Difference between revisions of "MapReduce Frameworks Lab"
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| + | [[Bottleneck_MapReduce_Framework_Assignment|Bottleneck MapReduce Framework]] | ||
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| + | [[Matrix_MapReduce_Framework_Assignment|Matrix MapReduce Framework]] | ||
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credit for this assignment: Finn Voichick and Dennis Cosgrove | credit for this assignment: Finn Voichick and Dennis Cosgrove | ||
=Motivation= | =Motivation= | ||
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* [[#Optional_Warm_Up]] | * [[#Optional_Warm_Up]] | ||
* [[#Bottlenecked_MapReduce_Framework]] | * [[#Bottlenecked_MapReduce_Framework]] | ||
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* [[Cholera_MapReduce_Application]] | * [[Cholera_MapReduce_Application]] | ||
* [[#Matrix_MapReduce_Framework]] | * [[#Matrix_MapReduce_Framework]] | ||
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{{Warning| Reminder: our course libraries consistently specify max to be exclusive. This includes the parallel forall loop.}} | {{Warning| Reminder: our course libraries consistently specify max to be exclusive. This includes the parallel forall loop.}} | ||
| − | With this method, you will map all of the elements of an array of data into a new array of equivalent size consisting of | + | With this method, you will map all of the elements of an array of data into a new array of equivalent size consisting of Lists of key value pairs. We will leverage the Mapper which is a field/instance variable on this BottleneckedFramework instance. When invoking the mapper's map method with an element of the input array and a BiConsumer which will accept each key and value passed to it, adding a KeyValuePair to its List. This list should then be added to the array of lists you previously defined, therefore completing the mapping stage of MapReduce. This should all be done in parallel. |
Hint: you should create an array of lists equivalent in size to the original array. Each list will contain all of the emitted (key,value) pairs for its item. | Hint: you should create an array of lists equivalent in size to the original array. Each list will contain all of the emitted (key,value) pairs for its item. | ||
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In this method, you will take in the array of lists you previously created and accumulate the key value pairs in the lists into a newly defined map. To help deal with this issue, you must make use of the Collector provided to you. More specifically, access the accumulator in the collector by calling the <code>accumulator()</code> method and accept the key/value pair when you add it to the map. You probably noticed that the method must return a map of <K, A>, which differs from the <K, V> generics fed into the method. The framework is designed this way as the data originally fed into the mapping stage can be collected into a mutable container before reaching the finish/reduce stage. In order to access the correct value for the map if the key has no associated value yet, use the supplier associated with the Collector with the <code>supplier()</code> method. | In this method, you will take in the array of lists you previously created and accumulate the key value pairs in the lists into a newly defined map. To help deal with this issue, you must make use of the Collector provided to you. More specifically, access the accumulator in the collector by calling the <code>accumulator()</code> method and accept the key/value pair when you add it to the map. You probably noticed that the method must return a map of <K, A>, which differs from the <K, V> generics fed into the method. The framework is designed this way as the data originally fed into the mapping stage can be collected into a mutable container before reaching the finish/reduce stage. In order to access the correct value for the map if the key has no associated value yet, use the supplier associated with the Collector with the <code>supplier()</code> method. | ||
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[[File:Bottlenecked accumulate all.png|400px]] [https://docs.google.com/presentation/d/1Gtpj6_5_8imUMccpwxmfrOxKSED791OKl4lZR6G2Bm4/pub?start=false&loop=false&delayms=3000&slide=id.g7ea283730e_0_165 slide] | [[File:Bottlenecked accumulate all.png|400px]] [https://docs.google.com/presentation/d/1Gtpj6_5_8imUMccpwxmfrOxKSED791OKl4lZR6G2Bm4/pub?start=false&loop=false&delayms=3000&slide=id.g7ea283730e_0_165 slide] | ||
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[[File:Matrix map accumulate art.png|400px]] [https://docs.google.com/presentation/d/1bSLKsI5u2e_tFc0d-RSb0BIDwA-kD75U6yXfxvpMf6Y/pub?start=false&loop=false&delayms=3000&slide=id.g7ebdc248f6_0_388 slide] | [[File:Matrix map accumulate art.png|400px]] [https://docs.google.com/presentation/d/1bSLKsI5u2e_tFc0d-RSb0BIDwA-kD75U6yXfxvpMf6Y/pub?start=false&loop=false&delayms=3000&slide=id.g7ebdc248f6_0_388 slide] | ||
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===combineAndFinishAll=== | ===combineAndFinishAll=== | ||
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* Correct mapAndAccumulateAll (30) | * Correct mapAndAccumulateAll (30) | ||
* Correct combineAndFinishAll (30) | * Correct combineAndFinishAll (30) | ||
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