Before you can start coding in Maven, either to search and fix a bug or to do any enhancements, you will probably be looking for a starting point what code gets executed during a mvn install or a similar call.
This document will provide a walk-through of the Maven source code. Please refer to xxx about how to checkout the sources and build Maven yourself.
When called from the command line, the main method of the class org.apache.maven.cli.MavenCli (as in Command Line Interface) will be called.
The sequence of action is roughly:
This is where the command line specific invocation ends.
The DefaultMaven instantiates a bunch of objects which interact during the execution of a request.
The session is executed by the LifecycleExecutor (org.apache.maven.lifecycle.LifecycleExecutor).
Many users of Maven associate the reactor with multiple project setups, maybe because in a multi-module project, you will see a reactor build order as part of the Maven output. But the ReactorManager is not only used in case of multi-module projects, but also for single projects.