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This is the Map-Reduce homework for PingCAP Talent Plan Online of week 2.

There is a uncompleted Map-Reduce framework, you should complete it and use it to extract the 10 most frequent URLs from data files.

Getting familiar with the source

The simple Map-Reduce framework is defined in mapreduce.go.

It is uncompleted and you should fill your code below comments YOUR CODE HERE.

The map and reduce function are defined as same as MIT 6.824 lab 1.

type ReduceF func(key string, values []string) string
type MapF func(filename string, contents string) []KeyValue

There is an example in urltop10_example.go which is used to extract the 10 most frequent URLs.

After completing the framework, you can run this example by make test_example.

And then please implement your own MapF and ReduceF in urltop10.go to accomplish this task.

After filling your code, please use make test_homework to test.

All data files will be generated at runtime, and you can use make cleanup to clean all test data.

Please output URLs by lexicographical order and ensure that your result has the same format as test data so that you can pass all tests.

Each test cases has different data distribution and you should take it into account.

Requirements and rating principles

  • (40%) Performs better than urltop10_example.
  • (20%) Pass all test cases.
  • (30%) Have a document to describe your idea and record the process of performance optimization (both the framework and your own code) with pprof.
  • (10%) Have a good code style.

NOTE: go 1.12 is required

How to use

Fill your code below comments YOUR CODE HERE in mapreduce.go to complete this framework.

Implement your own MapF and ReduceF in urltop10.go and use make test_homework to test it.

There is a builtin unit test defined in urltop10_test.go, however, you still can write your own unit tests.

How to run example:

make test_example

How to test your implementation:

make test_homework

How to clean up all test data:

make cleanup

How to generate test data again:

make gendata
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