[jira] Commented: (DIRMINA-374) ArrayIndexOutOfBoundException in SocketAcceptor and SocketConnector

["Srikanth Veeramachaneni (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/DIRMINA-374?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12506188 ] 

Srikanth Veeramachaneni commented on DIRMINA-374:
-------------------------------------------------

This might be very trivial, but I don't believe that the fix works when processorCount is greater than 1. It doesn't ensure proper distribution and actually generates a negative index when processorCount is greater than 2.

 - The first problem is that the check for negative is being done after the increment in "if ( processorDistributor++ < 0 )".
 - The second problem is that the index restarts from 0 irrespective of the previous index value which doesn't ensure proper distribution (this is very trivial, but we might as well fix it while addressing the first issue).

Here is a patch which I believe will address the issue the correct way.

Index: trunk/core/src/main/java/org/apache/mina/transport/socket/nio/SocketAcceptor.java
===================================================================
--- trunk/core/src/main/java/org/apache/mina/transport/socket/nio/SocketAcceptor.java   (revision 548724)
+++ trunk/core/src/main/java/org/apache/mina/transport/socket/nio/SocketAcceptor.java   (working copy)
@@ -427,12 +427,12 @@
 
     private SocketIoProcessor nextProcessor()
     {
-        if ( processorDistributor++ < 0 ) 
-        { 
-            processorDistributor = 0; 
-        } 
+        if ( this.processorDistributor == Integer.MAX_VALUE )
+        {
+            this.processorDistributor = Integer.MAX_VALUE % this.processorCount;
+        }
 
-        return ioProcessors[processorDistributor % processorCount];
+        return ioProcessors[processorDistributor++ % processorCount];
     }
 
     private void registerNew()


> ArrayIndexOutOfBoundException in SocketAcceptor and SocketConnector
> -------------------------------------------------------------------
>
>                 Key: DIRMINA-374
>                 URL: https://issues.apache.org/jira/browse/DIRMINA-374
>             Project: MINA
>          Issue Type: Bug
>          Components: Core
>    Affects Versions: 1.0.0, 1.0.1, 1.0.2, 1.0.3, 1.1.0
>            Reporter: Trustin Lee
>            Priority: Critical
>             Fix For: 1.0.4, 1.1.1, 2.0.0-M1
>
>
> From Mladen Turk <mt...@apache.org>:
> Hi,
> Here is the patch that fixes the SocketAcceptor.nextProcessor()
> The problem is that round robin distributor is integer and
> if you set the number of processors to > 1, after MAX_INTEGER
> requests (yes I know I tested that many :) it starts throwing
> something like:
> java.lang.ArrayIndexOutOfBoundsException: -3
> The reason?
> -value % 1 is always 0|1
> -value % 2 is always 0|-1
> Anyhow, enough math, here is the patch.
> Regards,
> Mladen.
> Index: SocketAcceptor.java
> ===================================================================
> --- SocketAcceptor.java (revision 533579)
> +++ SocketAcceptor.java (working copy)
> @@ -422,7 +422,11 @@
>     private SocketIoProcessor nextProcessor()
>     {
> -        return ioProcessors[processorDistributor++ % processorCount];
> +        if ( processorDistributor++ < 0 )
> +        {
> +            processorDistributor = 0;
> +        }
> +        return ioProcessors[processorDistributor % processorCount];
>     }
>     private void registerNew()

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