Notes From Scandev2011-Yet More Performance Tuning

Spokesperson:Kirk Pepperdine

I guess this presentation should be more productive. I think Kirk is a great guy on performance tuning, I find his presentation very helpful for every java developer. But it could be more informative, because he made a demo but most of the room was not aware of what is going on. And nobody asked any question after his presentation.
The key point of perfomance tuning we should focus on 4 factors :

• Actors(Usage Patterns)
• Application(Locks, External Systems etc.)
• JVM(Memory, Process)
• HW/OS(CPU, Memory, Disk IO, Network)
• If nothing dominates than check the resources.(This is my addition to 4 factors :))

We have to tune the system before we tune the Application he says. And he says first Diagnostic than Diagnose.

Some performance profile tools: Apache JMeter, HP JMeter, VisualVM, JProfiler, HP LoadRunner etc.

Notes From Scandev2011-JDK7

Spokesperson:Henrik Ståhl

-JDK7 Not a revolution, but an evolution!

This was an informative presentation of new features in JDK7 and Java SE 8

Henrik talked about the enhancements, and Oracle's strategy on Java. He said that the "Evil Company" wants to support Java for its own good. Oracle bought Java for insurance! He said that there exists some open positions in JDK development team, if you are interested you may contact him. May be you want to be one of 10 thousand Java developer in Oracle.

Some enhancements in JDK7: Strings in switch statements, underscore in variable names, multi catch for exception handling, diamond operator etc...

Other Features in Detail

vm : JSR 292: Support for dynamically-typed languages (InvokeDynamic)
Strict class-file checking [NEW]
lang : JSR 334: Small language enhancements (Project Coin)
core Upgrade class-loader architecture
Method to close a URLClassLoader
Concurrency and collections updates (jsr166y)
i18n : Unicode 6.0
Locale enhancement
Separate user locale and user-interface locale
ionet : JSR 203: More new I/O APIs for the Java platform (NIO.2) (turorial on File I/O)
NIO.2 filesystem provider for zip/jar archives
SCTP (Stream Control Transmission Protocol)
SDP (Sockets Direct Protocol)
Use the Windows Vista IPv6 stack
TLS 1.2
sec :Elliptic-curve cryptography (ECC)
jdbc :JDBC 4.1
client : XRender pipeline for Java 2D
Create new platform APIs for 6u10 graphics features
Nimbus look-and-feel for Swing
Swing JLayer component
web :Update the XML stack
mgmt :Enhanced JMX Agent and MBeans [NEW]

+CSS support for Javadoc :)

Thanks to Henrik!

Notes From Scandev2011-Alistair Cockburn

Scandev2011 started with an introductory speech coming from Emily Bache.
Than the stage was all Alistair Cockburn's, and he talked about shaping the process of software development. He mentioned that, why people are always being beyond the schedule in SW project. He thinks that the software development process is going to be emulated by other sectors in 10 or 20 years by now(I hope so?). And he indicated that every team has to improve themselves on a changing environment. But sometimes the project cost and the team revenue doesn't rise with the same acceleration ratio.

The main idea in his speech was, software development is a cooperative game…

And people should understand the importance of remind-inform-inspire triangle. And the power of communication by face to face talk.

This was an impressive and thoughtful speech to listen.

Android sdk installation jdk not found error

When there’s a pop up say JDK not found please download and install. First do what it says, than if still same error exists Just press ‘back’ button and then press again ‘next’ button. And you can pass the validation!

SLF4J - The Simple Logging Facade for Java

SL4J allows us to use the desired logger mechanism at deployment time. SL4J supports

-Log4j
-java.util.logging
-NOP
-Simple
-JCL

If you want to change the way you log, just change the bridging .jar file and restart the application.

http://www.slf4j.org/index.html

Ubuntu root password change

~sudo passwd root
~enter your login username password
~Enter your new UNIX Password
~su root
~Enter your new UNIX Password

that is it

Search a date range using a date range in sql

select count(*) from tablename where (@startDate between startDate and endDate )

or (@endDate between startDate and endDate)

or (@startDate <> endDate )


If this sql returns greater than 0, that means there exists a conflict with your date interval and the db working set.