This version is still in development and is not considered stable yet. For the latest stable version, please use Spring Boot 3.4.0!spring-doc.cn

Task Execution and Scheduling

In the absence of an Executor bean in the context, Spring Boot auto-configures an AsyncTaskExecutor. When virtual threads are enabled (using Java 21+ and spring.threads.virtual.enabled set to true) this will be a SimpleAsyncTaskExecutor that uses virtual threads. Otherwise, it will be a ThreadPoolTaskExecutor with sensible defaults. In either case, the auto-configured executor will be automatically used for:spring-doc.cn

asynchronous task execution (@EnableAsync)spring-doc.cn
Spring for GraphQL’s asynchronous handling of Callable return values from controller methodsspring-doc.cn
Spring MVC’s asynchronous request processingspring-doc.cn
Spring WebFlux’s blocking execution supportspring-doc.cn

If you have defined a custom Executor in the context, both regular task execution (that is @EnableAsync) and Spring for GraphQL will use it. However, the Spring MVC and Spring WebFlux support will only use it if it is an AsyncTaskExecutor implementation (named applicationTaskExecutor). Depending on your target arrangement, you could change your Executor into an AsyncTaskExecutor or define both an AsyncTaskExecutor and an AsyncConfigurer wrapping your custom Executor.spring-doc.cn

The auto-configured ThreadPoolTaskExecutorBuilder allows you to easily create instances that reproduce what the auto-configuration does by default.spring-doc.cn

When a ThreadPoolTaskExecutor is auto-configured, the thread pool uses 8 core threads that can grow and shrink according to the load. Those default settings can be fine-tuned using the spring.task.execution namespace, as shown in the following example:spring-doc.cn

Propertiesspring-doc.cn
YAMLspring-doc.cn

spring.task.execution.pool.max-size=16
spring.task.execution.pool.queue-capacity=100
spring.task.execution.pool.keep-alive=10s

spring:
  task:
    execution:
      pool:
        max-size: 16
        queue-capacity: 100
        keep-alive: "10s"

This changes the thread pool to use a bounded queue so that when the queue is full (100 tasks), the thread pool increases to maximum 16 threads. Shrinking of the pool is more aggressive as threads are reclaimed when they are idle for 10 seconds (rather than 60 seconds by default).spring-doc.cn

A scheduler can also be auto-configured if it needs to be associated with scheduled task execution (using @EnableScheduling for instance).spring-doc.cn

If virtual threads are enabled (using Java 21+ and spring.threads.virtual.enabled set to true) this will be a SimpleAsyncTaskScheduler that uses virtual threads. This SimpleAsyncTaskScheduler will ignore any pooling related properties.spring-doc.cn

If virtual threads are not enabled, it will be a ThreadPoolTaskScheduler with sensible defaults. The ThreadPoolTaskScheduler uses one thread by default and its settings can be fine-tuned using the spring.task.scheduling namespace, as shown in the following example:spring-doc.cn

Propertiesspring-doc.cn
YAMLspring-doc.cn

spring.task.scheduling.thread-name-prefix=scheduling-
spring.task.scheduling.pool.size=2

spring:
  task:
    scheduling:
      thread-name-prefix: "scheduling-"
      pool:
        size: 2

A ThreadPoolTaskExecutorBuilder bean, a SimpleAsyncTaskExecutorBuilder bean, a ThreadPoolTaskSchedulerBuilder bean and a SimpleAsyncTaskSchedulerBuilder are made available in the context if a custom executor or scheduler needs to be created. The SimpleAsyncTaskExecutorBuilder and SimpleAsyncTaskSchedulerBuilder beans are auto-configured to use virtual threads if they are enabled (using Java 21+ and spring.threads.virtual.enabled set to true).spring-doc.cn