Understanding the BitBake tool
The BitBake task scheduler started as a fork from Portage, the package management system used in the Gentoo distribution. However, the two projects diverged significantly due to different use cases. The Yocto Project and the OpenEmbedded Project are intensive users of BitBake. It remains a separate and independent project with its own development cycle and mailing list (bitbake-devel@lists.openembedded.org).
BitBake is a tool similar to GNU Make. As discussed in Chapter 1, Meeting the Yocto Project, BitBake is a task executor and scheduler that parses Python and Shell Script mixed code.
Therefore, BitBake is responsible for running as many tasks as possible in parallel while ensuring they are run respecting their dependencies.