A Common-Sense Guide to Data Structures and Algorithms in Python, Volume 1: Apache Giraph has been retired (page364)
On page 364 there’s a reference to various graph databases including Apache Giraph. Unfortunately, Apache Giraph has been retired. Details are available on the application’s Attic page:
Apache Giraph moved into the Attic in 2023-09. Apache Giraph was an iterative graph processing system built for high scalability.
The documentation is still accessible, and may continue to be valuable, but you might consider whether you wish to keep this reference in the text, remove it, or replace it with a different application (if there is one).