Why do we need Parallel Processing:
Parse a large book
An example works well to ilustrate this. You have a large document and your job is to perform a frequency analysis of all the words used in it.
The sequential approach
You can do this sequentially by getting your fastest machine (you’ve got plenty lying around) and running over the text from start to finish maintaining a hash map of every word you find (the key) and incrementing the frequency (value) every time you parse a word. Simple, straightforward and slow.
The MapReduce approach
Approaching this from a different perspective, you note that you have all these spare machines lying around and you could split this task up into chunks. Give each machine a 1Mb block of text to parse into a hash map and then collate all the hash maps from each into a single result. This is a layered MapReduce solution.
The process of reading a line of text and gathering the words is the Map phase (you create a simple map representing the words in the line with their frequency 1,2,3 etc), then the Reduce phase is when each machine collates their line maps into a single aggregate map.
The overall solution comes from a further Reduce phase where all the aggregate maps are aggregated (that word again) into a final map. Slightly more complex, massively parallel and quick.
Please find the list of Distributed Programming.
|Apache MapReduce||MapReduce is a programming model for processing large data sets with a parallel, distributed algorithm on a cluster. Apache MapReduce was derived from Google MapReduce: Simplified Data Processing on Large Clusters paper. The current Apache MapReduce version is built over Apache YARN Framework. YARN stands for “Yet-Another-Resource-Negotiator”. It is a new framework that facilitates writing arbitrary distributed processing frameworks and applications. YARN’s execution model is more generic than the earlier MapReduce implementation. YARN can run applications that do not follow the MapReduce model, unlike the original Apache Hadoop MapReduce (also called MR1). Hadoop YARN is an attempt to take Apache Hadoop beyond MapReduce for data-processing.||1. Apache MapReduce
2. Google MapReduce paper
3. Writing YARN applications
|Apache Pig||Pig provides an engine for executing data flows in parallel on Hadoop. It includes a language, Pig Latin, for expressing these data flows. Pig Latin includes operators for many of the traditional data operations (join, sort, filter, etc.), as well as the ability for users to develop their own functions for reading, processing, and writing data. Pig runs on Hadoop. It makes use of both the Hadoop Distributed File System, HDFS, and Hadoop’s processing system, MapReduce.
Pig uses MapReduce to execute all of its data processing. It compiles the Pig Latin scripts that users write into a series of one or more MapReduce jobs that it then executes. Pig Latin looks different from many of the programming languages you have seen. There are no if statements or for loops in Pig Latin. This is because traditional procedural and object-oriented programming languages describe control flow, and data flow is a side effect of the program. Pig Latin instead focuses on data flow.
2.Pig examples by Alan Gates
|JAQL||JAQL is a functional, declarative programming language designed especially for working with large volumes of structured, semi-structured and unstructured data. As its name implies, a primary use of JAQL is to handle data stored as JSON documents, but JAQL can work on various types of data. For example, it can support XML, comma-separated values (CSV) data and flat files. A “SQL within JAQL” capability lets programmers work with structured SQL data while employing a JSON data model that’s less restrictive than its Structured Query Language counterparts.
Specifically, Jaql allows you to select, join, group, and filter data that is stored in HDFS, much like a blend of Pig and Hive. Jaql’s query language was inspired by many programming and query languages, including Lisp, SQL, XQuery, and Pig.
JAQL was created by workers at IBM Research Labs in 2008 and released to open source. While it continues to be hosted as a project on Google Code, where a downloadable version is available under an Apache 2.0 license, the major development activity around JAQL has remained centered at IBM. The company offers the query language as part of the tools suite associated with InfoSphere BigInsights, its Hadoop platform. Working together with a workflow orchestrator, JAQL is used in BigInsights to exchange data between storage, processing and analytics jobs. It also provides links to external data and services, including relational databases and machine learning data.
|1. JAQL in Google Code
2. What is Jaql? by IBM
|Apache Spark||Data analytics cluster computing framework originally developed in the AMPLab at UC Berkeley. Spark fits into the Hadoop open-source community, building on top of the Hadoop Distributed File System (HDFS). However, Spark provides an easier to use alternative to Hadoop MapReduce and offers performance up to 10 times faster than previous generation systems like Hadoop MapReduce for certain applications.
Spark is a framework for writing fast, distributed programs. Spark solves similar problems as Hadoop MapReduce does but with a fast in-memory approach and a clean functional style API. With its ability to integrate with Hadoop and inbuilt tools for interactive query analysis (Shark), large-scale graph processing and analysis (Bagel), and real-time analysis (Spark Streaming), it can be interactively used to quickly process and query big data sets.
To make programming faster, Spark provides clean, concise APIs in Scala, Java and Python. You can also use Spark interactively from the Scala and Python shells to rapidly query big datasets. Spark is also the engine behind Shark, a fully Apache Hive-compatible data warehousing system that can run 100x faster than Hive.
|1. Apache Spark
2. Mirror of Spark on Github
|Apache Flink||Apache Flink (formerly called Stratosphere) features powerful programming abstractions in Java and Scala, a high-performance runtime, and automatic program optimization. It has native support for iterations, incremental iterations, and programs consisting of large DAGs of operations.
Flink is a data processing system and an alternative to Hadoop’s MapReduce component. It comes with its own runtime, rather than building on top of MapReduce. As such, it can work completely independently of the Hadoop ecosystem. However, Flink can also access Hadoop’s distributed file system (HDFS) to read and write data, and Hadoop’s next-generation resource manager (YARN) to provision cluster resources. Since most Flink users are using Hadoop HDFS to store their data, it ships already the required libraries to access HDFS.
|1. Apache Flink incubator page
2. Stratosphere site
|AMPLab SIMR||Apache Spark was developed thinking in Apache YARN. However, up to now, it has been relatively hard to run Apache Spark on Hadoop MapReduce v1 clusters, i.e. clusters that do not have YARN installed. Typically, users would have to get permission to install Spark/Scala on some subset of the machines, a process that could be time consuming. SIMR allows anyone with access to a Hadoop MapReduce v1 cluster to run Spark out of the box. A user can run Spark directly on top of Hadoop MapReduce v1 without any administrative rights, and without having Spark or Scala installed on any of the nodes.||1. SIMR on GitHub|
|Facebook Corona||“The next version of Map-Reduce” from Facebook, based in own fork of Hadoop. The current Hadoop implementation of the MapReduce technique uses a single job tracker, which causes scaling issues for very large data sets. The Apache Hadoop developers have been creating their own next-generation MapReduce, called YARN, which Facebook engineers looked at but discounted because of the highly-customised nature of the company’s deployment of Hadoop and HDFS. Corona, like YARN, spawns multiple job trackers (one for each job, in Corona’s case).||TODO|
|Apache Twill||Twill is an abstraction over Apache Hadoop® YARN that reduces the complexity of developing distributed applications, allowing developers to focus more on their business logic. Twill uses a simple thread-based model that Java programmers will find familiar. YARN can be viewed as a compute fabric of a cluster, which means YARN applications like Twill will run on any Hadoop 2 cluster.
YARN is an open source application that allows the Hadoop cluster to turn into a collection of virtual machines. Weave, developed by Continuuity and initially housed on Github, is a complementary open source application that uses a programming model similar to Java threads, making it easy to write distributed applications. In order to remove a conflict with a similarly named project on Apache, called “Weaver,” Weave’s name changed to Twill when it moved to Apache incubation.
Twill functions as a scaled-out proxy. Twill is a middleware layer in between YARN and any application on YARN. When you develop a Twill app, Twill handles APIs in YARN that resemble a multi-threaded application familiar to Java. It is very easy to build multi-processed distributed applications in Twill.
|1. Apache Twill Incubator|
|Damballa Parkour||Library for develop MapReduce programs using the LISP like language Clojure. Parkour aims to provide deep Clojure integration for Hadoop. Programs using Parkour are normal Clojure programs, using standard Clojure functions instead of new framework abstractions. Programs using Parkour are also full Hadoop programs, with complete access to absolutely everything possible in raw Java Hadoop MapReduce.||1. Parkour GitHub Project|
|Apache Hama||Apache Top-Level open source project, allowing you to do advanced analytics beyond MapReduce. Many data analysis techniques such as machine learning and graph algorithms require iterative computations, this is where Bulk Synchronous Parallel model can be more effective than “plain” MapReduce.||1. Hama site|
|Datasalt Pangool||A new MapReduce paradigm. A new API for MR jobs, in higher level than Java.||TODO|
|Apache Tez||Tez is a proposal to develop a generic application which can be used to process complex data-processing task DAGs and runs natively on Apache Hadoop YARN. Tez generalizes the MapReduce paradigm to a more powerful framework based on expressing computations as a dataflow graph. Tez is not meant directly for end-users – in fact it enables developers to build end-user applications with much better performance and flexibility. Hadoop has traditionally been a batch-processing platform for large amounts of data. However, there are a lot of use cases for near-real-time performance of query processing. There are also several workloads, such as Machine Learning, which do not fit will into the MapReduce paradigm. Tez helps Hadoop address these use cases. Tez framework constitutes part of Stinger initiative (a low latency based SQL type query interface for Hadoop based on Hive).||1. Apache Tez Incubator
2. Hortonworks Apache Tez page
|Apache DataFu||DataFu provides a collection of Hadoop MapReduce jobs and functions in higher level languages based on it to perform data analysis. It provides functions for common statistics tasks (e.g. quantiles, sampling), PageRank, stream sessionization, and set and bag operations. DataFu also provides Hadoop jobs for incremental data processing in MapReduce. DataFu is a collection of Pig UDFs (including PageRank, sessionization, set operations, sampling, and much more) that were originally developed at LinkedIn.||1. DataFu Apache Incubator|
|Pydoop||Pydoop is a Python MapReduce and HDFS API for Hadoop, built upon the C++ Pipes and the C libhdfs APIs, that allows to write full-fledged MapReduce applications with HDFS access. Pydoop has several advantages over Hadoop’s built-in solutions for Python programming, i.e., Hadoop Streaming and Jython: being a CPython package, it allows you to access all standard library and third party modules, some of which may not be available.||1. SF Pydoop site
2. Pydoop GitHub Project
|Kangaroo||Open-source project from Conductor for writing MapReduce jobs consuming data from Kafka. The introductory post explains Conductor’s use case—loading data from Kafka to HBase by way of a MapReduce job using the HFileOutputFormat. Unlike other solutions which are limited to a single InputSplit per Kafka partition, Kangaroo can launch multiple consumers at different offsets in the stream of a single partition for increased throughput and parallelism.||1. Kangaroo Introduction
2. Kangaroo GitHub Project