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Caching is the secret sauce for building fast, modern applications. It supercharges performance by tucking away frequently used data in a super-speedy memory layer. For Java apps, especially those built with microservices (the small, independent services approach), a simple local cache just doesn't cut it.
That's where “distributed caching” becomes a game-changer. It spreads your cached data across a network of servers, making your application more scalable, tougher against failures, and ensuring everyone sees the same data, regardless of which server handles their request.
This blog walks you through the best strategies, top technologies, and smart practices for using a distributed cache in your Java environment.
In a basic application, a local cache (think Guava or Caffeine) works fine. It lives right inside your application's memory and is lightning fast. But the moment you run multiple copies of your app (scaling horizontally), you hit a snag: keeping all those caches in sync.
Imagine this: A user updates their profile on “App Server 1.” That change is saved in that server's local cache. But if their next request goes to “App Server 2,” that server is still holding onto the old, outdated data. Yikes!
A distributed cache solves this mess. It creates one central, shared cache layer that all your application instances talk to. This way, everyone is on the same page, all the time.
The benefits are huge:
How your app talks to the cache and the database depends on the strategy you choose. It all comes down to your needs for speed and consistency.
This is a straightforward approach. Your application handles all the interactions with both the cache and the database.
Use this when: You read data more often than you write it, and you can tolerate a tiny delay while consistency catches up (eventual consistency).
Here, the cache acts as a go-between. The application only talks to the cache, making the underlying logic simple.
How it works: All read requests go to the cache. If the data isn't there, the cache itself automatically goes to the database to fetch it.
This ensures rock-solid consistency by writing to the cache and the database at the exact same time.
How it works: The app writes to the cache, which then synchronously writes to the database before confirming the operation is done.
This strategy prioritises super-fast writes by saving the database update for later.
How it works: The app writes to the cache for an immediate confirmation, and the cache quietly saves the data to the database in the background.
Use this when: You have tons of write operations and need low latency (speed is key).
The Java world has plenty of options. Here are a few popular choices:
| Technology | Pros | Cons | Use Case |
| Redis | Super-fast, lots of data types, great Spring integration. | Self-hosting can be a chore to manage. | General caching, user session management. |
| Hazelcast | Easy setup, finds other nodes automatically, flexible structure. | Can be complex to configure deeply. | Cloud-native apps need a robust, self-managed cache. |
| Apache Ignite | Full data grid features, SQL support, and high performance. | Steeper learning curve than Redis or Hazelcast. | Data-intensive apps need distributed SQL queries. |
Spring makes adding caching a breeze. You literally only need to:
Distributed caching is vital for building scalable and reliable Java applications today. By understanding the strategies (like Cache-Aside or Write-Behind) and choosing the right technology (Redis, Hazelcast, etc.), you can make informed decisions. Plus, frameworks like Spring Boot simplify the whole process, letting you focus on building lightning-fast applications.
Whether you're optimising Java application performance, implementing distributed caching architectures, or scaling microservices for enterprise workloads, our technical experts can guide your strategy. Ready to boost your applications? Drop us a line at reachus@covalensedigital.com or complete a quick contact form to start the conversation. Our team will connect with you shortly to discuss your performance goals!
Author
Pradeep Joshi, Principal Architect
An accomplished leader with over 20 years of experience, Pradeep excels in full life cycle development and enterprise architecture, with a focus on cloud-based solutions. He specialises in Java, Spring Boot, microservices, and AWS, using these technologies to design scalable systems and deliver innovative solutions. Pradeep frequently shares his expertise through blogs and whitepapers on emerging IT trends.