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SEARCH KEYWORD -- Data structure alignment

  MaxHeapSize in JVM

MaxHeapSize is an option which is to set the JVM maximum heap size can be allocated. We can specify the MaxHeapSize as VM argument when we run the program by setting -XX:MaxHeapSize=, here can be 2M, 20M, 200M etc. We can also view the current MaxHeapSize set by setting different JVM options. To view the MaxHeapSize, we can use two JVM options : -XX:+PrintFlagsFinal and -XX:+PrintCommandLineFlags. Below is one example when running -XX:+PrintFlagsFinal: bool MaxFDLimit ...

   JVM,MaxHeapSize,Alignment     2014-06-17 07:01:50

  How big is sizeof structure?

First let's see the codes of a structure: struct node{ int a; int b; }; Question : What's sizeof(node)? The answer is very simple, on a 32 bit machine, an int will take 4 bytes and two ints will take 8 bytes. So sizeof(node) is 8. The answer for the above codes is 8, then how about the following structure: struct node{ char a; int b; }; Question : Then what's sizeof(node) now? int takes 4 bytes, char takes 1 bytes, is the answer 5? Now the answer may not be 5, on some mac...

   Data structure alignment, pack     2012-10-29 12:13:37

  Smuggling data in pointers

While reading up on The ABA Problem I came across a fantastic hack.  The ABA problem, in a nutshell, results from the inability to atomically access both a pointer and a "marked" bit at the same time (read the wikipedia page).  One fun, but very hackish solution is to "smuggle" data in a pointer.  Example:#include "stdio.h"void * smuggle(void * ptr, int value){  return (void *)( (long long)ptr | (value & 3) );}int recoverData(void * ptr){  return (long long)ptr &...

   C,Pointer,Bit,Data,Atomic,Smuggle     2011-11-14 08:15:59

  Successful Web Design: It’s All About The Details

While the tools are out there for almost anyone to build a website, the most successful designs all share a few characteristics. These sites tend to be organized well, have great content and have all the design details in order. Small parts of your site, from alignment and bolding to contrast and color, can make or break the design. Taking care of the details before your project is published will ensure the page has a clean overall feel. Unorganized design and lack of attention to detail ...

   Web design,Details,Success     2012-04-16 13:38:56

  How big are PHP arrays (and values) really? (Hint: BIG!)

Upfront I want to thank Johannes and Tyrael for their help in finding some of the more hidden memory usage. In this post I want to investigate the memory usage of PHP arrays (and values in general) using the following script as an example, which creates 100000 unique integer array elements and measures the resulting memory usage: <?php $startMemory = memory_get_usage(); $array = range(1, 100000); echo memory_get_usage() - $startMemory, ' bytes'; How much would you expect it to ...

   PHP,Array,Memory occupation,Garbage collection     2011-12-16 10:06:04

  JSON in JavaScript

When sending an AJAX request to the server, the response can have two formats : XMLHttpRequest.responseXML to access data with XML format and XMLHttpRequest.responseText to access data with string format. XML is the standard data transfer format, but one weakness is it's troublesome to parse and retrieve the data. JSON(JavaScript Object Notation) is a light weight data interchange format, we call it the JavaScript object representation. The advantage of using JSON as the data format is itself is...

   JSON,JavaScript     2013-05-04 23:25:57

  3 meanings of Stack

We may frequently see stack when we read programming books. But many times we may be confused about the different meanings of it. This term actually has three common meanings. Here we explain the three different meanings of Stack in programming. 1. Data structure The first meaning of Stack defines a method for storing data. Its feature is LIFO9Last In First Out). In this data structure, data are accumulated level by level. The data last put in is added at the top of the stack. When using the dat...

   Stack,Memory,Data structure     2014-02-24 04:56:46

  C programming tips in SPARC architecture

If you are a newbie of C programmers in SPARC architecture (For example, working on Solaris), you should pay attention to the following tips:(1) By default, SPARC is big-endian (For Endianness, you can refer http://en.wikipedia.org/wiki/Endianness). It means for an integer (short, int, long, etc), the MSB will be stored in the lower address, while the LSB will be stored in the higher address. (2) SPARC requires byte-alignment. It means for a short (2 bytes long) variable, the star...

   C     2014-06-01 03:56:30

  How to let Google index AJAX contents?

There are lots of websites containing only one page now with the popularity of AJAX. The website will load different contents according to different inputs from users. This approach provides good user experience and it also helps save bandwidth, the drawback is that AJAX contents are not easy to be indexed by search engines. For example, if you have a website: http://example.com Users can see different contents with the appended # structure in the URL: http://example.com#1 http://example.com#2 h...

   AJAX,Search engine,Google,History     2013-07-16 00:47:14

  Beginners guide to Linux directory structure

Have you ever looked in your / directory, you’ll see a lot of directories. Here we are presenting beginners guide to linux directory structure explaining what they mean and what are the contents of these directories.Screenshot of contents of root directory: /This is called root partition. All files and directories start with root partition. Write privileges under this directory are avaible with root user only. Not to confuse it with root user’s home directory, know the ...

   Linux,File system structure,Beginner's guide     2012-04-20 12:19:32

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