Quarkus で FizzBuzz する CLI を作ってみた / FizzBuzz with Quarkus

1. 2026/03/05 シネマ de LT会#2 〜Back to the Screen〜 Quarkus で FizzBuzz する CLI を 作ってみた #CinemaDeLT
2. Name: こたつ&&みかん Account: @kota2and3kan Company: Name: Scalar, Inc. Product: - ScalarDB (Distributed Transaction Manager) - ScalarDL (Byzantine Fault Detection Middleware) Job: [Technical Support, Infra Engineer] Like: DB: [PostgreSQL, CockroachDB] Bouldering: 5Q Dislike: Real Cockroach Who am I.
3. 今回作ったもの https://github.com/kota2and3kan/fizzbuzz-with-quarkus
4. FizzBuzz とは
5. 1 から順に数字を出力するプログラム。 ただし、 • 3の倍数の時は Fizz • 5の倍数の時は Buzz • 15の倍数の時は FizzBuzz と出力する。 FizzBuzz とは...
6. 1 2 Fizz 4 Buzz Fizz 7 8 Fizz Buzz FizzBuzz とは... (例) Fizz 22 23 Fizz Buzz 26 Fizz 28 29 FizzBuzz 11 Fizz 13 14 FizzBuzz 16 17 Fizz 19 Buzz
7. Quarkus とは
8. SUPERSONIC (超音速) で SUBATOMIC (亜原子) な Java https://quarkus.io/ Quarkus とは... (公式 HP 曰く)
9. なんかすごそう
10. ※補足※ Quarkus は Java の Distro ではなく、 Framework 的なもの。 Spring Framework とかと同じ立ち位 置のイメージ。
11. 触ってみました
12. 「すごい！」 と思った機能を 2つ紹介します
13. Native Image
14. GraalVM や Mandrel を使って Native Image (実行可能ファイル) を Build で きる
15. Native Image を build するコマンド $ quarkus build --native
 $ ./mvnw install -Dnative
 $ ./gradlew build -Dquarkus.native.enabled=true 
 quarkus コマンドを使う場合 ./mvnw コマンドを使う場合 ./gradlew コマンドを使う場合
16. $ quarkus build --native
 jdk-25: Pulling from quarkus/ubi9-quarkus-mandrel-builder-image
 Digest: sha256:f78109a604797780ae1b80fee6860e3017a77da1a1cb0152d601f48e3b1e69d2
 Status: Image is up to date for quay.io/quarkus/ubi9-quarkus-mandrel-builder-image:jdk-25
 quay.io/quarkus/ubi9-quarkus-mandrel-builder-image:jdk-25
 Warning: Option 'DynamicProxyConfigurationResources' is deprecated and might be removed in a future release: This can be caused by a proxy-config.json file in your META-INF directory. Consider including proxy configuration in the reflection section of reachability-metadata.md instead.. Please refer to the GraalVM release notes.
 ========================================================================================================================
 GraalVM Native Image: Generating 'fizzbuzz' (executable)...
 ========================================================================================================================
 For detailed information and explanations on the build output, visit:
 https://github.com/oracle/graal/blob/master/docs/reference-manual/native-image/BuildOutput.md
 ------------------------------------------------------------------------------------------------------------------------
 [1/8] Initializing... (6.0s @ 0.13GB)
 Java version: 25.0.2+10-LTS, vendor version: Mandrel-25.0.2.0-Final
 Graal compiler: optimization level: 2, target machine: x86-64-v3
 C compiler: gcc (redhat, x86_64, 11.5.0)
 Garbage collector: Serial GC (max heap size: 80% of RAM)
 5 user-specific feature(s):
 - com.oracle.svm.thirdparty.gson.GsonFeature
 - io.quarkus.runner.Feature: Auto-generated class by Quarkus from the existing extensions
 - io.quarkus.runtime.graal.DisableLoggingFeature: Adapts logging during the analysis phase
 - io.quarkus.runtime.graal.JVMChecksFeature
 - io.quarkus.runtime.graal.SkipConsoleServiceProvidersFeature: Skip unsupported console service providers when quarkus.native.auto-service-loader-registration is false
 ------------------------------------------------------------------------------------------------------------------------
 5 experimental option(s) unlocked:
 - '-H:+AllowFoldMethods' (origin(s): command line)
 - '-H:BuildOutputJSONFile' (origin(s): command line)
 - '-H:-UseServiceLoaderFeature' (origin(s): command line)
 - '-H:+GenerateBuildArtifactsFile' (origin(s): command line)
 - '-H:AddOpens' (alternative API option(s): --add-opens java.base/java.lang=ALL-UNNAMED; origin(s): command line)
 ------------------------------------------------------------------------------------------------------------------------
 Build resources:
 - 28.45GB of memory (56.3% of system memory, in container)
 - 14 thread(s) (100.0% of 14 available processor(s), determined at start)
 [2/8] Performing analysis... [*****] (34.4s @ 0.80GB)
 7,800 types, 9,916 fields, and 37,796 methods found reachable
 2,570 types, 78 fields, and 2,925 methods registered for reflection
 62 types, 68 fields, and 55 methods registered for JNI access
 0 downcalls and 0 upcalls registered for foreign access
 4 native libraries: dl, pthread, rt, z
 [3/8] Building universe... (3.6s @ 0.92GB)
 [4/8] Parsing methods... [**] (2.9s @ 0.98GB)
 [5/8] Inlining methods... [***] (2.3s @ 1.09GB)
 [6/8] Compiling methods... [*****] (32.0s @ 1.41GB)
 [7/8] Laying out methods... [**] (3.9s @ 1.66GB)
 [8/8] Creating image... [**] (4.7s @ 0.80GB)
 17.37MB (43.93%) for code area: 24,822 compilation units
 19.46MB (49.23%) for image heap: 230,591 objects and 60 resources
 2.70MB ( 6.84%) for other data
 39.54MB in total image size, 37.21MB in total file size
 ------------------------------------------------------------------------------------------------------------------------
 Top 10 origins of code area: Top 10 object types in image heap:
 12.07MB java.base 4.72MB byte[] for code metadata
 1.66MB svm.jar (Native Image) 2.80MB byte[] for java.lang.String
 870.63kB info.picocli.picocli-4.7.7.jar 1.99MB java.lang.String
 324.69kB fizzbuzz.jar 1.56MB com.oracle.svm.core.hub.DynamicHubCompanion
 322.20kB io.smallrye.config.smallrye-config-core-3.15.1.jar 1.11MB byte[] for general heap data
 307.13kB o.j.logmanager.jboss-logmanager-3.2.1.Final.jar 1.08MB java.lang.Class
 227.89kB jdk.zipfs 505.68kB java.util.HashMap$Node
 167.60kB io.quarkus.arc.arc-3.31.4.jar 458.28kB java.lang.Object[]
 163.81kB io.quarkus.quarkus-core-3.31.4.jar 369.31kB java.util.concurrent.ConcurrentHashMap$Node
 145.62kB jdk.proxy4 334.34kB java.lang.String[]
 735.03kB for 32 more packages 4.54MB for 2234 more object types
 ------------------------------------------------------------------------------------------------------------------------
 Recommendations:
 FUTR: Use '--future-defaults=all' to prepare for future releases.
 HEAP: Set max heap for improved and more predictable memory usage.
 CPU: Enable more CPU features with '-march=native' for improved performance.
 ------------------------------------------------------------------------------------------------------------------------
 6.9s (7.4% of total time) in 610 GCs | Peak RSS: 2.55GB | CPU load: 10.92
 ------------------------------------------------------------------------------------------------------------------------
 Build artifacts:
 /project/build-artifacts.json (build_info)
 /project/fizzbuzz (executable)
 /project/fizzbuzz-build-output-stats.json (build_info)
 ========================================================================================================================
 Finished generating 'fizzbuzz' in 1m 32s.
 
 BUILD SUCCESSFUL in 1m 50s
 13 actionable tasks: 13 executed
 Consider enabling configuration cache to speed up this build: https://docs.gradle.org/9.3.1/userguide/configuration_cache_enabling.html
 映画館の巨大スクリーンなら文字が小さくても (ry
17. Build された Native Image $ file ./build/fizzbuzz
 ./build/fizzbuzz: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, BuildID[sha1]=1572e96d1a6169e9629ea0609ec1d24c98e46b0c, for GNU/Linux 3.2.0, stripped
 
 $ ldd ./build/fizzbuzz
 linux-vdso.so.1 (0x00007ffc3b7f9000) 
 libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007eaf530d6000) 
 libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007eaf52e00000) 
 /lib64/ld-linux-x86-64.so.2 (0x00007eaf530fa000) 

18. Native Image なのでそのまま実行できる $ ./build/fizzbuzz --start 1 --end 15
 1
 2
 Buzz
 4
 Fizz
 Buzz
 7
 8
 Buzz
 Fizz
 11
 Buzz
 13
 14
 BuzzFizz

19. ちなみに
20. 普通に .jar も build できる $ ./gradlew build \
 -Dquarkus.native.enabled=false \ 
 -Dquarkus.package.jar.enabled=true \ 
 -Dquarkus.package.jar.type=uber-jar 
 $ ls -l ./build/fizzbuzz.jar 
 -rw-r--r-- 1 ubuntu ubuntu 5235424 Mar 1 14:40 ./build/fizzbuzz.jar 
 $ file ./build/fizzbuzz.jar 
 ./build/fizzbuzz.jar: Zip archive data, at least v2.0 to extract, compression method=deflate

21. Uber Jar $ java -jar ./build/fizzbuzz.jar --start 1 --end 15
 1
 2
 Buzz
 4
 Fizz
 Buzz
 7
 8
 Buzz
 Fizz
 11
 Buzz
 13
 14
 BuzzFizz

22. Native Image と Uber Jar の比較
23. Uber Jar (time -v の実行結果抜粋) $ /usr/bin/time -v java -jar ./build/fizzbuzz.jar --start 1 --end 10 
 1
 2
 Buzz
 4
 Fizz
 Buzz
 7
 8
 Buzz
 Fizz
 Command being timed: "java -jar ./build/fizzbuzz.jar --start 1 --end 10" 
 User time (seconds): 0.79
 System time (seconds): 0.13
 Percent of CPU this job got: 198%
 Elapsed (wall clock) time (h:mm:ss or m:ss): 0:00.46
 Maximum resident set size (kbytes): 92672

24. Native Image (time -v の実行結果抜粋) $ /usr/bin/time -v ./build/fizzbuzz --start 1 --end 10 
 1
 2
 Buzz
 4
 Fizz
 Buzz
 7
 8
 Buzz
 Fizz
 Command being timed: "./build/fizzbuzz --start 1 --end 10" 
 User time (seconds): 0.00
 System time (seconds): 0.00
 Percent of CPU this job got: 112%
 Elapsed (wall clock) time (h:mm:ss or m:ss): 0:00.00
 Maximum resident set size (kbytes): 26752

25. 比較 (time -v の実行結果抜粋) Command being timed: "./build/fizzbuzz --start 1 --end 10" 
 User time (seconds): 0.00
 System time (seconds): 0.00
 Percent of CPU this job got: 112%
 Elapsed (wall clock) time (h:mm:ss or m:ss): 0:00.00
 Maximum resident set size (kbytes): 26752
 Command being timed: "java -jar ./build/fizzbuzz.jar --start 1 --end 10" 
 User time (seconds): 0.79
 System time (seconds): 0.13
 Percent of CPU this job got: 198%
 Elapsed (wall clock) time (h:mm:ss or m:ss): 0:00.46
 Maximum resident set size (kbytes): 92672
 Uber Jar Native Image (速すぎて実行時間が “0.00” になっている)
26. 実行速度が速い！
27. Footprint も小さい！
28. すごい！
29. ところでみなさん
30. お気づきですか？
31. Fizz… Buzz… ??? $ ./build/fizzbuzz --start 1 --end 15 
 1
 2
 Buzz <-
 4
 Fizz <-
 Buzz <-
 7
 8
 Buzz <-
 Fizz <-
 11
 Buzz <-
 13
 14
 BuzzFizz <-

32. Fizz Buzz もしかして... 今回の LT にはレギュレーションがあります
33. Fizz Buzz 私たち... 今回の LT にはレギュレーションがあります
34. Fizz Buzz 今回の LT にはレギュレーションがあります もしかして... 入れ替わってる～～～！？
35. Dev Mode
36. Native Image はとてもすごいけど Build に時間がかかる...
37. ちょっとした修正でも動作確認のために 長めの Build 待ちが発生...
38. そんな時に便利なのが Dev Mode
39. Rebuild 無しで動的に修正内容を確認 できる！
40. quarkus dev コマンドで Dev Mode を起動 $ quarkus dev
 (omit)
 BUILD SUCCESSFUL in 6s 
 10 actionable tasks: 10 executed 
 Listening for transport dt_socket at address: 5005 
 1
 2
 Buzz
 
 (omit)
 
 98
 Buzz
 Fizz
 
 --
 Tests paused
 Press [space] to restart, [e] to edit command line args (currently ''), [r] to resume testing, [o] Toggle test output, [:] for the terminal, [h] for more options> 

41. TUI っぽいものでいい感じに操作できる $ quarkus dev
 (omit)
 BUILD SUCCESSFUL in 6s 
 10 actionable tasks: 10 executed 
 Listening for transport dt_socket at address: 5005 
 1
 2
 Buzz
 
 (omit)
 
 98
 Buzz
 Fizz
 
 --
 Tests paused
 Press [space] to restart, [e] to edit command line args (currently ''), [r] to resume testing, [o] Toggle test output, [:] for the terminal, [h] for more options> 

42. [e] を押して引数を変更し... --
 Tests paused
 Press [space] to restart, [e] to edit command line args (currently '--start 1 --end 10') , [r] to resume testing, [o] Toggle test output> 
 --
 Tests paused
 --start 1 --end 10 
 --
 Tests paused
 Press [space] to restart, [e] to edit command line args (currently '') , [r] to resume testing, [o] Toggle test output> 

43. スペースを押すと新しい引数で実行してくれる 1
 2
 Buzz
 4
 Fizz
 Buzz
 7
 8
 Buzz
 Fizz
 
 --
 Tests paused
 Press [space] to restart , [e] to edit command line args (currently '--start 1 --end 10'), [r] to resume testing, [o] Toggle test output> 

44. ソースコードを修正し保存した上で... $ git diff
 (omit)
 @@ -22,13 +22,13 @@ public class FizzBuzzOptions { 
 names = {"-f", "--fizz"}, 
 description = "Output for multiples of 3", 
 required = false, 
 - defaultValue = "Buzz") 
 + defaultValue = "Fizz") 
 String fizz;
 
 @CommandLine.Option( 
 names = {"-b", "--buzz"}, 
 description = "Output for multiples of 5", 
 required = false, 
 - defaultValue = "Fizz") 
 + defaultValue = "Buzz") 
 String buzz;
 } 

45. スペースを押すと修正後のコードを実行できる！ 1
 2
 Fizz
 4
 Buzz
 Fizz
 7
 8
 Fizz
 Buzz
 
 --
 Tests paused
 Press [space] to restart , [e] to edit command line args (currently '--start 1 --end 10'), [r] to resume testing, [o] Toggle test output> 

46. ちなみに
47. Web App だとこんな感じの UI が使える
48. まとめ
49. まとめ • SUPERSONIC (超音速) で SUBATOMIC (亜原子) な Java Framework！ • Java App を Native Image (実行可能ファイル) に Build することができる！ • Dev Mode を使うと、ソースコードの修正を (Rebuild 無し で) ｼｭｯ と確認できる！
50. Framework の名は
51. Quarkus
52. Thank you!