##### 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 0.19.1 - 2009-02-24

### INCOMPATIBLE CHANGES:

JIRA | Summary | Priority | Component | Reporter | Contributor
--- | --- | --- | --- | --- | ---
HADOOP-4061 | Large number of decommission freezes the Namenode | Major | . | Koji Noguchi | Tsz Wo Nicholas Sze
HADOOP-5225 | workaround for tmp file handling on DataNodes in 0.19.1 (HADOOP-4663) | Blocker | . | Nigel Daley | Raghu Angadi
HADOOP-5224 | Disable append | Blocker | . | Nigel Daley |

### NEW FEATURES:

JIRA | Summary | Priority | Component | Reporter | Contributor
--- | --- | --- | --- | --- | ---
HADOOP-5034 | NameNode should send both replication and deletion requests to DataNode in one reply to a heartbeat | Major | . | Hairong Kuang | Hairong Kuang

### IMPROVEMENTS:

JIRA | Summary | Priority | Component | Reporter | Contributor
--- | --- | --- | --- | --- | ---
HADOOP-4739 | Minor enhancements to some sections of the Map/Reduce tutorial | Trivial | . | Vivek Ratan | Vivek Ratan
HADOOP-3894 | DFSClient chould log errors better, and provide better diagnostics | Trivial | . | Steve Loughran | Steve Loughran
HADOOP-5086 | Trash URI semantics can be relaxed | Minor | fs | Chris Douglas | Chris Douglas
HADOOP-5127 | FSDirectory should not have public methods. | Major | . | Konstantin Shvachko | Jakob Homan

### BUG FIXES:

JIRA | Summary | Priority | Component | Reporter | Contributor
--- | --- | --- | --- | --- | ---
HADOOP-4616 | assertion makes fuse-dfs exit when reading incomplete data | Blocker | . | Marc-Olivier Fleury | Pete Wyckoff
HADOOP-4697 | KFS::getBlockLocations() fails with files having multiple blocks | Major | fs | Lohit Vijayarenu | Sriram Rao
HADOOP-4720 | docs/api does not contain the hdfs directory after building | Major | build | Ramya Sunil |
HADOOP-4635 | Memory leak ? | Blocker | . | Marc-Olivier Fleury | Pete Wyckoff
HADOOP-4420 | JobTracker.killJob() doesn’t check for the JobID being valid | Minor | . | Steve Loughran | Aaron Kimball
HADOOP-4632 | TestJobHistoryVersion should not create directory in current dir. | Major | . | Amareshwari Sriramadasu | Amar Kamat
HADOOP-4508 | FSDataOutputStream.getPos() == 0when appending to existing file and should be file length | Major | fs | Pete Wyckoff | dhruba borthakur
HADOOP-4727 | Groups do not work for fuse-dfs out of the box on 0.19.0 | Blocker | . | Brian Bockelman | Brian Bockelman
HADOOP-4731 | Job is not removed from the waiting jobs queue upon completion. | Major | . | Hemanth Yamijala | Amar Kamat
HADOOP-4836 | Minor typos in documentation and comments | Trivial | documentation | Jordà Polo | Jordà Polo
HADOOP-4821 | Usage description in the Quotas guide documentations are incorrect | Minor | documentation | Boris Shkolnik | Boris Shkolnik
HADOOP-4797 | RPC Server can leave a lot of direct buffers | Blocker | ipc | Raghu Angadi | Raghu Angadi
HADOOP-4924 | Race condition in re-init of TaskTracker | Blocker | . | Devaraj Das | Devaraj Das
HADOOP-4847 | OutputCommitter is loaded in the TaskTracker in localizeConfiguration | Blocker | . | Owen O’Malley | Amareshwari Sriramadasu
HADOOP-4966 | Setup tasks are not removed from JobTracker’s taskIdToTIPMap even after the job completes | Major | . | Amar Kamat | Amareshwari Sriramadasu
HADOOP-4992 | TestCustomOutputCommitter fails on hadoop-0.19 | Blocker | . | Amar Kamat | Amareshwari Sriramadasu
HADOOP-4982 | TestFsck does not run in Eclipse. | Major | test | Konstantin Shvachko | Konstantin Shvachko
HADOOP-5008 | TestReplication#testPendingReplicationRetry leaves an opened fd unclosed | Major | test | Hairong Kuang | Hairong Kuang
HADOOP-4943 | fair share scheduler does not utilize all slots if the task trackers are configured heterogeneously | Major | . | Zheng Shao | Zheng Shao
HADOOP-4906 | TaskTracker running out of memory after running several tasks | Blocker | . | Arun C Murthy | Sharad Agarwal
HADOOP-4918 | Fix bzip2 work with SequenceFile | Major | io | Zheng Shao | Zheng Shao
HADOOP-4965 | DFSClient should log instead of printing into std err. | Major | test | Konstantin Shvachko | Konstantin Shvachko
HADOOP-4967 | Inconsistent state in JVM manager | Major | . | Amareshwari Sriramadasu | Devaraj Das
HADOOP-5002 | 2 core tests TestFileOutputFormat and TestHarFileSystem are failing in branch 19 | Blocker | . | Ravi Gummadi | Amareshwari Sriramadasu
HADOOP-4983 | Job counters sometimes go down as tasks run without task failures | Critical | . | Owen O’Malley | Amareshwari Sriramadasu
HADOOP-5009 | DataNode#shutdown sometimes leaves data block scanner verification log unclosed | Major | . | Hairong Kuang | Hairong Kuang
HADOOP-4955 | Make DBOutputFormat us column names from setOutput(…) | Major | . | Kevin Peterson | Kevin Peterson
HADOOP-4862 | A spurious IOException log on DataNode is not completely removed | Blocker | . | Raghu Angadi | Raghu Angadi
HADOOP-5156 | TestHeartbeatHandling uses MiniDFSCluster.getNamesystem() which does not exist in branch 0.20 | Major | test | Konstantin Shvachko | Hairong Kuang
HADOOP-4759 | HADOOP-4654 to be fixed for branches >= 0.19 | Major | . | Amareshwari Sriramadasu | Amareshwari Sriramadasu
HADOOP-5161 | Accepted sockets do not get placed in DataXceiverServer#childSockets | Major | . | Hairong Kuang | Hairong Kuang
HADOOP-5193 | SecondaryNameNode does not rollImage because of incorrect calculation of edits modification time. | Major | . | Konstantin Shvachko | Konstantin Shvachko
HADOOP-4494 | libhdfs does not call FileSystem.append when O_APPEND passed to hdfsOpenFile | Major | . | Pete Wyckoff | Pete Wyckoff
HADOOP-5166 | JobTracker fails to restart if recovery and ACLs are enabled | Blocker | . | Karam Singh | Amar Kamat
HADOOP-5192 | Block reciever should not remove a finalized block when block replication fails | Blocker | . | Hairong Kuang | Hairong Kuang
HADOOP-5067 | Failed/Killed attempts column in jobdetails.jsp does not show the number of failed/killed attempts correctly | Major | . | Amareshwari Sriramadasu | Amareshwari Sriramadasu
HADOOP-4760 | HDFS streams should not throw exceptions when closed twice | Major | fs, fs/s3 | Alejandro Abdelnur | Enis Soztutar
HADOOP-5134 | FSNamesystem#commitBlockSynchronization adds under-construction block locations to blocksMap | Blocker | . | Hairong Kuang | dhruba borthakur
HADOOP-5268 | Using MultipleOutputFormat and setting reducers to 0 causes org.apache.hadoop.hdfs.protocol.AlreadyBeingCreatedException and job to fail | Major | . | Thibaut |
HADOOP-5665 | Namenode could not be formatted because the “whoami” program could not be run. | Major | . | Evelyn Sylvia |