Does reactor spawn a subprocess for each submodule?

[Tracy Hartford]

I am working on a large multi-module project, and I need to know how the
reactor works when I invoke a maven goal on the parent POM. I know that
Maven adds all the submodule POMs into the Reactor, which analyzes the
dependencies between them, and determines the build order. I understand
that the Reactor then "effectively executes" the goal for each
submodule. What I need to know is, when the Reactor executes the goal
for a given submodule, does it spawn a child process to do so, or does
it execute in the current process? If it execute in the current process,
is there a way to force it to spawn a new process first?