In today’s fast-paced digital landscape, high-performance web applications demand lightning-fast APIs. Bottlenecks in server-side logic can cripple the user experience, especially during high-traffic surges. Recently, our backend engineering team at Associative tackled a severe concurrency issue for a complex web application.

While we operate under strict Non-Disclosure Agreements (NDAs) and never share specific client projects or intellectual property, we are excited to share the technical methodology behind our recent success: how we reduced API latency by 40% using Spring Boot virtual threads.

The Challenge: Traditional Thread-per-Request Bottlenecks

Historically, Java applications (including those built on Spring Boot) have relied on a traditional “thread-per-request” model. In this model, every incoming API request is assigned a dedicated operating system (OS) thread.

When an API needs to perform an I/O-intensive task—such as querying a PostgreSQL database or making a call to a third-party service—that OS thread is blocked. It sits idle, waiting for the external resource to respond. Under heavy load, the server quickly exhausts its pool of available OS threads, leading to cascading delays, increased memory consumption, and severely degraded API response times.

The Solution: Implementing Spring Boot Virtual Threads

To solve this, we turned to Java’s Project Loom and the newly integrated Virtual Threads feature in Spring Boot 3.2+.

Virtual threads are lightweight threads managed by the Java Virtual Machine (JVM) rather than the operating system. When a virtual thread encounters a blocking I/O operation, the JVM seamlessly unmounts it from the underlying carrier OS thread. This frees up the OS thread to handle other incoming API requests immediately. Once the I/O operation completes, the virtual thread is remounted and resumes execution.

Our implementation process included:

  1. Upgrading the Stack: Ensuring the environment was running Java 21+ and Spring Boot 3.2+.

  2. Enabling Virtual Threads: Simply setting spring.threads.virtual.enabled=true in our configuration properties.

  3. Refactoring Concurrency: Auditing our existing ExecutorService implementations and transitioning them to use Executors.newVirtualThreadPerTaskExecutor().

  4. Database Connection Tuning: Adjusting our connection pooling (HikariCP) to handle the massive increase in concurrent database requests without overwhelming the database server.

The Results: A 40% Drop in Latency

The impact was immediate and measurable.

By decoupling our application’s concurrency limits from the operating system’s hardware threads, we achieved:

  • 40% Reduction in Average API Latency: I/O blocking no longer stalled the entire server, drastically lowering the time it took to resolve complex endpoints.

  • Higher Throughput: The application could handle significantly more concurrent users without needing additional server infrastructure or cloud resources.

  • Optimized Memory Footprint: Virtual threads consume a fraction of the memory compared to traditional OS threads, freeing up valuable RAM.

About Associative: Your Partner in Digital Innovation

This technical optimization is just one example of how we solve complex problems. Established on February 1, 2021, Associative is a software development firm headquartered in Pune, Maharashtra, India. We are a team of dedicated innovators, problem-solvers, and IT professionals passionate about transforming visionary ideas into scalable digital realities.

We are formally registered with the Registrar of Firms (ROF), Pune, and are proud to be an Adobe Silver Solution Partner and an Official Reseller Partner of Strapi.

Our Comprehensive Service Portfolio

We offer a one-stop-shop for businesses seeking to innovate across a vast spectrum of domains:

  • Cloud & CMS Solutions: Scalable server-side logic using Java (Spring Boot, Jakarta EE), Node.js, Python, PHP, and Ruby on Rails. Expertise in Headless CMS (Strapi, Contentful) and modern front-end frameworks (React, Angular, Next.js).

  • Mobile Application Development: Native (Android, iOS) and cross-platform (Flutter, React Native) development.

  • AI & Machine Learning: Core AI, Generative AI (LLMs using LangChain, Ollama), and Computer Vision.

  • Blockchain & Web3: Smart contracts, DeFi, and NFT marketplace development.

  • Game Development, AR & VR: Immersive worlds using Unreal Engine 5, Unity, and AR/VR technologies.

  • Specialized Enterprise Solutions: High-frequency trading platforms, CRM/ERP customization, and end-to-end IoT solutions.

  • Digital Marketing: SEO, PPC, and marketing automation.

  • Innovation & R&D (NexusReal): Our flagship platform bridging digital intelligence and physical reality with AI Avatars and realistic human cloning.

Unyielding Transparency & Client Confidentiality

We operate strictly on a time-and-materials basis with transparent billing (daily, weekly, or milestone-based). Confidentiality is foundational to us:

  • Strict NDAs: We do not maintain a public portfolio to protect your IP.

  • 100% Ownership: Upon final payment, you receive full ownership of the source code.

  • Secure Environment: Our developers work exclusively from our secure offices.

Ready to Optimize Your Infrastructure?

If your applications are suffering from high latency or you are looking to build scalable, future-proof software, let’s connect.

  • Address: Khandve Complex, Yojana Nagar, Lohegaon – Wagholi Road, Lohegaon, Pune, Maharashtra, India – 411047

  • WhatsApp: +91 9028850524

  • Email: info@associative.in

  • Website: https://associative.in

  • Office Hours: 10:00 AM to 8:00 PM (Monday through Saturday)

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Case Study: How We Reduced API Latency by 40% Using Spring Boot Virtual Threads