Better docs on "inter-op" with @Async

[gregjotau]

As far as I understand when using Virtual threads you should not use Thread pools like this:

@Configuration
class ServiceExecutorConfig : AsyncConfigurer {
    override fun getAsyncExecutor(): Executor {
        val taskExecutor = ThreadPoolTaskExecutor().apply {
            corePoolSize = 15
            maxPoolSize = 50
            setQueueCapacity(100)
            initialize()
        }
        return DelegatingSecurityContextAsyncTaskExecutor(taskExecutor)
    }
}

But instead something like:

@Configuration
@EnableAsync
class AsyncConfig(
    private val builder: SimpleAsyncTaskExecutorBuilder
) {

    @Bean(name = ["secExecutor"])
    fun secExecutor(): AsyncTaskExecutor {
        // With spring.threads.virtual.enabled=true this builder creates
        // a SimpleAsyncTaskExecutor that uses a *new virtual thread per task*.
        val delegate = builder
            .threadNamePrefix("async-")
            .build()

        return DelegatingSecurityContextAsyncTaskExecutor(delegate)
    }
}

I'm trying to find good official docs on how to handle this, the first results are blogs recommending the ThreadPoolTaskExecutor approach.

I also find this, which does not cover a simple way of making Spring security work with Async out of the box:

https://docs.spring.io/spring-security/reference/features/integrations/concurrency.html

I'm not sure if this is something that it would make sense if the framework just solved with reasonable defaults?

[gregjotau]

If the docs are not covering it, AI will just recommend whatever it finds online 😅 Which might be far from optimal:

If I do not misunderstand pron98 (OpenJDK dev) says we should basically never pool threads like this examples show (when using virtual threads)