
public class ItemService {
    @Cacheable("items")
    public List<Item> getItems() {
        return itemRepository.findAll();
    }
}

Caches the result on first call and serves cached data on subsequent calls, reducing DB hits.

📈 Performance GainReduces server processing time and database load; faster response for repeated requests

Improving repeated data retrieval performance in a Spring Boot application

Spring Boot

public List<Item> getItems() {
    // fetches from database every time
    return itemRepository.findAll();
}

Every request triggers a database call causing slower responses and higher server load.

📉 Performance CostBlocks response for each request; increases server CPU and DB load

Performance Comparison

Pattern	Server Processing	Database Calls	Memory Usage	Verdict
No caching	High on repeated calls	One per request	Low	[X] Bad
With @EnableCaching	Low after first call	Single call cached	Increased due to cache	[OK] Good

Rendering Pipeline

While @EnableCaching does not affect browser rendering directly, it improves server response time, which can reduce Largest Contentful Paint (LCP) by delivering data faster.

→Server Processing

→Network Transfer

⚠️ BottleneckServer Processing time when fetching data repeatedly

Optimization Tips

1Use @EnableCaching to reduce repeated server processing for the same data.

2Cache results to lower database load and speed up responses.

3Monitor memory usage as caching increases server memory consumption.

Performance Quiz - 3 Questions

What is the main performance benefit of using @EnableCaching in Spring Boot?

A Reduces server processing time by caching method results

B Improves browser rendering speed directly

C Decreases memory usage on the server

D Eliminates network latency completely

DevTools: Network

How to check: Open DevTools Network tab, observe response times for repeated API calls to cached endpoints.

What to look for: Faster response times on repeated requests indicate effective caching.

Practice

1. What is the main purpose of the @EnableCaching annotation in a Spring Boot application?

easy

A. To activate caching support so methods annotated with @Cacheable can cache results

B. To disable all caching mechanisms in the application

C. To configure database connections automatically

D. To enable security features for REST endpoints

Solution

1. Step 1: Understand @EnableCaching role

   This annotation activates Spring's caching support, allowing caching annotations to work.

2. Step 2: Connect with @Cacheable

   Methods annotated with @Cacheable store their results in cache only if caching is enabled.

3. Final Answer:

   To activate caching support so methods annotated with @Cacheable can cache results -> Option A

4. Quick Check:

   @EnableCaching enables caching [OK]

Hint: Remember: @EnableCaching turns caching ON [OK]

Common Mistakes:

• Thinking @EnableCaching disables caching
• Confusing it with database or security annotations
• Assuming it caches data by itself without @Cacheable

2. Which of the following is the correct way to enable caching in a Spring Boot application?

easy

A. @CacheEnable

B. @EnableCache

C. @EnableCaching

D. @CachingEnable

Solution

1. Step 1: Recall the exact annotation name

   The correct annotation to enable caching is @EnableCaching.

2. Step 2: Check other options for typos

   Options B, C, and D are incorrect because they are not valid Spring annotations.

3. Final Answer:

   @EnableCaching -> Option C

4. Quick Check:

   Correct annotation spelling is @EnableCaching [OK]

Hint: Look for exact spelling: EnableCaching, not EnableCache [OK]

Common Mistakes:

• Using incorrect annotation names with similar words
• Missing the capital 'C' in Caching
• Confusing with other Spring annotations

3. Given the following Spring Boot code snippet, what will be the output when getData() is called twice?

@EnableCaching
@Service
public class DataService {
  private int count = 0;

  @Cacheable("dataCache")
  public String getData() {
    count++;
    return "Call number: " + count;
  }
}

medium

A. ["Call number: 1", "Call number: 1"]

B. ["Call number: 2", "Call number: 2"]

C. ["Call number: 0", "Call number: 1"]

D. ["Call number: 1", "Call number: 2"]

Solution

1. Step 1: Understand caching effect on method calls

   The first call to getData() runs the method, increments count to 1, and caches the result.

2. Step 2: Analyze second call behavior

   The second call returns the cached result without running the method again, so count stays 1.

3. Final Answer:

   ["Call number: 1", "Call number: 1"] -> Option A

4. Quick Check:

   Cache returns same result on repeated calls [OK]

Hint: Cached method runs once; repeated calls return cached result [OK]

Common Mistakes:

• Assuming count increments on every call despite caching
• Ignoring that @Cacheable caches method output
• Confusing cache key usage

4. Identify the error in the following Spring Boot configuration that prevents caching from working:

@Configuration
public class CacheConfig {
  @Bean
  public CacheManager cacheManager() {
    return new ConcurrentMapCacheManager("items");
  }
}

medium

A. Cache name "items" is invalid

B. Missing @EnableCaching annotation on configuration class

C. CacheManager bean should return null

D. CacheManager must be annotated with @Service

Solution

1. Step 1: Check caching activation

   Defining a CacheManager bean is not enough; caching must be enabled with @EnableCaching.

2. Step 2: Verify other options

   CacheManager returning null or invalid cache names are incorrect; @Service is unrelated here.

3. Final Answer:

   Missing @EnableCaching annotation on configuration class -> Option B

4. Quick Check:

   Enable caching with @EnableCaching [OK]

Hint: Always add @EnableCaching to activate caching [OK]

Common Mistakes:

• Forgetting to add @EnableCaching annotation
• Misunderstanding CacheManager bean role
• Wrong annotation usage on CacheManager

5. You want to cache results of a method that takes a user ID and returns user details. You also want to clear the cache when user data updates. Which combination of annotations and configuration correctly achieves this in Spring Boot?

hard

A. Use @EnableCaching on service class, @CachePut("users") on get method, and no annotation on update method

B. Use @CacheEvict on config class, @EnableCaching on update method, and no caching on get method

C. Use @Cacheable("users") on config class, @EnableCaching on get method, and @CacheEvict on update method

D. Use @EnableCaching on config class, @Cacheable("users") on get method, and @CacheEvict(value = "users", key = "#userId") on update method

Solution

1. Step 1: Enable caching globally

   Add @EnableCaching on a configuration or main class to activate caching support.

2. Step 2: Cache method results and evict on update

   Use @Cacheable("users") on the method fetching user details to cache results. Use @CacheEvict(value = "users", key = "#userId") on the update method to clear cache for that user.

3. Final Answer:

   Use @EnableCaching on config class, @Cacheable("users") on get method, and @CacheEvict(value = "users", key = "#userId") on update method -> Option D

4. Quick Check:

   Enable caching + cache get + evict on update [OK]

Hint: Enable caching, cache gets, evict on updates [OK]

Common Mistakes:

• Not enabling caching globally with @EnableCaching
• Using @CachePut instead of @CacheEvict for clearing cache
• Placing annotations on wrong classes or methods