Rust Is Cool. But Java Just Did Something Smarter

For years, Rust has been the darling of the developer world. Fast. Safe. Modern. Every performance benchmark, every systems programming blog, every Hacker News thread — Rust was the language that made Java look like an ancient relic of enterprise boredom. But while everyone was busy arguing about ownership semantics and rewriting everything from kernels to web servers in Rust, Java quietly solved one of software’s oldest problems — and almost no one outside the JVM world noticed. That change has a name: Project Loom. And it might be the most important thing to happen to Java since the JVM itself.

The Boring Problem Nobody Talks About Every backend engineer knows this pain: you build a high-traffic service, spin up a few hundred threads, and suddenly your CPU starts screaming. Threads are expensive — not in concept, but in memory. Each traditional Java thread consumes about 1 MB of stack space, even if it’s just waiting on I/O. Multiply that by tens of thousands of concurrent requests, and you hit the wall. The standard workaround? You start juggling.

Use async I/O.
Embrace CompletableFutures.
Or move to reactive frameworks like Vert.x or Spring WebFlux.

And then you end up with callback hell disguised as “reactive streams.” Readable code turns into spaghetti promises chained across abstractions that even seasoned developers pretend to understand. That’s where Project Loom quietly walked in — not with hype, not with a rebrand, but with a single question: “What if we could make threads cheap enough that you don’t need async hacks at all?”

Virtual Threads: The Uncool Miracle Loom’s virtual threads are lightweight threads managed by the JVM, not the operating system. They cost kilobytes, not megabytes. You can spawn millions of them without your machine breaking a sweat. Here’s the magic trick: when a virtual thread blocks on I/O (say, a database call), it’s not wasting a real OS thread. The JVM simply parks it, freeing the underlying resources. When the data comes back, it wakes it up again — seamlessly. No async boilerplate. No complex frameworks. Just plain, synchronous-looking code that performs like asynchronous code. // Old way: Futures and pain CompletableFuture<String> result = CompletableFuture.supplyAsync(() -> {

   return httpCall();

}).thenApply(response -> process(response));

// Loom way: Simpler, faster var thread = Thread.startVirtualThread(() -> {

   var response = httpCall();
   process(response);

}); The second example looks like 2005 Java — except it scales like 2030. Under the hood, the JVM turns this into a continuation — a suspended, resumable computation. No magic keywords. No new syntax. Just threads, but smarter.

Go Did It First — Java Did It Better If you’re thinking, “Wait, isn’t this just like Go’s goroutines?”, you’re absolutely right. The difference is philosophical. Go designed its concurrency model from scratch. It was elegant but rigid — channels, goroutines, and a scheduler built into the runtime. Java took a harder route: it retrofitted an entirely new concurrency model onto a 25-year-old runtime, without breaking compatibility. That’s like teaching a dinosaur to dance — and not just any dance, but a perfectly synchronized one. Go made concurrency easy. Loom made it invisible.

The Real Magic: Compatibility When new technologies promise performance, there’s always a catch. Usually, it sounds like: “You just need to rewrite your app.” Not here. Virtual threads work with your existing Java code, frameworks, and libraries. Spring Boot? Works. JDBC? Works. Blocking I/O? Works beautifully. You don’t need async drivers or reactive libraries to scale anymore. You just start your server with virtual threads and watch your throughput skyrocket — all while writing clean, synchronous code that your junior developer can actually debug. That’s the true genius of Loom. It didn’t force developers to think differently — it just made their old code faster.

The Debugging Paradox Every engineer who’s worked on a distributed system knows this: debugging async code is a nightmare. You set breakpoints, but the stack trace looks like a Picasso painting. You log everything, but context hops across threads and executors. With Loom, debugging feels like 2009 again — in a good way. Each virtual thread has a clean, predictable stack trace. When it blocks, it just… pauses. You can inspect it in your IDE like any normal thread. And because it’s integrated at the JVM level, your profiling tools, thread dumps, and observability pipelines just work. No more “what thread am I even in?” moments.

The Startup Revelation At a fintech startup I recently spoke with, engineers had spent months migrating to reactive programming to handle bursty traffic patterns. They switched to Loom in a staging environment — with zero code rewrite — and saw CPU usage drop by 40% and request latency improve by 25%. Their postmortem was almost funny: “We spent a year learning reactive programming. Loom made it obsolete in a week.”

Rust, We Still Love You This isn’t a Java-vs-Rust war. Rust is brilliant — it’s memory-safe, fearless, and built for systems where every nanosecond matters. But Rust is also unforgiving. You earn every line of code you write. And sometimes, you just need a runtime that carries some of that weight for you. Java’s strength has always been its balance — between abstraction and control, safety and speed, innovation and stability. Project Loom doesn’t make Java “modern.” It reminds us why Java still matters.

The Quiet Comeback If you look closely, something interesting is happening in the developer world. While the front page of Hacker News is filled with Rust, Zig, and Bun, quietly — almost secretly — large-scale backend systems are finding new life in Java again. Not because of hype. Because of momentum. Loom, combined with GraalVM and the new ZGC, turns Java from a heavyweight enterprise relic into a high-performance, polyglot, cloud-native powerhouse. It’s no longer “old reliable.” It’s new dangerous.

Final Thought: Maybe Boring Is the New Cool Every few years, a new language shows up to “replace” Java. But the thing about Java is — it never tries to win the hype war. It just quietly evolves until one day, it’s doing what the cool kids do… but at scale. Project Loom is a perfect example of that. It doesn’t try to look sexy. It just works — beautifully, predictably, efficiently. So maybe the lesson isn’t that Rust lost. It’s that Java stopped competing and started innovating again.