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  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

  Reflection in Java

What is Reflection? Reflection is a feature in Java that allows a program to obtain information about itself at runtime and dynamically manipulate the properties, methods, and constructors of classes or objects. With reflection, we can instantiate objects, call methods, and set properties without knowing the exact class name beforehand. The core of the reflection mechanism is the Class object, which represents a class. The Java Virtual Machine (JVM) automatically creates this Class object when i...

   JAVA REFLECTION,TUTORIAL,FIELD,METHOD     2024-06-27 07:52:12

  Install Kubernetes with minikube and docker on Ubuntu

When someone just wants to play around Kubernetes on its local environment without accessing to Cloud provider resources, one can set Kubernetes up on local environment with minikube with single node mode. This post will provide a simple guideline on how to set up KUbernetes with minikube and docker on Ubuntu. Before all the steps can be started, you may need to first set up kubectl which is a command line tool to operate on Kubernetes resources. Post that, can ensure that docker is installed on...

   KUBERNETES,MINIKUBE,DOCKER,UBUNTU     2021-06-01 05:37:40

  Be careful about nil check on interface in GoLang

nil check is frequently seen in GoLang code especially for error check since GoLang's special error handling convention. In most cases, nil check is straight forward, but in interface case, it's a bit different and special care needs to be taken. Take a look at below code snippet and guess what the output will be. package main import ( "bytes" "fmt" "io" ) func check(w io.Writer) { if w != nil { fmt.Println("w is not nil") } fmt.Printf("w is %+v\n", w) } func main() { var b *bytes.B...

   INTERFACE,GOLANG,NIL CHECK,NIL TYPE,NIL VALUE     2019-04-06 07:47:07

  A trap in PDOStatement::bindParam

First, let's check out below codes: <?php $dbh = new PDO('mysql:host=localhost;dbname=test', "test"); $query = <<prepare($query); $bind_params = array(':username' => "laruence", ':password' => "weibo"); foreach( $bind_params as $key => $value ){ $statement->bindParam($key, $value); } $statement->execute(); What is the SQL executed finally? Is there any problem with above codes? Many people may think the query executed is : INSERT INTO `user` (`username`, `password...

   PHP,Trap,bindParam     2013-08-29 10:48:55

  About tmpfs

tmpfs is another confusing name in Linux kernel, its implementation is in mm/shmem.c, shmem has no relation to tmpfs at first glance although we know tmpfs is based on memory. We can understand why we use this name by seeing where this is used. In a desktop Linux system, tmpfs is loaded usually: % grep tmpfs /proc/mountsdevtmpfs /dev devtmpfs rw,seclabel,nosuid,relatime,size=1958956k,nr_inodes=489739,mode=755 0 0tmpfs /dev/shm tmpfs rw,seclabel,nosuid,nodev,relatime 0 0tmpfs /run tmpfs rw,seclab...

   tmpfs,Linux,file system     2013-06-14 12:10:56

  Mock Solutions for GoLang Unit Test

In Go development, Unit Test is inevitable. And it is essential to use Mock when writing Unit Tests. Mock can help test isolate the business logic it depends on, enabling it to compile, link, and run independently. Mock needs Stub. Stub function replaces the real business logic function, returns the required result, and assists the test. I involved the related test code for Controllers while writing Kubernetes Operator recently, and there would be mocks for GRPC and HT...

   UNIT TEST,TESTIFY,GOSTUB,GOMOCK     2020-10-31 21:59:15

  New Features to Look Out for in Xcode 9

When we say Xcode, we mean a designing toolset which is completely packed with features. Using this Xcode, developers can create applications for platforms such as the Apple TV, the iPad, Apple Watch, and the iPhones and even for the Macintosh. The development system for Xcode has a mixture of features. These are called the instrument analysis tool, simulators, and the ever important OS frameworks which are present in the package in a variety of form of tvOS SDKs, iOS SDKs, watchOS SDKs, and the...

   XCODE,IPHONE,XCODE9     2017-09-26 06:31:30

  Strict mode in JavaScript

1. Introduction In addition to normal mode, ECMAScript 5 includes the other mode : strict mode. It means it will make JavaScript codes execute in a more strict environment. The purposes to have strict mode are: Remove some unreasonable and parts of JavaScript syntax. Reduce some of the quirk behaviors. Remove some insecure parts of code execution. Make the execution environment more secure Improve interpret efficiency and increase the execution speed Build foundation for future JavaScript versi...

   JavaScript, Strict mode. Introduction     2013-01-17 05:00:26

  Save QWidget as image

Qt library is an excellent GUI library for C++ programmers developed by Nokia and now is an open source project. Often, we may use QPainter to draw strings, lines or images on a QWidget. We can override the QWidget's paintEvent() method when we want to use QPianter object to draw something on a QWidget. If we want to save the items drawn on QWidget as image for later reference, what can we do? We can save a QWidget as an image. Here is the code for achieving this: QPixmap pixmap(this->size())...

   Qt,C++,QWidget,Image     2012-08-19 12:01:18

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