Problem Statement:

AEM Schedulers are commonly used to run bulk tasks at an off time (nonbusiness hours) and some tasks are run periodically to fetch results cached and fetched by the front end.

How can we make sure bulk tasks won’t impact AEM performance (CPU or Heap memory) / throttle the system?

Introduction:

In Computer Software, Scheduling is a paradigm of planning for the execution of a task at a certain point in time and it can be broadly classified into two types:

1. Scheduled Task – executing once at a particular future point in time

2. Frequent scheduling – repeat periodically at a fixed interval

The use case for the scheduler:

1. Sitemap generation

2. Synching product data from AEM Commerce

3. Fetch DB content and place it in the repository to be picked up by frontend and in turn cached in Dispatcher

4. Fetch Stats or reports and place them in the repository to be picked up by frontend and in turn cached in Dispatcher

ACS Commons Throttled Task Runner is built on Java management API for managing and monitoring the Java VM and can be used to pause tasks and terminate the tasks based on stats.

Throttled Task Runner (a managed thread pool) provides a convenient way to run many AEM-specific activities in bulk it basically checks for the Throttled Task Runner bean and gets current running stats of the actual work being done.

OSGi Configuration:

The Throttled Task Runner is OSGi configurable, but please note that changing configuration while work is being processed results in resetting the worker pool and can lose active work.

Max threads: Recommended not to exceed the number of CPU cores. Default 4.

Max CPU %: Used to throttle activity when CPU exceeds this amount. Range is 0..1; -1 means disable this check.

Max Heap %: Used to throttle activity when heap usage exceeds this amount. Range is 0..1; -1 means disable this check.

Cooldown time: Time to wait for CPU/MEM cooldown between throttle checks (in milliseconds)

Watchdog time: Maximum time allowed (in ms) per action before it is interrupted forcefully.

JMX MBeans

Throttled Task Runner MBean

This is the core worker pool. All action managers share the same task runner pool, at least in the current implementation. The task runner can be paused or halted entirely, throwing out any unfinished work.

How to use ACS Commons throttled task runner

Add the following dependency to your pom

<dependency>
     <groupId>com.adobe.acs</groupId>
     <artifactId>acs-aem-commons-bundle</artifactId>
     <version>5.0.4</version>
     <scope>provided</scope>
 </dependency>

Create a scheduler and call the service as shown below:

inside the run, method check for the Low CPU and Low memory before starting your task to avoid performance impact on the system

For the best practices on AEM Scheduler please refer to the link