Hands‑On Experience with Spring Boot 3.2, JDK 21, and GraalVM Native Images

Binary (native) deployment

Define a minimal Spring Boot application with @RestController and @GetMapping("/customers") that returns a Set.of of three Customer records. Build a GraalVM native image and launch it. Startup completes in sub‑second time. Load test using ab -c 50 -n 10000 reports:

Requests per second:    7076.39 [#/sec] (mean)
Time per request:       7.066 ms (mean)
Memory usage: ~70 MB (peak), ~20 MB idle

The binary cannot be monitored with JConsole or Arthas because it runs without a JVM.

Jar deployment

The same source is packaged as a regular JAR (size 19 MB). Load testing yields:

Requests per second:    557.72 [#/sec] (mean)
Time per request:       89.651 ms (mean)
Memory usage: ~200 MB (peak), ~160 MB idle

Performance improves after JVM warm‑up, confirming the need for pre‑warming.

Go comparison

An equivalent Go program using only the standard library serves /customers. The binary size stays around 10 MB (up to 20 MB with a framework). Load test results:

Requests per second:    7247.68 [#/sec] (mean)
Time per request:       6.899 ms (mean)
Memory usage: ~10 MB idle

Rust comparison

An Actix‑web Rust service is built. Idle memory consumption is about 3 MB and rises to roughly 6 MB under load. Load test results:

Requests per second:    9163.48 [#/sec] (mean)
Time per request:       5.456 ms (mean)
Memory usage: ~6 MB peak

Compilation time on the author’s machine is notably long (≈ 1 ½ minutes):

$ time cargo build
cargo build  213.00s user 23.08s system 258% cpu 1:31.39 total

Build cost

Generating the native image takes about 15 minutes on a 2017 MacBook Pro:

Finished generating 'demo' in 14m 33s.
[INFO] BUILD SUCCESS
[INFO] Total time:  15:45 min
[INFO] Finished at: 2023-12-01T17:00:21+08:00

Conclusion

AOT‑processed native images for Spring Boot eliminate slow JVM startup, pre‑warm requirements, and high memory consumption. The trade‑off is a very slow build process (≈ 15 minutes). This demonstrates significant progress of Java in cloud‑native environments.

References

[1] https://spring.io/blog/2023/09/09/all-together-now-spring-boot-3-2-graalvm-native-images-java-21-and-virtual

[2] https://start.spring.io/