[jboss-jira] [JBoss JIRA] (JGRP-1871) NPEs due to non-volatile Protocol variables

[Paul Ferraro (JIRA)]

    [ https://issues.jboss.org/browse/JGRP-1871?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12992455#comment-12992455 ] 

Paul Ferraro commented on JGRP-1871:
------------------------------------

That said, it may be worth addressing this anyway.  It one were to make runtime modifications to a given protocol property, unless that property is volatile, or some other memory synchronization is in place, its visibility to other threads is not guaranteed by the java memory model.

> NPEs due to non-volatile Protocol variables
> -------------------------------------------
>
>                 Key: JGRP-1871
>                 URL: https://issues.jboss.org/browse/JGRP-1871
>             Project: JGroups
>          Issue Type: Bug
>      Security Level: Public(Everyone can see) 
>    Affects Versions: 3.4.5, 3.5
>            Reporter: Paul Ferraro
>            Assignee: Paul Ferraro
>
> In WildFly a given channel is created in one thread, but is potentially started in a different thread.  Unfortunately, many of the protocol variables that are set during Protocol.init() are non-volatile. This can cause unexpected behavior as seen in WFLY-3727.
> To ensure clean initialization for multi-threaded environments like WF, all non-final variables within every JGroups' Protocol should be volatile.



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