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  Build Hadoop environment in Linux

Hadoop standalone installation: 1. Install JDK Install JDK with below command: sudo apt-get install sun-java6-jdk Configure Java environment, open /etc/profile, add below contents: export JAVA_HOME = (Java installation directory) export CLASSPATH =".:$JAVA_HOME/lib:$CLASSPATH" export PATH = "$JAVA_HOME/:PATH" Verify installation of Java Type java --version, if it outputs Java version information, then Java is successfully installed. 2. Install SSH Install SSH with below command: sudo ...

   Hadoop.Linux,Configuration     2013-07-31 23:22:27

  Java Interview Questions

Currently there are many articles online which summarize the list of Java interview questions. Some cover lots of basic questions and some cover some specific questions in specific area such as multithreading. In this post, we will not cover the really basic questions, we will cover something different. For basic question, you can read Java Interview Questions。 Basic What is primitive data type? How many primitive data types in Java? What are they? -- A primitive type is prede...

   JAVA,SECURITY,INTERVIEW,CAREER,MULTITHREADING,QUESTION,JAVA INTERVIEW,JAVA CORE     2019-01-21 07:07:08

  Which web front-end framework to choose?

When doing web design, we often need to choose which front-end framework to use in order to provide great user experience and simplify the development. Also, compatibility problem can be solved by using front-end frameworks. Here is a list of front-end frameworks. Which one are you using? Which one do you prefer?1. Apache FlexApache Flex, is a software development kit for the development and deployment of cross-platform rich Internet applications based on the Adobe Flash platform. Initially deve...

   Web design,Front-end,Framework     2012-07-30 13:57:26

  The False Ideals of the Web

WE who love the Internet love the fact that so many people contribute to it. It’s hard to believe that skeptics once worried about whether anyone would have anything worthwhile to say online. There is, however, an outdated brand of digital orthodoxy that ought to be retired. In this worldview, the Internet is a never-ending battle of good guys who love freedom against bad guys like old-fashioned Hollywood media moguls. The bad guys want to strengthen copyright law, and make ...

   Web,False idea,Free,SOPA     2012-01-19 10:24:25

  Good to Great Python reads

A col­lec­tion of python “must reads”:The Python yield key­word explainedPython’s super() con­sid­ered super!Under­stand­ing Python DecoratorsWhat is a meta­class in Python?Meta­classes DemystifiedTry/Catch for val­i­da­tion or speed?Python (and Python C API): __new__ ver­sus __init__Python “self” keywordPython and the Prin­ci­ple of Least AstonishmentA Curi­ous Course on Corou­tines and Concurr...

   Python,Reference,eBook,Reading Material     2011-11-15 11:46:12

  Vim anti-patterns

The benefits of getting to grips with Vim are immense in terms of editing speed and maintaining your “flow” when you’re on a roll, whether writing code, poetry, or prose, but because the learning curve is so steep for a text editor, it’s very easy to retain habits from your time learning the editor that stick with you well into mastery. Because Vim makes you so fast and fluent, it’s especially hard to root these out because you might not even notice them...

   Vim,Anti-pattern,macro,syntax     2012-02-08 10:06:15

  Why accessing Java HashMap may cause infinite loop in concurrent environment

HashMap in Java is frequently used to handle key/value pairs. But it is not a good candidate to be used in concurrent environment where ConcurrentHashMap should be used instead. If used in concurrent environment, it may cause lots of unexpected behavior even including make the program getting into an infinite loop situation. To understand how this can happen, let's first discuss how HaspMap works internally. In this post we will use implementation of HashMap before Java 8 as example, Java 8 prov...

   JAVA,HASHMAP,INFINITE LOOP     2020-03-29 01:47:00

  Why programmers work at night

A popular saying goes that Programmers are machines that turn caffeine into code. And sure enough, ask a random programmer when they do their best work and there’s a high chance they will admit to a lot of late nights. Some earlier, some later. A popular trend is to get up at 4am and get some work done before the day’s craziness begins. Others like going to bed at 4am. At the gist of all this is avoiding distractions. But you could just lock the door, what’s so special a...

   Programmer,Sleep,Later,Efficiency,Habit     2011-12-16 10:13:27

  Optimization Tricks used by the Lockless Memory Allocator

With the releasing of the Lockless Memory Allocator under the GPL version 3.0 license, we can now discuss more of the optimization tricks used inside it. Many of these are things you wouldn't want to use in normal code. However, when speed is the ultimate goal, sometimes we need to break a few rules and use code that is a little sneaky.The SlabA slab is a well-known technique for allocating fixed size objects. For a given object size, a chunk of memory is divided up into smaller regions of that ...

   Optimization,Memory allocation     2011-11-16 08:02:16

  SQLite C/C++ function interfaces

Some simple introduction to the SQLite function interfaces. First let's check some error codes defined in SQLite3 (They are in SQLite3.h file in the SQLite installation).#define SQLITE_OK           0   /* Successful result */  /* beginning-of-error-codes */  #define SQLITE_ERROR        1   /* SQL error or missing database */  #define SQLITE_INTERNAL     2&nb...

   SQLite,Function interface,C/C++     2012-07-04 12:23:43