Good job, But a clear job for AOP in JB4. The cache product is DYNAMITE.
marcf > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On > Behalf Of Sacha Labourey > Sent: Sunday, November 23, 2003 6:17 PM > To: [EMAIL PROTECTED]; > [EMAIL PROTECTED] > Subject: [JBoss-dev] Tomcat session replication > > Hello, > > A few changes in the Tomcat HTTP Session replication code. > > First, some unnecessary synchronization has been removed. > This should lead to better scalability and in some cases > remove the impression that the replication is "hanging". > > Second, the replication has been improved. Without using > AOP-like frameworks, it is hard to determine when an HTTP > session is modified. When setAttribute is called, the > situation is (almost) obvious. However, if only getAttribute > is called, you never know as something like that could occur: > ( (HashMap)session.getAttribute ("bla") ).put > ("newKey", "newValue"); > > In that case, the setAttribute is never called but the > content of the session is modified. Consequently, it is up to > the developer to help the container optimize its work. > > A new tag (<session-replication-trigger>) has been added to > JBoss-web.xml: > > <!ELEMENT jboss-web (class-loading?, security-domain?, context-root?, > virtual-host?, use-session-cookies?, > session-replication-trigger?, resource-env-ref*, > resource-ref* , ejb-ref* , ejb-local-ref*, depends*)> > > This tag determines when the container should consider that a > session must be replicated accross the cluster. Possible values are: > 1 - "SET_AND_GET" > 2 - "SET_AND_NON_PRIMITIVE_GET" (default value) > 3 - "SET" > > The first option is conservative but not optimal > (performance-wise): it will replicate the session even if its > content has not been modified but simply accessed > (getAttribute). As shown above, there is no deterministic way > to know if the content of an attribute is not itself > modified. It WAS the default value in the past (simply > because it was the only implementation available), which > explain why the perf will be improved now. > > The second option is conservative but will only replicate if > a non-primitive Object has been accessed (Integer, Long, > Double, Short, String, etc. which are immutables). We can > take that decision because the previous example cannot be > used to modify a session without calling setAttribute (as the > objects are immutable). It is the NEW default value. > > The third option considers that the developer will > explicitely call setAttribute on the session otherwise it > will not be automatically replicated. > > Tag examples: > > <session-replication-trigger>SET_AND_GET</session-replication-trigger> > or > > <session-replication-trigger>SET_AND_NON_PRIMITIVE_GET</sessio > n-replication- > trigger> > or > > <session-replication-trigger>SET</session-replication-trigger> > > > Furthermore, in the past, when a new session was created, two > replications were occuring (one for the creation, one when > setting the session). Now, these two steps are reduce to a > single step => a single replication. > > These two changes should improve the performance of your > current clustered Web Application (using Tomcat). > > Cheers, > > > Sacha > > > > > ------------------------------------------------------- > This SF.net email is sponsored by: SF.net Giveback Program. > Does SourceForge.net help you be more productive? Does it > help you create better code? SHARE THE LOVE, and help us > help YOU! Click Here: http://sourceforge.net/donate/ > _______________________________________________ > JBoss-Development mailing list > [EMAIL PROTECTED] > https://lists.sourceforge.net/lists/listinfo/jboss-development > ------------------------------------------------------- This SF.net email is sponsored by: SF.net Giveback Program. Does SourceForge.net help you be more productive? Does it help you create better code? SHARE THE LOVE, and help us help YOU! Click Here: http://sourceforge.net/donate/ _______________________________________________ JBoss-user mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/jboss-user
