Chapter 8. Tuning, debugging, and testing

This chapter covers

  • Measuring and tuning MapReduce execution times
  • Debugging your applications
  • Testing tips to improve the quality of your code

Imagine you’ve written a new piece of MapReduce code, and you’re executing it on your shiny new cluster. You’re surprised to learn that despite having a good-sized cluster, your job is running significantly longer than you expected. You’ve obviously hit a performance issue with your job, but how do you figure out where the problem lies?

This chapter starts out by reviewing common performance problems in Map-Reduce, such as the lack of data locality and running with too many mappers. This tuning section also examines some enhancements that you can make to your ...

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