When is it appropriate to use Apache Mahout?

You should consider the following aspects before making a decision to use Apache Mahout as your machine learning library:

• Are you looking for a machine learning algorithm for industry use with performance as a critical evaluation factor?
• Are you looking for a free and open source solution?
• Is your dataset large and growing at an alarming rate? (MATLAB, Weka, Octave, and R can be used to process KBs and MBs of data, but if your data volume is growing up to the GB level, then it is better to use Mahout.)
• Do you want batch data processing as opposed to real-time data processing?
• Are you looking for a mature library, which has been there in the market for a few years?

If all or most of the preceding considerations are met, then Mahout is the right solution for you.