Spring @Async limit number of threads

Question

My question is very similar to this one : @Async prevent a thread to continue until other thread have finished

Basically i need run ~ hundreds of computations in more threads. I want to run only some amount of parallel threads e.g. 5 threads with 5 computationis in paralell.

I am using spring framework and @Async option is natural choice. I do not need full-featured JMS queue, that`s a bit overhead for me.

Any ideas ? Thank you

Answer 1

Have you checked out Task Executor? You can define a Thread Pool, with a maximum number of threads to execute your tasks.

If you want to use it with @Async, use this in your spring-config:

<task:annotation-driven executor="myExecutor" scheduler="myScheduler"/>

<task:executor id="myExecutor" pool-size="5"/>

<task:scheduler id="myScheduler" pool-size="10"/>

Full reference here (25.5.3). Hope this helps.

Answer 2

If you are using Spring's Java-configuration, your config class needs to implements AsyncConfigurer:

@Configuration
@EnableAsync
public class AppConfig implements AsyncConfigurer {

    [...]

    @Override
    public Executor getAsyncExecutor() {
        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
        executor.setCorePoolSize(2);
        executor.setMaxPoolSize(5);
        executor.setQueueCapacity(50);
        executor.setThreadNamePrefix("MyExecutor-");
        executor.initialize();
        return executor;
    }
}

See @EnableAsync documentation for more details : http://docs.spring.io/spring/docs/3.1.x/javadoc-api/org/springframework/scheduling/annotation/EnableAsync.html