flowchart LR
    subgraph Client
        C[HTTP Client]
    end
    subgraph "Spring Boot :8080"
        R[Controller]
        R --> E["/api/service\nExecutorService"]
        R --> S["/api/service/structured\nStructuredTaskScope"]
        E --> VT1[Virtual Thread 1]
        E --> VT2[Virtual Thread 2]
        S --> VT3[Virtual Thread 3]
        S --> VT4[Virtual Thread 4]
    end
    VT1 --> A[callServiceA]
    VT2 --> B[callServiceB]
    VT3 --> A
    VT4 --> B
    C --> R

• ExecutorService path: Two tasks submitted to a virtual-thread executor; Future.get(2, SECONDS) with cancel on timeout.
• StructuredTaskScope path: ShutdownOnFailure scope, fork for each call, joinUntil(deadline), then throwIfFailed() and collect results.

• JDK 21 (for local run and tests)
• Docker and Docker Compose (for containerized run)

git clone https://github.com/NullPoint3rDev/virtual-threads.git
cd virtual-threads
docker compose up --build

• API: http://localhost:8081/api/service and http://localhost:8081/api/service/structured
• Health: http://localhost:8081/actuator/health

Port 8081 is used by default to avoid clashes with other apps on 8080. Change docker-compose.yml to "8080:8080" if you prefer.

./gradlew bootRun

Then open http://localhost:8080/api/service (and /api/service/structured).
StructuredTaskScope is a preview API in Java 21; the build enables --enable-preview for compile and run.

Example response:

{"serviceA":"result-A","serviceB":"result-B"}

Health check: GET /actuator/health → {"status":"UP"}.

./gradlew test

• VirtualThreadsServiceTest — unit tests for fetchWithVirtualThreads() and fetchWithStructuredConcurrency() with a real virtual-thread executor.
• VirtualThreadsControllerTest — @SpringBootTest + MockMvc for both endpoints.

Preview is enabled for the test JVM via jvmArgs("--enable-preview") in build.gradle.kts.

MIT