Skip to main content

Java Applet CACHE_VERSION Mac v/s Windows

Java Applets uses a property called as CACHE_VERSION which is of format 4.0.5.452d that is comprised of 4 hexadecimal values separated by ".". The Applet plug-in uses this to determine whether to download new Jars or not. The sun documentation says that applet plugin would download the new jars if the CACHE_VERSION is higher than the previous one. My findings on this:

Windows plugin in IE/FF/Chrome/"Safari on windows" all will download new jars regardless of whether the jar cache version is greater or not. Earlier our version was 4.0.5.XXX, I tried updating version to 4.0.4.XXX or even 1.2.3.XXX and windows would happily download it.

We recently ran into an issue where applet would not work fro some mac users and it was random, the culprit was that during one deployment our operations team had updated jar as 4.0.6.XXX and we use XXX as svn changelist number of the jar file so we never changed the "4.0.5" portion. When the new build was deployed the jar version was again set to "4.0.5.XXX" in the jsp page.

The reason was the MAC Java plugin enforces the rules mentioned by Sun to download jars only if CACHE_VERSION is greater than the previous one. Changing the version to 5.2.1.XXX solved the issue and we changed the build also to reflect 5.2.1

Comments

Popular posts from this blog

RabbitMQ java clients for beginners

Here is a sample of a consumer and producer example for RabbitMQ. The steps are
Download ErlangDownload Rabbit MQ ServerDownload Rabbit MQ Java client jarsCompile and run the below two class and you are done.
This sample create a Durable Exchange, Queue and a Message. You will have to start the consumer first before you start the for the first time.

For more information on AMQP, Exchanges, Queues, read this excellent tutorial
http://blogs.digitar.com/jjww/2009/01/rabbits-and-warrens/

+++++++++++++++++RabbitMQProducer.java+++++++++++++++++++++++++++
import com.rabbitmq.client.Connection; import com.rabbitmq.client.Channel; import com.rabbitmq.client.*; public class RabbitMQProducer { public static void main(String []args) throws Exception { ConnectionFactory factory = new ConnectionFactory(); factory.setUsername("guest"); factory.setPassword("guest"); factory.setVirtualHost("/"); factory.setHost("127.0.0.1"); factory.setPort(5672); Conne…

Logging to Graphite monitoring tool from java

We use Graphite as a tool for monitoring some stats and watch trends. A requirement is to monitor impact of new releases as build is deployed to app nodes to see if things like
1) Has the memcache usage increased.
2) Has the no of Java exceptions went up.
3) Is the app using more tomcat threads.
Here is a screenshot

We changed the installer to log a deploy event when a new build is deployed. I wrote a simple spring bean to log graphite events using java. Logging to graphite is easy, all you need to do is open a socket and send lines of events.
import org.slf4j.Logger;import org.slf4j.LoggerFactory; import java.io.OutputStreamWriter; import java.io.Writer; import java.net.Socket; import java.util.HashMap; import java.util.Map; public class GraphiteLogger { private static final Logger logger = LoggerFactory.getLogger(GraphiteLogger.class); private String graphiteHost; private int graphitePort; public String getGraphiteHost() { return graphiteHost; } public void setGraphite…

What a rocky start to labor day weekend

Woke up by earthquake at 7:00 AM in morning and then couldn't get to sleep. I took a bath, made my tea and started checking emails and saw that after last night deployment three storage node out of 100s of nodes were running into Full GC. What was special about the 3 nodes was that each one was in a different Data centre but it was named same app02.  This got me curious I asked the node to be taken out of rotation and take a heap dump.  Yesterday night a new release has happened and I had upgraded spymemcached library version as new relic now natively supports instrumentation on it so it was a suspect. And the hunch was a bullseye, the heap dump clearly showed it taking 1.3G and full GCs were taking 6 sec but not claiming anything.



I have a quartz job in each jvm that takes a thread dump every 5 minutes and saves last 300 of them, checking few of them quickly showed a common thread among all 3 data centres. It seems there was a long running job that was trying to replicate pending…