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title: Advanced Mule Concepts
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# Advanced Mule Concepts

> For the full documentation index, see: https://docs.mulesoft.com/llms.txt

After you become familiar with the basics of Mule application development and Mule runtime engine
(Mule) concepts, you can focus on more advanced features, such as the execution engine, the
classloading isolation mechanism, and distributed file polling.

Learn about the [execution engine](https://docs.mulesoft.com/mule-runtime/4.3/execution-engine) to understand how Mule runtime engine processes
the operations in a Mule application flow, and to understand how to change the thread pools if
needed. Mule runtime engine uses execution metadata provided by operations in a flow to perform
autotuning.

The [classloading isolation](https://docs.mulesoft.com/mule-runtime/4.3/about-classloading-isolation) mechanism implemented in Mule 4 is
designed to make upgrades easier by preventing components from exposing their internal resources.
All components interact with each other through their defined APIs so that only exposed resources
can be accessed by other components. Classloading isolation ensures that a component’s internal
content is protected and can be changed any time, without affecting other components.

Mule 4 supports [distributed file polling](https://docs.mulesoft.com/mule-runtime/4.3/distributed-file-polling), which allows connectors to
read files from certain directories as they are created. Distributed file polling also makes it
possible to poll files in all cluster nodes.

Mule 4 also supports [distributed locking](https://docs.mulesoft.com/mule-runtime/4.3/distributed-locking), which provides the ability to
create locks for synchronizing access to resources within Mule components.

You can refer to the [Javadocs](https://docs.mulesoft.com/mule-runtime/4.3/mule-4-api-javadoc) for Mule Kernel (the community edition of Mule
runtime engine) to learn definitions for classes, fields, and data types.

You can see a list of [third-party software](https://docs.mulesoft.com/mule-runtime/4.3/third-party-software-in-mule) that is included as part
of Mule runtime engine as internal dependencies.