##### 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 0.20.2 - 2010-02-16

### INCOMPATIBLE CHANGES:

JIRA | Summary | Priority | Component | Reporter | Contributor
--- | --- | --- | --- | --- | ---
HDFS-793 | DataNode should first receive the whole packet ack message before it constructs and sends its own ack message for the packet | Blocker | datanode | Hairong Kuang | Hairong Kuang

### IMPROVEMENTS:

JIRA | Summary | Priority | Component | Reporter | Contributor
--- | --- | --- | --- | --- | ---
MAPREDUCE-623 | Resolve javac warnings in mapred | Major | build | Jothi Padmanabhan | Jothi Padmanabhan
HADOOP-1849 | IPC server max queue size should be configurable | Major | ipc | Raghu Angadi | Konstantin Shvachko

### BUG FIXES:

JIRA | Summary | Priority | Component | Reporter | Contributor
--- | --- | --- | --- | --- | ---
HADOOP-5759 | IllegalArgumentException when CombineFileInputFormat is used as job InputFormat | Major | . | Amareshwari Sriramadasu | Amareshwari Sriramadasu
MAPREDUCE-826 | harchive doesn’t use ToolRunner / harchive returns 0 even if the job fails with exception | Trivial | harchive | Koji Noguchi | Koji Noguchi
MAPREDUCE-112 | Reduce Input Records and Reduce Output Records counters are not being set when using the new Mapreduce reducer API | Blocker | . | Jothi Padmanabhan | Jothi Padmanabhan
HADOOP-6231 | Allow caching of filesystem instances to be disabled on a per-instance basis | Major | fs | Tom White | Ben Slusky
MAPREDUCE-979 | JobConf.getMemoryFor{Map|Reduce}Task doesn’t fallback to newer config knobs when mapred.taskmaxvmem is set to DISABLED_MEMORY_LIMIT of -1 | Blocker | jobtracker, tasktracker | Arun C Murthy | Sreekanth Ramakrishnan
HDFS-677 | Rename failure due to quota results in deletion of src directory | Blocker | namenode | Suresh Srinivas | Suresh Srinivas
HDFS-579 | HADOOP-3792 update of DfsTask incomplete | Major | hdfs-client | Christian Kunz | Christian Kunz
MAPREDUCE-1070 | Deadlock in FairSchedulerServlet | Major | . | Todd Lipcon | Todd Lipcon
HADOOP-6097 | Multiple bugs w/ Hadoop archives | Major | fs | Ben Slusky | Ben Slusky
HDFS-723 | Deadlock in DFSClient#DFSOutputStream | Blocker | . | Hairong Kuang | Hairong Kuang
HDFS-732 | HDFS files are ending up truncated | Blocker | hdfs-client | Christian Kunz | Tsz Wo Nicholas Sze
MAPREDUCE-1163 | hdfsJniHelper.h: Yahoo! specific paths are encoded | Trivial | . | Allen Wittenauer | Allen Wittenauer
HDFS-761 | Failure to process rename operation from edits log due to quota verification | Major | namenode | Suresh Srinivas | Suresh Srinivas
MAPREDUCE-1068 | In hadoop-0.20.0 streaming job do not throw proper verbose error message if file is not present | Major | contrib/streaming | Peeyush Bishnoi | Amareshwari Sriramadasu
HDFS-596 | Memory leak in libhdfs: hdfsFreeFileInfo() in libhdfs does not free memory for mOwner and mGroup | Blocker | fuse-dfs | Zhang Bingjun | Zhang Bingjun
MAPREDUCE-1147 | Map output records counter missing for map-only jobs in new API | Blocker | . | Chris Douglas | Amar Kamat
HADOOP-6269 | Missing synchronization for defaultResources in Configuration.addResource | Major | conf | Todd Lipcon | Sreekanth Ramakrishnan
MAPREDUCE-1182 | Reducers fail with OutOfMemoryError while copying Map outputs | Blocker | . | Chandra Prakash Bhagtani | Chandra Prakash Bhagtani
HDFS-781 | Metrics PendingDeletionBlocks is not decremented | Blocker | namenode | Suresh Srinivas | Suresh Srinivas
HDFS-185 | Chown , chgrp , chmod operations allowed when namenode is in safemode . | Major | . | Ravi Phulari | Ravi Phulari
HADOOP-6428 | HttpServer sleeps with negative values | Major | . | Tsz Wo Nicholas Sze | Konstantin Boudnik
HDFS-101 | DFS write pipeline : DFSClient sometimes does not detect second datanode failure | Blocker | datanode | Raghu Angadi | Hairong Kuang
HADOOP-6460 | Namenode runs of out of memory due to memory leak in ipc Server | Blocker | . | Suresh Srinivas | Suresh Srinivas
HADOOP-5623 | Streaming: process provided status messages are overwritten every 10 seoncds | Major | . | Rick Cox | Rick Cox
HADOOP-6315 | GzipCodec should not represent BuiltInZlibInflater as decompressorType | Major | io | Aaron Kimball | Aaron Kimball
HDFS-187 | TestStartup fails if hdfs is running in the same machine | Major | test | Tsz Wo Nicholas Sze | Todd Lipcon
HDFS-745 | TestFsck timeout on 0.20. | Major | . | Tsz Wo Nicholas Sze | Tsz Wo Nicholas Sze
MAPREDUCE-433 | TestReduceFetch failed. | Major | . | Tsz Wo Nicholas Sze | Chris Douglas
HADOOP-6498 | IPC client bug may cause rpc call hang | Blocker | ipc | Ruyue Ma | Ruyue Ma
HDFS-872 | DFSClient 0.20.1 is incompatible with HDFS 0.20.2 | Major | datanode, hdfs-client | Bassam Tabbara | Todd Lipcon
MAPREDUCE-1010 | Adding tests for changes in archives. | Minor | harchive | Mahadev konar | Mahadev konar
HADOOP-6506 | Failing tests prevent the rest of test targets from execution. | Major | build | Konstantin Boudnik | Konstantin Boudnik
HADOOP-6524 | Contrib tests are failing Clover’ed build | Major | build | Konstantin Boudnik | Konstantin Boudnik
HDFS-927 | DFSInputStream retries too many times for new block locations | Critical | hdfs-client | Todd Lipcon | Todd Lipcon
HADOOP-5611 | C++ libraries do not build on Debian Lenny | Critical | . | Todd Lipcon | Todd Lipcon
MAPREDUCE-1251 | c++ utils doesn’t compile | Major | . | Eli Collins | Eli Collins
HADOOP-5612 | Some c++ scripts are not chmodded before ant execution | Major | build | Todd Lipcon | Todd Lipcon
HADOOP-6575 | Tests do not run on 0.20 branch | Major | . | Chris Douglas | Chris Douglas
HADOOP-6576 | TestStreamingStatus is failing on 0.20 branch | Major | . | Chris Douglas | Todd Lipcon
MAPREDUCE-617 | Streaming should not throw java.lang.RuntimeException and ERROR while displaying help | Minor | contrib/streaming | Karam Singh |

### TESTS:

JIRA | Summary | Priority | Component | Reporter | Contributor
--- | --- | --- | --- | --- | ---
HDFS-919 | Create test to validate the BlocksVerified metric | Major | test | gary murry |
HDFS-907 | Add tests for getBlockLocations and totalLoad metrics. | Minor | namenode | Ravi Phulari | Ravi Phulari