Sorry for the repeat email. I am having technical difficulties. This
attachment should be correct.
----- Original Message -----
From: "Baum, Karl" <[EMAIL PROTECTED]>
To: "Turbine JCS Developers List" <[EMAIL PROTECTED]>
Sent: Sunday, June 15, 2003 10:22 PM
Subject: TCP Lateral Caching bug fix
> I noticed a problem with lateral caching when configuring two or more
> TCP servers. The problem has to do with lateral cache recovery process
> when losing connections. I have attached a fix.
>
>
>
>
>
> Main Issue:
>
>
>
> I have three lateral cache servers. I start one server first. Because
> the other lateral TCP servers are not yet running, the first server
> fails to connect to the others and begins recovery mode. In recovery
> mode, a LateralCacheMonitor thread runs every 20 seconds trying to
> create connections to the other servers. I noticed the thread was only
> trying to create a connection to one of the other cache servers. The
> result was that when I brought the other two servers up, the initial
> server only successfully connected to one out of the other two servers.
> This was always the last of the TCP servers in the comma separated list.
>
>
>
> Cause:
>
>
>
> The problem is caused by the reuse of the same LateralCacheAttributes
> object. For each of the TCP servers, a LateralCacheManager is created.
> Each LateralCacheManager is created with an instance of
> LateraCacheAttributes. Before instantiating the LateralCacheManager,
> the specific TCP server is set on the LateralCacheAttributes object.
> Since the same instance of LateralCacheAttributes is used each time, the
> call to set the TCP server overwrites the previous TCP server each time.
> In recovery mode, the TCP server property on the LateralCacheAttributes
> is used to reestablish the connections. Recovery mode will always
> attempt to reestablish a connection to the last of the TCP servers since
> this was the last server to be set in the LateralCacheAttributes object.
>
>
>
> Fix:
>
>
>
> To fix this issue, I modified the class LateralCacheFactory. Now
> LateralCacheFactory calls set TCP server on a clone of the
> LateralCacheAttributes object. As a result, the previous TCP server is
> not overwritten.
>
>
>
> CVS diff:
>
>
>
> $ cvs -d :pserver:[EMAIL PROTECTED]:/home/cvspublic diff -u
> LateralCacheFactory.java
>
> Index: LateralCacheFactory.java
>
> ===================================================================
>
> RCS file:
> /home/cvspublic/jakarta-turbine-jcs/src/java/org/apache/jcs/auxiliary/la
> teral/LateralCacheFactory.java,v
>
> retrieving revision 1.4
>
> diff -u -r1.4 LateralCacheFactory.java
>
> --- LateralCacheFactory.java 7 Aug 2002 15:28:12 -0000 1.4
>
> +++ LateralCacheFactory.java 16 Jun 2003 02:14:43 -0000
>
> @@ -73,15 +73,16 @@
>
> StringTokenizer it = new StringTokenizer( lac.tcpServers,
> "," );
>
> while ( it.hasMoreElements() )
>
> {
>
> + LateralCacheAttributes lacClone =
> (LateralCacheAttributes)lac.copy();
>
> //String server = (String)it.next();
>
> String server = ( String ) it.nextElement();
>
> if ( log.isDebugEnabled() )
>
> {
>
> log.debug( "tcp server = " + server );
>
> }
>
> - lac.setTcpServer( server );
>
> - LateralCacheManager lcm =
> LateralCacheManager.getInstance( lac );
>
> - ICache ic = lcm.getCache( lac.getCacheName() );
>
> + lacClone.setTcpServer( server );
>
> + LateralCacheManager lcm =
> LateralCacheManager.getInstance( lacClone );
>
> + ICache ic = lcm.getCache( lacClone.getCacheName() );
>
> if ( ic != null )
>
> {
>
> noWaits.add( ic );
>
>
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