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https://issues.apache.org/jira/browse/HADOOP-17098?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17241688#comment-17241688
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Ahmed Hussein commented on HADOOP-17098:
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bq. What is the relationship between this JIRA and HADOOP-17288? I think with
the latter we can avoid most of the Guava issues no?
[~csun], I am sorry I haven't seen your comment.
Shading Guava in HADOOP-17288 solves the conflicts of Guava library in Hadoop
upstream, downstreams, and the other projects (hbase,etc..).
The Guava byte code will still be loaded and be part of the runtime.
This Jira (when complete) gets rid of the Guava byte code which has the
following benefits:
* reduce memory fooprint. (less classes to load)
* better code management: Guava will likely has security updates that forces
Hadoop to adopt new releases and dealing with compatibilities.
* avoid struggles analyzing guava performance
> Reduce Guava dependency in Hadoop source code
> ---------------------------------------------
>
> Key: HADOOP-17098
> URL: https://issues.apache.org/jira/browse/HADOOP-17098
> Project: Hadoop Common
> Issue Type: Task
> Reporter: Ahmed Hussein
> Assignee: Ahmed Hussein
> Priority: Major
>
> Relying on Guava implementation in Hadoop has been painful due to
> compatibility and vulnerability issues.
> Guava updates tend to break/deprecate APIs. This made It hard to maintain
> backward compatibility within hadoop versions and clients/downstreams.
> With 3.x uses java8+, the java 8 features should preferred to Guava, reducing
> the footprint, and giving stability to source code.
> This jira should serve as an umbrella toward an incremental effort to reduce
> the usage of Guava in the source code and to create subtasks to replace Guava
> classes with Java features.
> Furthermore, it will be good to add a rule in the pre-commit build to warn
> against introducing a new Guava usage in certain modules.
> Any one willing to take part in this code refactoring has to:
> # Focus on one module at a time in order to reduce the conflicts and the
> size of the patch. This will significantly help the reviewers.
> # Run all the unit tests related to the module being affected by the change.
> It is critical to verify that any change will not break the unit tests, or
> cause a stable test case to become flaky.
> # Merge should be done to the following branches: trunk, branch-3.3,
> branch-3.2, branch-3.1
>
> A list of sub tasks replacing Guava APIs with java8 features:
> {code:java}
> com.google.common.io.BaseEncoding#base64() java.util.Base64
> com.google.common.io.BaseEncoding#base64Url() java.util.Base64
> com.google.common.base.Joiner.on()
> java.lang.String#join() or
>
> java.util.stream.Collectors#joining()
> com.google.common.base.Optional#of() java.util.Optional#of()
> com.google.common.base.Optional#absent()
> java.util.Optional#empty()
> com.google.common.base.Optional#fromNullable()
> java.util.Optional#ofNullable()
> com.google.common.base.Optional
> java.util.Optional
> com.google.common.base.Predicate
> java.util.function.Predicate
> com.google.common.base.Function
> java.util.function.Function
> com.google.common.base.Supplier
> java.util.function.Supplier
> {code}
>
> I also vote for the replacement of {{Precondition}} with either a wrapper, or
> Apache commons lang.
> I believe you guys have dealt with Guava compatibilities in the past and
> probably have better insights. Any thoughts? [~weichiu], [~gabor.bota],
> [~ste...@apache.org], [~ayushtkn], [~busbey], [~jeagles], [~kihwal]
>
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