hadoop/hadoop-common-project/hadoop-common/src/site/markdown/release/3.3.5/RELEASENOTES.3.3.5.md

Apache Hadoop 3.3.5 Release Notes

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

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• HADOOP-17956 | Major | Replace all default Charset usage with UTF-8

All of the default charset usages have been replaced to UTF-8. If the default charset of your environment is not UTF-8, the behavior can be different.

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• HADOOP-15983 | Major | Use jersey-json that is built to use jackson2

Use modified jersey-json 1.20 in https://github.com/pjfanning/jersey-1.x/tree/v1.20 that uses Jackson 2.x. By this change, Jackson 1.x dependency has been removed from Hadoop. downstream applications which explicitly exclude jersey from transitive dependencies must now exclude com.github.pjfanning:jersey-json

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• HDFS-16595 | Major | Slow peer metrics - add median, mad and upper latency limits

Namenode metrics that represent Slownode Json now include three important factors (median, median absolute deviation, upper latency limit) that can help user determine how urgently a given slownode requires manual intervention.

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• HADOOP-17833 | Minor | Improve Magic Committer Performance

S3A filesytem's createFile() operation supports an option to disable all safety checks when creating a file. Consult the documentation and use with care

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• HADOOP-18382 | Minor | Upgrade AWS SDK to V2 - Prerequisites

In preparation for an (incompatible but necessary) move to the AWS SDK v2, some uses of internal/deprecated uses of AWS classes/interfaces are logged as warnings, though only once during the life of a JVM. Set the log "org.apache.hadoop.fs.s3a.SDKV2Upgrade" to only log at INFO to hide these.

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• HADOOP-18442 | Major | Remove the hadoop-openstack module

The swift:// connector for openstack support has been removed. It had fundamental problems (swift's handling of files > 4GB). A subset of the S3 protocol is now exported by almost all object store services -please use that through the s3a connector instead. The hadoop-openstack jar remains, only now it is empty of code. This is to ensure that projects which declare the JAR a dependency will still have successful builds.

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• HADOOP-17563 | Major | Update Bouncy Castle to 1.68 or later

bouncy castle 1.68+ is a multirelease JAR containing java classes compiled for different target JREs. older versions of asm.jar and maven shade plugin may have problems with these. fix: upgrade the dependencies

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• HADOOP-18528 | Major | Disable abfs prefetching by default

ABFS block prefetching has been disabled to avoid HADOOP-18521 and buffer sharing on multithreaded processes (Hive, Spark etc). This will have little/no performance impact on queries against Parquet or ORC data, but can slow down sequential stream processing, including CSV files -however, the read data will be correct. It may slow down distcp downloads, where the race condition does not arise. For maximum distcp performance re-enable the readahead by setting fs.abfs.enable.readahead to true.

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• HADOOP-18621 | Critical | CryptoOutputStream::close leak when encrypted zones + quota exceptions

WARNING: No release note provided for this change.