Apache Hadoop 3.5.0 – Apache Hadoop 2.7.6 Release Notes

##### 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
- Fair Call Queue
- Native Libraries
- Proxy User
- Rack Awareness
- Secure Mode
- Service Level Authorization
- HTTP Authentication
- Credential Provider API
- Hadoop KMS
- Tracing
- Unix Shell Guide
- Registry
- Async Profiler

##### 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
- 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
- Running Applications in runC Containers
- Using CGroups
- Secure Containers
- 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

##### Hadoop Compatible File Systems

- Aliyun OSS
- Amazon S3
- Azure Blob Storage
- Azure Data Lake Storage
- Tencent COS
- Huaweicloud OBS
- VolcanoEngine TOS

##### Auth

- Overview
- Examples
- Configuration
- Building

##### Tools

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

##### 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 2.7.6 Release Notes

These release notes cover new developer and user-facing incompatibilities, important issues, features, and major improvements.

- HADOOP-9477 | Major | Add posixGroups support for LDAP groups mapping service

Add posixGroups support for LDAP groups mapping service. The change in LDAPGroupMapping is compatible with previous scenario. In LDAP, the group mapping between {{posixAccount}} and {{posixGroup}} is different from the general LDAPGroupMapping, one of the differences is the {{“memberUid”}} will be used to mapping {{posixAccount}} and {{posixGroup}}. The feature will handle the mapping in internal when configuration {{hadoop.security.group.mapping.ldap.search.filter.user}} is set as “posixAccount” and {{hadoop.security.group.mapping.ldap.search.filter.group}} is “posixGroup”.

- HADOOP-13105 | Major | Support timeouts in LDAP queries in LdapGroupsMapping.

This patch adds two new config keys for supporting timeouts in LDAP query operations. The property “hadoop.security.group.mapping.ldap.connection.timeout.ms” is the connection timeout (in milliseconds), within which period if the LDAP provider doesn’t establish a connection, it will abort the connect attempt. The property “hadoop.security.group.mapping.ldap.read.timeout.ms” is the read timeout (in milliseconds), within which period if the LDAP provider doesn’t get a LDAP response, it will abort the read attempt.

- HADOOP-13263 | Major | Reload cached groups in background after expiry

hadoop.security.groups.cache.background.reload can be set to true to enable background reload of expired groups cache entries. This setting can improve the performance of services that use Groups.java (e.g. the NameNode) when group lookups are slow. The setting is disabled by default.