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  Java Sequential IO Performance

Many applications record a series of events to file-based storage for later use.  This can be anything from logging and auditing, through to keeping a transaction redo log in an event sourced design or its close relative CQRS.  Java has a number of means by which a file can be sequentially written to, or read back again.  This article explores some of these mechanisms to understand their performance characteristics.  For the scope of this article I will be using pre-a...

   Java,IO,Sequential,Blocking     2012-02-23 07:09:10

  Generate certificate with cRLDistributionPoints extension using OpenSSL

In an X509 certificate, the cRLDistributionPoints extension provides a mechanism for the certificate validator to retrieve a CRL(Certificate Revocation List) which can be used to verify whether the given certificate is revoked.   A cRLDistributionPoints extension can contain one or more DistributionPoints where the CRL can be retrieved from. Each DistributionPoint consists of three fields,each of which is optional: distributionPoint : it contains either a SEQUENCE of general...

   X509,OPENSSL,CERTIFICATE,CRLDISTRIBUTIONPOINT,EXTENSION     2015-10-22 03:41:11

  Finding selected checkbox items in a JSF dataTable

This is one of those problems that I couldn’t find a complete example for when I needed it, so hopefully this will save somebody else the extra time it took me to piece it together. We frequently need to have data tables in our UI, and allow the user to select a subset of those items for action. In JavaServer Faces, this means having a DataTable, each row having its own checkbox. But when the action is triggered, how to we find which items the user has selected. The first step is to ...

   JavaServer Faces,JSF,Datatable,Checkbox,Example     2012-01-03 03:02:46

  The basics of Client/Server socket programming

  While Client/Server communication model is ubiquitous nowadays, most of them involve socket programming knowledge. In this post, I will introduce some rudimentary aspects of it: (1) Short/Long-lived TCP connection.Short-lived TCP connection refers to following pattern: Client creates a connection to server; send message, then close the connection. If Client wants to transmit information again, repeat the above steps. Because establishing and destroying TCP s...

       2017-09-26 19:43:10

  Resolve high CPU usage issue caused by file_get_contents in PHP

Sometimes a Linux server which runs Nginx + PHP-CGI(php-fpm) web service may experience sudden system load increase and the CPU usage is around 100% for many php-cgi processes when checking with top command. If this happens, file_get_contents may be the cause if it's used in the PHP script. In lots of web applications, normally there are lots of API requests based on HTTP. Many PHP developers like to use file_get_contents("http://example.com/") to get the API response because it's simple to...

   PHP,FILE_GET_CONTENTS,PHP-CGI     2018-11-09 21:35:00

  Efficiency of code execution

If you want to optimize your program codes, you need to find their Hotspot, i.e, the codes which are executed most frequently. If you can optimize this portion of codes a bit, you may gain much improvement of your code efficiency. Here I give you three examples about efficiency of code execution.1. PHP's Getter and Setter (From Reddit)This example a quite simple, you can skip it if you want.Consider the code below, we can find it's slower when we use Getter/Setter method to read a member variabl...

   Code, Efficiency,Analysis,Trick     2012-07-13 10:59:21

  Walking through doorways causes forgetting, new research shows

We’ve all experienced it: The frustration of entering a room and forgetting what we were going to do. Or get. Or find.New research from University of Notre Dame Psychology ProfessorGabriel Radvansky suggests that passing through doorways is the cause of these memory lapses.“Entering or exiting through a doorway serves as an ‘event boundary’ in the mind, which separates episodes of activity and files them away,” Radvansky explains.“Recalling the decision...

   Memory loss,Doorway,Forget,Advice     2011-11-21 10:11:19

  Advanced event registration models

On this page I explain the two advanced event registration models: W3C’s and Microsoft’s. Since neither is cross–browser supported, their use is, for the moment, deprecated. W3C and Microsoft have both developed their own event registration model to replace Netscape’s traditional model. Though I’m not impressed by the Microsoft model, W3C’s is very good, except for one crucial vagueness. Unfortunately few browsers support it at the moment. W3C W3Câ...

   JavaScript,Event model,this,bubble,capturing     2011-12-27 09:20:44

  Deep clone of JavaScript object

In JavaScript world, it's frequently seen object clone. Normally when creating a clone of an object, it's only the reference being cloned but not all contents. In some scenarioes, it's desired to clone all the content instead of just the reference such that any change made to the cloned object will not change the original object. Differences between shallow clone and deep clone can be as simple as: Shallow clone : Only the object reference is cloned but not the content Deep clone : Clone all co...

   JAAVSCRIPT,DEEP CLONE,DEEP COPY,SHALLOW CLONE,SHALLOW COPY     2016-10-31 00:27:24

  JavaScript: It's a Language, Not a Community

There's nothing like jsconf for bringing out the meta! Since the conference ended two blog posts have created a lot of buzz, at least within my own twitter bubble. First, Rebecca Murphey's JavaScript: It's a Language, Not a Religion. I take Rebecca's post as a cautionary tale about the dangers of hero-worship and the tendency to assume that the people we respect in one sphere share our views in other spheres. I bring it up here not because I want to discuss the content of her post but b...

   JavaScript,Language,Community     2012-04-07 10:37:40

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