##### 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 3.2.4 Release Notes

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

- YARN-10820 | Major | Make GetClusterNodesRequestPBImpl thread safe

Added syncronization so that the “yarn node list” command does not fail intermittently

- YARN-8234 | Critical | Improve RM system metrics publisher’s performance by pushing events to timeline server in batch

When Timeline Service V1 or V1.5 is used, if “yarn.resourcemanager.system-metrics-publisher.timeline-server-v1.enable-batch” is set to true, ResourceManager sends timeline events in batch. The default value is false. If this functionality is enabled, the maximum number that events published in batch is configured by “yarn.resourcemanager.system-metrics-publisher.timeline-server-v1.batch-size”. The default value is 1000. The interval of publishing events can be configured by “yarn.resourcemanager.system-metrics-publisher.timeline-server-v1.interval-seconds”. By default, it is set to 60 seconds.

- HADOOP-18088 | Major | Replace log4j 1.x with reload4j

log4j 1 was replaced with reload4j which is fork of log4j 1.2.17 with the goal of fixing pressing security issues.

If you are depending on the hadoop artifacts in your build were explicitly excluding log4 artifacts, and now want to exclude the reload4j files, you will need to update your exclusion lists <exclusion> <groupId>org.slf4j</groupId> <artifactId>slf4j-reload4j</artifactId> </exclusion> <exclusion> <groupId>ch.qos.reload4j</groupId> <artifactId>reload4j</artifactId> </exclusion>