Why Apple Replaced Java with Swift for a High‑Performance Password Service

Recently, Apple’s development team revealed in a new case study that they feel “Java’s memory management can no longer keep up with our increasing demand and efficiency goals.”

Therefore, they started looking for a more efficient programming language.

They chose Swift, and said they achieved 50% lower hardware utilization, 90% less memory, and 40% higher throughput.

This project is about password monitoring, allowing users to check their passwords against a leaked password list. The development team said the application “receives billions of requests from global devices every day.”

The service runs on Linux and uses layered encryption, which makes each request require more compute resources.

The core developers said: “We have used Java for years to support large‑scale, critical tasks because it is stable and performant.”

However, Java’s garbage collection has issues, so they decided to switch languages.

Garbage collection (GC) is an automatic memory management technique that periodically cleans up unused memory. Although Java’s GC has improved, under high load GC pauses and performance overhead remain problematic.

Also, Java is a bit difficult to scale.

Service load varies greatly within a day; Apple adjusts hardware architecture and bandwidth as needed. When new hardware must be started, startup time is critical, and hosted languages like Java, with high runtime requirements, start slower.

Finally, they decided to rewrite the service in Swift.

Swift, developed by Apple, is the new choice replacing Objective‑C. They use the open‑source web framework Vapor. Swift also has automatic memory management, but it uses ARC (automatic reference counting).

ARC compared to other GC methods is controversial; however, in their service the team observed significant improvements, such as a 90% reduction in memory usage on services running in Kubernetes and a 50% reduction in hardware utilization.

In terms of code porting, the number of code lines decreased by nearly 85%, which may be more important than memory improvements. The team found Swift has features that make code cleaner, such as emphasizing protocols over inheritance, using async and await for concurrency, and type safety that eliminates the need for null checks.

Is Swift more efficient than Java? Or is the rewrite just for cleaner code? Both may be true.

Swift compiles directly to native code, without needing the JVM or JIT.

Apple promotes Swift for its own reasons; although the team hinted that after abandoning Java, Swift is not the only option, internal pressure is high, and moving to Go (Kubernetes’ development language) or Rust could bring similar improvements.

Java is celebrating its 30th birthday; its efficiency and reliability are widely recognized. While the Java community may be disappointed, it is worth noting that migrating to a more efficient language can bring huge performance gains and cost savings.

Author: 场长