TechTalk: Virtualizing Java in Java

On 12th December, I was speaking at JUG in Saint-Petersburg, Russia.

It was a long talk about using NanoCloud.

Below is video

and slide deck from event

My history with Big Data

Before I joined Cloudera, I hadn't had much formal experience with Big Data. But I had crossed paths with one of its major use cases before, so I found it easy to pick up the mindset. My previous big project involved a relational database hooked up to a web server. (more...)

HotSpot JVM garbage collection options cheat sheet (v3)

Two years ago I have published cheat sheet for garbage collection options in HotSpot JVM.

Recently I decided give that work some refreshing and today I'm publishing first HostSpot JVM options ref card covering generic GC options and CMS tuning. (G1 have got a plenty of tuning options during last (more...)

JVM deep dive at HighLoad++ 2013 (Moscow)

Today was speaking at HighLoad++ 2013 Moscow. I had two presentation covering deep internals of JVM. One about JIT compilation and other concerning pauseless garbage collection algorithms.

Slide decks are below (in Russian)

Java class finding tool: ClassFinder

I got into more coding again lately and that is a good thing I think. I’m a believer of the German saying “Wer rastet, der rostet” or in English: A rolling stone gathers no moss! Java seems to be my main programming language since quite a while now. But believe (more...)

Oracle Forms and Java 7u51

Java 7u51 is scheduled for release in January. It will have some consequences for you Forms installation that you need to address.

As far as I know there is no problems with using 7u51 on the server side, only on the client side.

Overview

Jar signing

7u51 requires you to sign all RIAs (Applets and Web Start applications).

Oracle already signs the standard jar (more...)

WebLogic Server and entropy

After input from Jacco H. Landlust and Edwin Biemond I have rewritten my post about entropy.

Overview

Entropy pool

In computing you often need random numbers. They are used for encrypting stuff but also for lots of other things.

For Linux servers random numbers are default provided by the /dev/random device. /dev/random is a pool of random bits (more...)

Writing to stdout and stderr Take II

A few years ago I wrote a post that describes how to print text to the App Engine output file, bypassing the verbose MessageBox statement with its text length limitation (AppEngine Output Tricks, Reporting, Logging, Etc). I recently employed that same technique for logging Taleo Connect Client output (more...)

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...)

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...)

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

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| Feb 25, 2013
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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...)