Java Community | Help. Code. Learn.•7mo ago

Virtual threads

If I have the following implementation

@Configuration
@EnableAsync
public class VirtualThreadConfig {

    @Bean
    @Primary
    public TaskExecutor virtualThreadExecutor() {
        return new TaskExecutorAdapter(Executors.newVirtualThreadPerTaskExecutor());
    }
}

@Configuration
@EnableAsync
public class VirtualThreadConfig {

    @Bean
    @Primary
    public TaskExecutor virtualThreadExecutor() {
        return new TaskExecutorAdapter(Executors.newVirtualThreadPerTaskExecutor());
    }
}

Service

@Async
    public List<UserDto> getAllAsync() {

        UserDto[] users = restClient.get()
                .uri(baseUrl + "/users")
                .retrieve()
                .body(UserDto[].class);
        return List.of(users);
    }

@Async
    public List<UserDto> getAllAsync() {

        UserDto[] users = restClient.get()
                .uri(baseUrl + "/users")
                .retrieve()
                .body(UserDto[].class);
        return List.of(users);
    }

If Async already wraps the method in a CompletableFuture it is recommended not to rewrap it because it would be redundant. How I implement in the controller, I'm using java 21, version spring 3.5.0

@GetMapping
    public CompletableFuture<ResponseEntity<List<UserDto>>> getAll() {
        
    }

@GetMapping
    public CompletableFuture<ResponseEntity<List<UserDto>>> getAll() {
        
    }

13 Replies

JavaBot•7mo ago

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dan1st•7mo ago

Are you using a recent Spring version? If so, why are you not just enabling virtual threads in the application.properties and do everything synchronously?

pedroavilaOP•7mo ago

version spring 3.5.0 have example the configuration that solved my problem?

dan1st•7mo ago

Spring Boot 3.5.0 supports virtual threads in the way I mentioned if you set it in the application.properties, Spring should use virtual threads wherever it can (and where it makes sense)

pedroavilaOP•7mo ago

Is this VirtualThreadConfig implementation no longer necessary?

dan1st•7mo ago

no just add spring.threads.virtual.enabled to the application.properties and it configures everything necessary for virtual threads which is more than your config class

pedroavilaOP•7mo ago

 spring.threads.virtual.enabled=true

public List<UserDto> getAllAsync() {

        UserDto[] users = restClient.get()
                .uri(baseUrl + "/users")
                .retrieve()
                .body(UserDto[].class);
        return List.of(users);
    }

@GetMapping
    public ResponseEntity<?> getAll() {
        try {
            List<UserDto> users = serviceUser.getAllAsync();

            return ResponseEntity.ok(users);
        } catch (Exception ex) {
            ex.printStackTrace();
            return ResponseEntity.status(500).body(null);
        }
    }

 spring.threads.virtual.enabled=true

public List<UserDto> getAllAsync() {

        UserDto[] users = restClient.get()
                .uri(baseUrl + "/users")
                .retrieve()
                .body(UserDto[].class);
        return List.of(users);
    }

@GetMapping
    public ResponseEntity<?> getAll() {
        try {
            List<UserDto> users = serviceUser.getAllAsync();

            return ResponseEntity.ok(users);
        } catch (Exception ex) {
            ex.printStackTrace();
            return ResponseEntity.status(500).body(null);
        }
    }

In this magical way I would already be working with virtual threads and my methods would be asynchronous and non-blocking.

dan1st•7mo ago

The code would be blocking but it doesn't block platform/OS threadsso you don't have the scalability issues/it's as if you'd write asynchronous code and I would rename the getAllAsync method

pedroavilaOP•7mo ago

Wow, great how wonderful is spring 3+ and java 21 with the virtual threads very magical compared to the traditional threads that you had to configure the thread and work with CompletableFuture, the new implementation is cleaner

dan1st•7mo ago

yep

pedroavilaOP•7mo ago

Thanks very @dan1st | Daniel

JavaBot•7mo ago

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