SJK (JVM diagnostic/troubleshoting tools) is learning new tricks.

SJK is small command line tool implementing number of helpful commands for JMV troubleshooting. Internally SJK is using same diagnostic APIs as standard JDK tools (e.g. jps, jstack, jmap, jconsole).

Recently I've made few noteworthy additions to SJK package and would like to announce them here.

Memory allocation rates (more...)

Almost named method arguments in JDK 8

Sometimes it would be really nice to have named method parameter in Java, this doesn't look likely for a long while but there is always another little work around, for example using a builder pattern to get similar behaviour, that will bridge the gap for a little bit. It occurred (more...)

Downloading JRockit and Java SE 6 from MOS

Oracle no longer posts updates of Java SE 6 and JRockit to its public download sites.

If you have a support contract you can download new updates from MOS.

You can locate the Java SE 6 downloads in this note “All Java SE Downloads on MOS (Doc ID 1439822.1)”.

(more...)

Java GC in Numbers – Compressed OOPs

Compressed OOPs (OOP – ordinary object pointer) is a technique reducing size of Java object in 64 bit environments. HotSpot wiki has a good article explaining details. Downside of this technique is what address uncompressing is required before accessing memory referenced by compressed OOPs. Instruction set (e.g. x86) may (more...)

How to implement Document Versioning with Couchbase

Introduction Developers are often asking me how to "version" documents with Couchbase 2.0. The short answer is: the clients and server do not expose such feature, but it is quite easy to implement. In this article I will use a basic approach, and you will be able to extend (more...)

SQL to NoSQL : Copy your data from MySQL to Couchbase

TL;DR: Look at the project on Github. Introduction During my last interactions with the Couchbase community, I had the question how can I easily import my data from my current database into Couchbase. And my answer was always the same: Take an ETL such as Talend to do it Just write a (more...)

Java GC in Numbers – Parallel Young Collection

This is a first articles in series, where I would like to study effect of various HotSpot JVM options on duration of STW pauses associated with garbage collection.

This article will study how number of parallel threads affects duration of young collection Stop-the-World pause. HotSpot JVM has several young GC (more...)

Problems running lots of X11 sessions concurrently when testing under Hudson/Jenkins

So we are running a quite a bit of automated UI testing and we have found over a large number of concurrent test nodes that even when the Xvnc plugin has correctly started that the environment is not always ready or reliable. This blog post looks at two changes we (more...)

Ad-hock diagnostic tools for JVM

There are bunch of graphical tools helping you to look inside of running JVM (VisualVm and JConsole are extremely helpful). Unfortunately, some times (almost always in my case), you may find yourself in SSH console on headless server side by side with your JVM (more...)

About Java class, HTTP POST and viewContentURL

As of PeopleTools 8.52 it is possible to use REST services for POST/GET functionality. However what do you do if you are on an older PeopleTools version, but still need to make a HTTP POST and then GET the response?

Continue reading

Netbeans 7.3 Available

Uncategorized
| Feb 25, 2013
Are you a netbeanie?

Introduction to Collated Views with Couchbase 2.0

Most of the applications have to deal with "master/detail" type of data: breweries and beer department and employees invoices and items  ... This is necessary for example to create application view like the following: With Couchbase, and many of the document oriented databases you have different ways to deal with this, (more...)

Is your WebLogic Server slooow? Might be because of low entropy

On Linux low entropy can cause certain operations to be very slow.

SSL operations need entropy to ensure randomness. Entropy is generated by the OS when you use the keyboard, the mouse or the disk.

If an SSL operation is missing entropy it will wait until enough is generated.

If (more...)

How to simulate Coherence node failure in JUnit test

Recently, I was working on renewed version of Coherence data loss listener. New version provides simple utility to attach partition loader to any cache. Such partition loader is guaranteed to be called for every partition of newly created cache or after partition has been lost. Unlike CacheStore, partition loader (more...)

Remote code execution in Java made trivial

SSH offers a very convenient way to execute shell scripts remotely. Code like

ssh myserver.acme.com << EOC
cd $APP_HOME
./start_my_stuff.sh
EOC

are fairly easy to write and read.

But while remote execution itself is easy, writing actual distributed code is total mess.

I’m a Java guy. I (more...)

Couchbase 101: Create views (MapReduce) from your Java application

When you are developing a new applications with Couchbase 2.0, you sometimes need to create view dynamically from your code. For example you may need this when you are installing your application, writing some test, or you can also use that when you are building frameworks, and wants to (more...)

Making Eclipse IDE Supports JSF 2.0

Uncategorized
| Oct 22, 2012

Autocomplete was not working for JSF tags in my Eclipse. I googled it and finally found the solution on http://www.mkyong.com/jsf2/how-to-make-eclipse-ide-supports-jsf-2-0/

Thanx Mkyong.

The different thing I did is; I downloaded javax.faces-2.xx.xx.jar and saved in a specific folder. Then I created a user library with this jar. I did not use “jsf-api-xxx.jar and jsf-impl-xxx.jar“.


Missing IPV6 address for local network interfaces causes service timeout

Year ago I installed Weblogic server + Oralce database server for a customer. Few months later my colleagues asked me whether something has changed in the environment or if something happened at the data center, because they started to see Java exceptions for unknown hostname for a web service they were calling and this was happening only from time to time. We’ve checked the firewall rules, DNS and all the stuff, but everything seemed to be working fine. The only solution by that time they came out was to add the hostname to the hosts file of the Weblogic server. (more...)

Separate docs for MySQL Connectors

The MySQL documentation section has always had this Topic Guides page containing links to the docs for the various MySQL Connectors -- the official database drivers for various languages and programming technologies. That is the most convenient way to get the information for each Connector in PDF form, rather than downloading the entire Ref Man PDF. For HTML, it was more of a shortcut, because

Generating an EJB SDO Service Interface for Oracle SOA Suite

In Oracle SOA Suite you can use the EJB adapter as a reference or service in your composite applications. The EJB adapter has a flexible binding integration, there are 3 ways for integrating the remote interface with your composite.

First you have the java interface way which I described here (more...)