##### General

- Overview
- Single Node Setup
- Cluster Setup
- Commands Reference
- FileSystem Shell
- Compatibility Specification
- Downstream Developer's Guide
- Admin Compatibility Guide
- Interface Classification
- FileSystem Specification

##### Common

- CLI Mini Cluster
- Native Libraries
- Proxy User
- Rack Awareness
- Secure Mode
- Service Level Authorization
- HTTP Authentication
- Credential Provider API
- Hadoop KMS
- Tracing
- Unix Shell Guide

##### HDFS

- Architecture
- User Guide
- Commands Reference
- NameNode HA With QJM
- NameNode HA With NFS
- Observer NameNode
- Federation
- ViewFs
- ViewFsOverloadScheme
- Snapshots
- Edits Viewer
- Image Viewer
- Permissions and HDFS
- Quotas and HDFS
- libhdfs (C API)
- WebHDFS (REST API)
- HttpFS
- Short Circuit Local Reads
- Centralized Cache Management
- NFS Gateway
- Rolling Upgrade
- Extended Attributes
- Transparent Encryption
- Multihoming
- Storage Policies
- Memory Storage Support
- Synthetic Load Generator
- Erasure Coding
- Disk Balancer
- Upgrade Domain
- DataNode Admin
- Router Federation
- Provided Storage

##### MapReduce

- Tutorial
- Commands Reference
- Compatibility with 1.x
- Encrypted Shuffle
- Pluggable Shuffle/Sort
- Distributed Cache Deploy
- Support for YARN Shared Cache

##### MapReduce REST APIs

- MR Application Master
- MR History Server

##### YARN

- Architecture
- Commands Reference
- Capacity Scheduler
- Fair Scheduler
- ResourceManager Restart
- ResourceManager HA
- Resource Model
- Node Labels
- Node Attributes
- Web Application Proxy
- Timeline Server
- Timeline Service V.2
- Writing YARN Applications
- YARN Application Security
- NodeManager
- Running Applications in Docker Containers
- Using CGroups
- Secure Containers
- Registry
- Reservation System
- Graceful Decommission
- Opportunistic Containers
- YARN Federation
- Shared Cache
- Using GPU
- Using FPGA
- Placement Constraints
- YARN UI2

##### YARN REST APIs

- Introduction
- Resource Manager
- Node Manager
- Timeline Server
- Timeline Service V.2

##### YARN Service

- Overview
- QuickStart
- Concepts
- Yarn Service API
- Service Discovery
- System Services

##### Submarine

- Index
- QuickStart
- Examples

##### Hadoop Compatible File Systems

- Aliyun OSS
- Amazon S3
- Azure Blob Storage
- Azure Data Lake Storage
- OpenStack Swift

##### Auth

- Overview
- Examples
- Configuration
- Building

##### Tools

- Hadoop Streaming
- Hadoop Archives
- Hadoop Archive Logs
- DistCp
- GridMix
- Rumen
- Resource Estimator Service
- Scheduler Load Simulator
- Hadoop Benchmarking

##### Reference

- Changelog and Release Notes
- Java API docs
- Unix Shell API
- Metrics

##### Configuration

- core-default.xml
- hdfs-default.xml
- hdfs-rbf-default.xml
- mapred-default.xml
- yarn-default.xml
- kms-default.xml
- httpfs-default.xml
- Deprecated Properties

# Apache Hadoop Changelog

## Release 0.20.3 - Unreleased (as of 2018-09-01)

### INCOMPATIBLE CHANGES:

JIRA | Summary | Priority | Component | Reporter | Contributor
--- | --- | --- | --- | --- | ---
HADOOP-6382 | publish hadoop jars to apache mvn repo. | Major | build | Giridharan Kesavan | Giridharan Kesavan
HDFS-132 | Namenode in Safemode reports to Simon non-zero number of deleted files during startup | Minor | namenode | Hairong Kuang | Suresh Srinivas
HADOOP-6701 | Incorrect exit codes for “dfs -chown”, “dfs -chgrp” | Minor | fs | Ravi Phulari | Ravi Phulari

### IMPROVEMENTS:

JIRA | Summary | Priority | Component | Reporter | Contributor
--- | --- | --- | --- | --- | ---
MAPREDUCE-1832 | Support for file sizes less than 1MB in DFSIO benchmark. | Major | benchmarks | Konstantin Shvachko | Konstantin Shvachko
HADOOP-7240 | Update eclipse .classpath template | Major | . | Aaron T. Myers | Aaron T. Myers
MAPREDUCE-1734 | Un-deprecate the old MapReduce API in the 0.20 branch | Blocker | documentation | Tom White | Todd Lipcon
HDFS-1013 | Miscellaneous improvements to HTML markup for web UIs | Minor | . | Todd Lipcon | Eugene Koontz
HADOOP-6882 | Update the patch level of Jetty | Major | . | Owen O’Malley | Owen O’Malley

### BUG FIXES:

JIRA | Summary | Priority | Component | Reporter | Contributor
--- | --- | --- | --- | --- | ---
HDFS-15 | Rack replication policy can be violated for over replicated blocks | Critical | . | Hairong Kuang | Jitendra Nath Pandey
MAPREDUCE-1522 | FileInputFormat may change the file system of an input path | Blocker | . | Tsz Wo Nicholas Sze | Tsz Wo Nicholas Sze
MAPREDUCE-1407 | Invalid example in the documentation of org.apache.hadoop.mapreduce.{Mapper,Reducer} | Trivial | documentation | Benoit Sigoure | Benoit Sigoure
HDFS-955 | FSImage.saveFSImage can lose edits | Blocker | namenode | Todd Lipcon | Konstantin Shvachko
HDFS-1041 | DFSClient does not retry in getFileChecksum(..) | Major | hdfs-client | Tsz Wo Nicholas Sze | Tsz Wo Nicholas Sze
HDFS-909 | Race condition between rollEditLog or rollFSImage ant FSEditsLog.write operations corrupts edits log | Blocker | namenode | Cosmin Lehene | Todd Lipcon
HADOOP-6702 | Incorrect exit codes for “dfs -chown”, “dfs -chgrp” when input is given in wildcard format. | Minor | fs | Ravi Phulari | Ravi Phulari
HADOOP-6760 | WebServer shouldn’t increase port number in case of negative port setting caused by Jetty’s race | Major | . | Konstantin Boudnik | Konstantin Boudnik
MAPREDUCE-1372 | ConcurrentModificationException in JobInProgress | Blocker | jobtracker | Amareshwari Sriramadasu | Dick King
MAPREDUCE-118 | Job.getJobID() will always return null | Blocker | client | Amar Kamat | Amareshwari Sriramadasu
MAPREDUCE-1880 | “java.lang.ArithmeticException: Non-terminating decimal expansion; no exact representable decimal result.” while running “hadoop jar hadoop-0.20.1+169.89-examples.jar pi 4 30” | Minor | examples | Victor Pakhomov | Tsz Wo Nicholas Sze
HDFS-1258 | Clearing namespace quota on “/” corrupts FS image | Blocker | namenode | Aaron T. Myers | Aaron T. Myers
HADOOP-6881 | The efficient comparators aren’t always used except for BytesWritable and Text | Major | . | Owen O’Malley | Owen O’Malley
HADOOP-6833 | IPC leaks call parameters when exceptions thrown | Blocker | . | Todd Lipcon | Todd Lipcon
HADOOP-6928 | Fix BooleanWritable comparator in 0.20 | Major | io | Owen O’Malley | Johannes Zillmann
HDFS-1404 | TestNodeCount logic incorrect in branch-0.20 | Minor | namenode, test | Todd Lipcon | Todd Lipcon
MAPREDUCE-1280 | Eclipse Plugin does not work with Eclipse Ganymede (3.4) | Major | . | Aaron Kimball | Alex Kozlov
HADOOP-6724 | IPC doesn’t properly handle IOEs thrown by socket factory | Major | ipc | Todd Lipcon | Todd Lipcon
HDFS-1240 | TestDFSShell failing in branch-20 | Critical | test | Todd Lipcon | Todd Lipcon
HDFS-727 | bug setting block size hdfsOpenFile | Blocker | libhdfs | Eli Collins | Eli Collins
HDFS-908 | TestDistributedFileSystem fails with Wrong FS on weird hosts | Minor | test | Todd Lipcon | Todd Lipcon
HDFS-1377 | Quota bug for partial blocks allows quotas to be violated | Blocker | namenode | Eli Collins | Eli Collins
HDFS-1406 | TestCLI fails on Ubuntu with default /etc/hosts | Minor | . | Todd Lipcon | Konstantin Boudnik
MAPREDUCE-2262 | Capacity Scheduler unit tests fail with class not found | Major | capacity-sched | Owen O’Malley | Owen O’Malley
HADOOP-6923 | Native Libraries do not load if a different platform signature is returned from org.apache.hadoop.util.PlatformName | Major | native | Stephen Watt | Stephen Watt
HDFS-1543 | Reduce dev. cycle time by moving system testing artifacts from default build and push to maven for HDFS | Major | . | Arun C Murthy | Luke Lu
HDFS-1836 | Thousand of CLOSE_WAIT socket | Major | hdfs-client | Dennis Cheung | Bharath Mundlapudi
HADOOP-7116 | raise contrib junit test jvm memory size to 512mb | Major | test | Owen O’Malley | Owen O’Malley

### TESTS:

JIRA | Summary | Priority | Component | Reporter | Contributor
--- | --- | --- | --- | --- | ---
HADOOP-6637 | Benchmark overhead of RPC session establishment | Major | benchmarks | Konstantin Shvachko | Konstantin Shvachko

### OTHER:

JIRA | Summary | Priority | Component | Reporter | Contributor
--- | --- | --- | --- | --- | ---
HDFS-1286 | Dry entropy pool on Hudson boxes causing test timeouts | Major | test | Todd Lipcon | Konstantin Boudnik
HADOOP-7372 | Remove ref of 20.3 release from branch-0.20 CHANGES.txt | Major | documentation | Eli Collins | Eli Collins