[jboss-jira] [JBoss JIRA] (JGRP-2355) TCP_NIO2 fails under Java 8

[Bela Ban (Jira)]

    [ https://issues.jboss.org/browse/JGRP-2355?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13749540#comment-13749540 ] 

Bela Ban commented on JGRP-2355:
--------------------------------

Hi Paul
why is this a blocker? First, we're not using TCP_NIO2 by default and secondly, people can build their own JAR using JDK 8.


> TCP_NIO2 fails under Java 8
> ---------------------------
>
>                 Key: JGRP-2355
>                 URL: https://issues.jboss.org/browse/JGRP-2355
>             Project: JGroups
>          Issue Type: Bug
>    Affects Versions: 4.1.1
>            Reporter: Paul Ferraro
>            Assignee: Bela Ban
>            Priority: Blocker
>             Fix For: 4.1.2
>
>
> Because the 4.1.x releases are built with JDK11, I see the following at runtime when running under Java 8:
> {noformat}
> WARN  [org.jgroups.protocols.TCP_NIO2] (TQ-Bundler-6,ejb,node-1) node-1: failed sending message to 127.0.0.1:7700: java.lang.NoSuchMethodError: java.nio.ByteBuffer.clear()Ljava/nio/ByteBuffer;
> {noformat}
> The problematic code seems to be here:
> https://github.com/belaban/JGroups/blob/master/src/org/jgroups/blocks/cs/NioConnection.java#L398
> In JDK8, Buffer.clear() was final and returned a Buffer object (hence the need for your code to cast).  However, in JDK11 Buffer.clear() is no longer final, allowing subclasses to override the return type, which ByteBuffer indeed does (to return a ByteBuffer).  However, since JGroups 4.1.x is built with JDK11, when running on Java 8, the method is not found.
> There are 2 ways to fix this:
> 1. Ensure 4.1.x releases are built using JDK8 (since source is still compatible with Java 8)
> 2. Cast java.io.ByteBuffer to java.nio.Buffer when invoking clear() to avoid the NoSuchMethodError.



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