Spring Task Scheduler vs. Java's ScheduledExecutorService

Question

I have a requirement to create a task scheduler with 10 threads that we need to fire at the same time and each thread will come back with a status of complete or failed. Based on the result of the thread, we will make a db call and fetch the data from db. The application is already configured with Spring Framework. I understand that spring provides task scheduler, but not sure how to use it, spring newbie needs help. How about java's ScheduledExecutorService, can we use that? What advantage we will get one over the other? Is there a better alternative to Spring task scheduler and Java's ScheduledExecutorService?

Answer 1

Spring TaskExecutor is actually identical to java Executor interface. After Spring 2.0 TaskExecutor has been introduced to add abstraction to the Java's Executor, so that it will hide implementation details between Java SE different versions and EE environments.

As you have already Spring environment, I'd strongly recommend to use spring schedulers. Later on if there will be need you can give other Spring components an abstraction for thread pooling, etc.

Also there are some pre-built implementations of TaskExecutor, which is ideal, as you don't have to care about the details and implementation by your own.

Answer 2

The simplest way is to use the provided task tags in the spring config. Notice the 'task' namespace below

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xmlns:ctx="http://www.springframework.org/schema/context"
       xmlns:task="http://www.springframework.org/schema/task"
       xmlns:util="http://www.springframework.org/schema/util"
       xsi:schemaLocation="
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd
        http://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task-3.2.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd
        http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd
        http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.2.xsd
">

once you've done that you can use

<task:scheduler id="taskScheduler" pool-size="4"/>
<task:scheduled-tasks scheduler="taskScheduler">
   <task:scheduled ref="someBean" method="someMethod" fixed-rate="21600000" initial-delay="60000"/>
</task:scheduled-tasks>

etc. your actual scheduled task is a bean with a method on it that gets called. You can schedule it on a fixed delay or on a cron etc.

you can also declare executors in the config like this :

<bean id="taskExecutor" class="org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor">
        <description>A task pool for general use</description>
        <property name="corePoolSize" value="150" />
        <property name="maxPoolSize" value="200" />
        <property name="queueCapacity" value="10" />
        <property name="keepAliveSeconds" value="0"/>
        <property name="waitForTasksToCompleteOnShutdown" value="false"/>
    </bean>

You can use an executor to execute a pool of concurrent tasks (inject that bean into your bean and look at what it provides).