![Fault Tolerance
• RDDs contain lineage.
• Lineage – source location and list of transformations
• Lost partitions can be re-computed from source data
23
msgs = textFile.filter(lambda s: s.startsWith(“ERROR”))
.map(lambda s: s.split(“t”)[2])
HDFS File Filtered RDD Mapped RDD
filter
(func = startsWith(…))
map
(func = split(...))](https://image.slidesharecdn.com/lvbigdatameetupdec3rd2014-141208125133-conversion-gate01/85/Apache-Spark-Las-Vegas-Big-Data-Meetup-Dec-3rd-2014-22-320.jpg)
![Word Count in MapReduce
package org.myorg;
import java.io.IOException;
import java.util.*;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.conf.*;
import org.apache.hadoop.io.*;
import org.apache.hadoop.mapreduce.*;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.input.TextInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat;
public class WordCount {
public static class Map extends Mapper<LongWritable, Text, Text, IntWritable> {
private final static IntWritable one = new IntWritable(1);
private Text word = new Text();
public void map(LongWritable key, Text value, Context context) throws IOException,
InterruptedException {
String line = value.toString();
StringTokenizer tokenizer = new StringTokenizer(line);
while (tokenizer.hasMoreTokens()) {
word.set(tokenizer.nextToken());
context.write(word, one);
}
}
}
25
public static class Reduce extends Reducer<Text, IntWritable, Text, IntWritable> {
public void reduce(Text key, Iterable<IntWritable> values, Context context)
throws IOException, InterruptedException {
int sum = 0;
for (IntWritable val : values) {
sum += val.get();
}
context.write(key, new IntWritable(sum));
}
}
public static void main(String[] args) throws Exception {
Configuration conf = new Configuration();
Job job = new Job(conf, "wordcount");
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(IntWritable.class);
job.setMapperClass(Map.class);
job.setReducerClass(Reduce.class);
job.setInputFormatClass(TextInputFormat.class);
job.setOutputFormatClass(TextOutputFormat.class);
FileInputFormat.addInputPath(job, new Path(args[0]));
FileOutputFormat.setOutputPath(job, new Path(args[1]));
job.waitForCompletion(true);
}
}](https://image.slidesharecdn.com/lvbigdatameetupdec3rd2014-141208125133-conversion-gate01/85/Apache-Spark-Las-Vegas-Big-Data-Meetup-Dec-3rd-2014-24-320.jpg)
Apache Spark - Las Vegas Big Data Meetup Dec 3rd 2014
- 1. CONFIDENTIAL - RESTRICTED Introduction to Spark LV Big Data Monthly Meetup #2 December 3rd 2014 Maxime Dumas Systems Engineer, Cloudera
- 2. Thirty Seconds About Max • Systems Engineer • aka Sales Engineer • SoCal, AZ, NV • former coder of PHP • teaches meditation + yoga • from Montreal, Canada 2
- 3. What Does Cloudera Do? • product • distribution of Hadoop components, Apache licensed • enterprise tooling • support • training • services (aka consulting) • community 3
- 4. 4 But first… how did we get here?
- 5. What does Hadoop look like? 5 HDFS HDFS … master worker (“NN”) (“DN”) MR worker (“TT”) HDFS worker (“DN”) MR worker (“TT”) HDFS worker (“DN”) MR worker (“TT”) HDFS worker (“DN”) MR worker (“TT”) HDFS worker (“DN”) MR worker (“TT”) MR master (“JT”) Standby master
- 6. But I want MORE! 6 HDFS worker HDFS worker HDFS worker HDFS worker HDFS worker … MapReduce HDFS master (“NN”) MR master (“JT”) Standby master
- 7. Hadoop as an Architecture The Old Way Network Expensive, Special purpose, “Reliable” Servers Expensive Licensed Software • Hard to scale • Network is a bottleneck • Only handles relational data • Difficult to add new fields & data types Expensive & Unattainable $30,000+ per TB Data Storage (SAN, NAS) Compute (RDBMS, EDW) The Hadoop Way Commodity “Unreliable” Servers Hybrid Open Source Software • Scales out forever • No bottlenecks • Easy to ingest any data • Agile data access Affordable & Attainable $300-$1,000 per TB Compute (CPU) Memory Storage (Disk) z z
- 8. CDH: the App Store for Hadoop 8 Resource Management Storage Integration Metadata NoSQL DBMS … Analytic MPP DBMS Search Engine In- Memory Batch Processing Support Data Management System Management Security Machine Learning MapReduce
- 9. 9 Introduction to Apache Spark Credits: • Ben White • Todd Lipcon • Ted Malaska • Jairam Ranganathan • Jayant Shekhar • Sandy Ryza
- 10. Can we improve on MR? • Problems with MR: • Very low-level: requires a lot of code to do simple things • Very constrained: everything must be described as “map” and “reduce”. Powerful but sometimes difficult to think in these terms. 10
- 11. Can we improve on MR? • Two approaches to improve on MapReduce: 1. Special purpose systems to solve one problem domain well. • Giraph / Graphlab (graph processing) • Storm (stream processing) • Impala (real-time SQL) 2. Generalize the capabilities of MapReduce to provide a richer foundation to solve problems. • Tez, MPI, Hama/Pregel (BSP), Dryad (arbitrary DAGs) Both are viable strategies depending on the problem! 11
- 12. What is Apache Spark? Spark is a general purpose computational framework Retains the advantages of MapReduce: • Linear scalability • Fault-tolerance • Data Locality based computations …but offers so much more: • Leverages distributed memory for better performance • Supports iterative algorithms that are not feasible in MR • Improved developer experience • Full Directed Graph expressions for data parallel computations • Comes with libraries for machine learning, graph analysis, etc. 12
- 13. What is Apache Spark? Run programs up to 100x faster than Hadoop MapReduce in memory, or 10x faster on disk. One of the largest open source projects in big data: • 170+ developers contributing • 30+ companies contributing • 400+ discussions per month on the mailing list 13
- 15. Getting started with Spark • Java API • Interactive shells: • Scala (spark-shell) • Python (pyspark) 15
- 17. Execution modes • Standalone Mode • Dedicated master and worker daemons • YARN Client Mode • Launches a YARN application with the driver program running locally • YARN Cluster Mode • Launches a YARN application with the driver program running in the YARN ApplicationMaster 17 Dedicated Spark runtime with static resource limits Dynamic resource management between Spark, MR, Impala…
- 19. RDD – Resilient Distributed Dataset • Collections of objects partitioned across a cluster • Stored in RAM or on Disk • You can control persistence and partitioning • Created by: • Distributing local collection objects • Transformation of data in storage • Transformation of RDDs • Automatically rebuilt on failure (resilient) • Contains lineage to compute from storage • Lazy materialization 20
- 21. Operations on RDDs Transformations lazily transform a RDD to a new RDD • map • flatMap • filter • sample • join • sort • reduceByKey • … Actions run computation to return a value • collect • reduce(func) • foreach(func) • count • first, take(n) • saveAs • … 22
- 22. Fault Tolerance • RDDs contain lineage. • Lineage – source location and list of transformations • Lost partitions can be re-computed from source data 23 msgs = textFile.filter(lambda s: s.startsWith(“ERROR”)) .map(lambda s: s.split(“t”)[2]) HDFS File Filtered RDD Mapped RDD filter (func = startsWith(…)) map (func = split(...))
- 23. 24 Examples
- 24. Word Count in MapReduce package org.myorg; import java.io.IOException; import java.util.*; import org.apache.hadoop.fs.Path; import org.apache.hadoop.conf.*; import org.apache.hadoop.io.*; import org.apache.hadoop.mapreduce.*; import org.apache.hadoop.mapreduce.lib.input.FileInputFormat; import org.apache.hadoop.mapreduce.lib.input.TextInputFormat; import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat; import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat; public class WordCount { public static class Map extends Mapper<LongWritable, Text, Text, IntWritable> { private final static IntWritable one = new IntWritable(1); private Text word = new Text(); public void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException { String line = value.toString(); StringTokenizer tokenizer = new StringTokenizer(line); while (tokenizer.hasMoreTokens()) { word.set(tokenizer.nextToken()); context.write(word, one); } } } 25 public static class Reduce extends Reducer<Text, IntWritable, Text, IntWritable> { public void reduce(Text key, Iterable<IntWritable> values, Context context) throws IOException, InterruptedException { int sum = 0; for (IntWritable val : values) { sum += val.get(); } context.write(key, new IntWritable(sum)); } } public static void main(String[] args) throws Exception { Configuration conf = new Configuration(); Job job = new Job(conf, "wordcount"); job.setOutputKeyClass(Text.class); job.setOutputValueClass(IntWritable.class); job.setMapperClass(Map.class); job.setReducerClass(Reduce.class); job.setInputFormatClass(TextInputFormat.class); job.setOutputFormatClass(TextOutputFormat.class); FileInputFormat.addInputPath(job, new Path(args[0])); FileOutputFormat.setOutputPath(job, new Path(args[1])); job.waitForCompletion(true); } }
- 25. Word Count in Spark sc.textFile(“words”) .flatMap(line => line.split(" ")) .map(word=>(word,1)) .reduceByKey(_+_).collect() 26
- 26. Logistic Regression • Read two sets of points • Looks for a plane W that separates them • Perform gradient descent: • Start with random W • On each iteration, sum a function of W over the data • Move W in a direction that improves it 27
- 27. Intuition 28
- 30. 31 Spark and Hadoop: a Framework within a Framework
- 31. 32
- 32. 33 Map Reduce Resource Management Storage Integration Metadata HBase Impala Solr Spark … Support Data Management System Management Security
- 33. Spark Streaming • Takes the concept of RDDs and extends it to DStreams • Fault-tolerant like RDDs • Transformable like RDDs • Adds new “rolling window” operations • Rolling averages, etc. • But keeps everything else! • Regular Spark code works in Spark Streaming • Can still access HDFS data, etc. • Example use cases: • “On-the-fly” ETL as data is ingested into Hadoop/HDFS. • Detecting anomalous behavior and triggering alerts. • Continuous reporting of summary metrics for incoming data. 34
- 34. Micro-batching for on the fly ETL 35
- 35. What about SQL? 36 http://databricks.com/blog/2014/07/01/shark-spark-sql-hive-on-spark-and-the-future-of-sql-on-spark.html http://blog.cloudera.com/blog/2014/07/apache-hive-on-apache-spark-motivations-and-design-principles/
- 36. Fault Recovery Recap • RDDs store dependency graph • Because RDDs are deterministic: Missing RDDs are rebuilt in parallel on other nodes • Stateful RDDs can have infinite lineage • Periodic checkpoints to disk clears lineage • Faster recovery times • Better handling of stragglers vs row-by-row streaming 37
- 37. Why Spark? • Flexible like MapReduce • High performance • Machine learning, iterative algorithms • Interactive data explorations • Concise, easy API for developer productivity 38
- 38. 39 Demo Time! • Log file Analysis • Machine Learning • Spark Streaming
- 39. What’s Next? • Download Hadoop! • CDH available at www.cloudera.com • Try it online: Cloudera Live • Cloudera provides pre-loaded VMs • http://tiny.cloudera.com/quickstartvm 40
- 40. 41 Questions? Preferably related to the talk… or not.
- 41. 42 Thank You! Maxime Dumas [email protected] We’re hiring.
- 42. 43
Editor's Notes
- #4: Similar to the Red Hat model. Hadoop elephant logo licensed for public use via Apache license: Apache Software Foundation, http://www.apache.org/foundation/marks/
- #6: What’s the best bang-per-buck you can get for computational capacity? Intel boxes running Linux! Sharded databases (and shared-nothing architectures like Teradata) look like this Let’s just get a ton of them, and figure out the rest with software (fault tolerance, distributed process management, job control, etc). And the rest is history - this is how Google, Facebook, Yahoo – this is how these guys build out their data centers.
- #7: So does this approach work for more than just MapReduce? Sure! You’ve got all this CPU and memory sitting here – let’s spin up more than just MapReduce. Let’s add an agent for a distributed SQL query engine, a distributed NoSQL database, distributed search…
- #8: Pricing Data: Cloudera: HW + SW per-year list prices for Basic thru EDH at various configs Old Way: Various sources. One of note: - Cowen / Goldmacher coverage initiation of Teradata, June 17, 2013 - List price of high-end appliance (which he thinks is more comparable to our solution) is $57K/TB + maintenance for an annual cost of $39K/TB - Prices have likely decreased, but we estimate they are still in excess of $30K/TB/year - List price of their low-end appliance is $12K/TB + maint or $8K per year