6.5840 Lab 1: MapReduce
In this lab you'll build a MapReduce system. You'll implement a worker process that calls application Map and Reduce functions and handles reading and writing files, and a coordinator process that hands out tasks to workers and copes with failed workers. You'll be building something similar to the MapReduce paper. (Note: this lab uses "coordinator" instead of the paper's "master".) You need to setup Go to do the labs. Fetch the initial lab software with git (a version control system). To learn more about git, look at the Pro Git book or the git user's manual. We supply you with a simple sequential mapreduce implementation in src/main/mrsequential.go. It runs the maps and reduces one at a time, in a single process. We also provide you with a couple of MapReduce applications: word-count in mrapps/wc.go, and a text indexer in mrapps/indexer.go. You can run word count sequentially as follows: mrsequential.go leaves its output in the file mr-out-0. The input is from the text files named pg-
6.5840 Lab 1: MapReduce 6.5840 - Spring 2026 6.5840 Lab 1: MapReduce Collaboration policy // Submit lab // Setup Go // Guidance // Piazza Introduction In this lab you'll build a MapReduce system. You'll implement a worker process that calls application Map and Reduce functions and handles reading and writing files, and a coordinator process that hands out tasks to workers and copes with failed workers. You'll be building something similar to the MapReduce paper . (Note: this lab uses "coordinator" instead of the paper's "master".) Getting started You need to setup Go to do the labs. Fetch the
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