Recently, I attended the Code on JVM Chennai meetup, and it was an incredible learning experience. As someone transitioning into software development and currently learning Full Stack Java, events like these help bridge the gap between classroom learning and real-world software engineering.

The meetup featured three insightful sessions, each offering a unique perspective on modern software development.

Session 1: DSA in Production

Speaker: Hareesh Rajendran (Founder & CEO, Hayan Tech)

This session completely changed the way I think about Data Structures and Algorithms (DSA).

As beginners, we often associate DSA with coding interviews and competitive programming. But this session demonstrated how many advanced data structures quietly power the applications we use every day.

1. Bloom Filter

A Bloom Filter is a memory-efficient probabilistic data structure used to quickly determine whether an element might exist in a dataset.

Instead of storing every value, it stores compact information, making lookups extremely fast while consuming very little RAM.

Some real-world applications include:

• Instagram username availability checks


• Apache Cassandra


• Google Chrome


• Feed readers

2. HNSW Graph (Hierarchical Navigable Small World)

One of the most important data structures behind modern AI applications.

It enables extremely fast similarity searches across millions of vectors, making AI-powered search practical.

Common applications include:

• Vector Databases


• AI Search


• Recommendation Systems


• Retrieval-Augmented Generation (RAG)

One interesting takeaway was seeing how AI products rely on efficient data structures—not just machine learning models.

3. Skip List

A Skip List is an alternative to balanced trees that allows fast searching, insertion, and deletion.

Real-world usage:

• Redis Sorted Sets


• Rate Limiting


• RocksDB Storage Engine

4. LSM Tree (Log-Structured Merge Tree)

An LSM Tree is designed for systems that perform a huge number of write operations.

It is widely used in databases and storage systems because it optimizes write performance.

Applications include:

• Storage Engines


• Databases


• Live Streaming Systems

5. Consistent Hashing

Consistent Hashing distributes requests across multiple servers while minimizing data movement whenever servers are added or removed.

It is heavily used in distributed systems such as:

• Akamai CDN


• Netflix


• Amazon DynamoDB


• Discord Routing

The speaker also recommended exploring the Netflix Engineering Blog to understand how these concepts are used in production.

6. Hexagonal Grid (H3)

A geospatial indexing system that divides maps into hexagonal cells for efficient location-based processing.

Applications include:

• Ola


• Uber


• Swiggy


• Zomato

The recommendation to read the H3 Engineering Blogs was another valuable takeaway.

7. HyperLogLog

HyperLogLog is a probabilistic algorithm used to estimate the number of unique elements while using very little memory.

Instead of counting every item exactly, it provides an approximate count with impressive accuracy.

Examples include:

• Reddit


• Analytics Dashboards


• Google BigQuery

My Biggest Takeaway

This session completely changed my perspective on DSA.

It's not just about solving interview problems—it's about building systems capable of serving millions of users efficiently.

Session 2: Uncovering Ideas Worth Building in the AI Era

Speaker: Agnel John (Founder & CEO, Error Makes Clever)

This session shifted the focus from technology to entrepreneurship.

One of the strongest messages was that building a product alone is never enough. The real challenge is creating something that solves a genuine problem and that people are willing to pay for.

Some important takeaways were:

• Build your idea instead of waiting for the "perfect time."


• Learn how your product can generate revenue.


• A product by itself is never your competitive advantage—execution, customer understanding, and continuous improvement matter much more.


• Before building something big, find someone within your own circle who is willing to pay for your solution.


• Once you've validated your idea, commit fully and keep improving it.


• Getting your first paying customer is a significant milestone because it proves that you're solving a real problem.

As someone still learning development, this session reminded me that writing code is only one part of building successful software. Understanding users and solving meaningful problems are equally important.

Session 3: Streaming Large File Downloads in Java

Speaker: Kalaivani Mohan (Software Engineer, IBM)

The final session focused on an important backend engineering concept—streaming large file downloads.

A common mistake is trying to load an entire large file into memory before sending it to the user. This can consume excessive RAM and affect application performance.

Instead, Java applications use streaming, where files are sent in smaller chunks.

This approach offers several benefits:

• Lower memory consumption


• Better application performance


• Faster response times


• Improved scalability

Streaming is commonly used while serving:

• Videos


• PDF documents


• Reports


• Cloud storage downloads


• Enterprise applications

Although the concept sounds simple, it's an excellent example of how small implementation decisions can make applications significantly more efficient.

Final Thoughts

Each session taught me something different.

The first session showed how advanced data structures power large-scale systems used by millions of users.

The second session reminded me that successful products are built around real customer problems—not just great technology.

The third session demonstrated how backend engineering techniques improve performance and scalability.

As someone currently learning Full Stack Development, attending this meetup broadened my understanding of software engineering beyond coding tutorials and classroom lessons.

A heartfelt thank you to the organizers, speakers, and everyone involved in making Code on JVM Chennai such an informative and inspiring event.

I'm looking forward to attending more tech meetups, learning from experienced professionals, and continuing my journey as a software developer.

Every meetup is another step forward in the learning journey.