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From "Daryn Sharp (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HADOOP-16282) Avoid FileStream to improve performance
Date Fri, 03 May 2019 17:51:00 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-16282?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16832694#comment-16832694

Daryn Sharp commented on HADOOP-16282:

Please consider reverting most or all of this patch.

I know finalized object are "bad" but this seemingly simple change is high risk according
to the linked java bug:
{quote}The unresolvable compatibility issue is the requirement in FileInputStream and FileOutputStream
finalizer methods to call close. ... Since it is unknown/unknowable how many FIS/FOS subclasses
might rely on overriding close or finalize +_*the compatibility issue is severe*_+.  +Only
a long term (multiple release) restriction to deprecate or invalidate overriding would have
possibility of eventually eliminating the compatibility problem.+ 

As best I can tell, leak a NIO stream and forever leak the file descriptor.  The exceptions
are completely different so anyone expecting to catch {{FileNotFoundException}}, ie. at least
from {{FileUtil}}, are going to be surprised that it's now {{NoSuchFileException}}.

And please do not span components if at all possible.  There is a hdfs project for hdfs bugs.

> Avoid FileStream to improve performance
> ---------------------------------------
>                 Key: HADOOP-16282
>                 URL: https://issues.apache.org/jira/browse/HADOOP-16282
>             Project: Hadoop Common
>          Issue Type: Improvement
>            Reporter: Ayush Saxena
>            Assignee: Ayush Saxena
>            Priority: Major
>             Fix For: 3.3.0
>         Attachments: HADOOP-16282-01.patch, HADOOP-16282-02.patch
> The FileInputStream and FileOutputStream classes contains a finalizer method which will
cause garbage collection pauses. See [JDK-8080225|https://bugs.openjdk.java.net/browse/JDK-8080225]
for details.
> The FileReader and FileWriter constructors instantiate FileInputStream and FileOutputStream,
again causing garbage collection issues while finalizer methods are called.

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