Hi,

Problem appeared with chapter 9 data.
I had to use export MAVEN_OPTS="-Xmx8192m -XX:MaxPermSize=256m" to be able to build entire solution.

With lower heap size I've ended with below error
I wonder if it makes sens to add information about memory requirement for build in some README.

[INFO] ------------------------------------------------------------------------
[INFO] Reactor Summary:
[INFO]
[INFO] Advanced Analytics with Spark 2.0.0 ................ SUCCESS [ 2.847 s]
[INFO] Introduction to Data Analysis with Scala and Spark 2.0.0 SUCCESS [ 6.911 s]
[INFO] Recommender Engines with Audioscrobbler data 2.0.0 . SUCCESS [ 0.210 s]
[INFO] Covtype with Random Decision Forests 2.0.0 ......... SUCCESS [ 0.194 s]
[INFO] Anomaly Detection with K-means 2.0.0 ............... SUCCESS [ 0.229 s]
[INFO] Wikipedia Latent Semantic Analysis 2.0.0 ........... SUCCESS [ 20.339 s]
[INFO] Network Analysis with GraphX 2.0.0 ................. SUCCESS [ 2.014 s]
[INFO] Temporal and Geospatial Analysis 2.0.0 ............. SUCCESS [ 0.361 s]
[INFO] Value at Risk through Monte Carlo Simulation 2.0.0 . FAILURE [06:44 min]
[INFO] Genomics Analysis with ADAM 2.0.0 .................. SKIPPED
[INFO] Simple Spark Project 0.1.0 ......................... SKIPPED
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 07:20 min
[INFO] Finished at: 2021-05-19T06:25:27-07:00
[INFO] ------------------------------------------------------------------------
[ERROR] Java heap space -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/OutOfMemoryError