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SEARCH KEYWORD -- Memory leak

  PHP's Output Buffering

While profiling our application I came across a a rather strange memory usage by the ob_start() function. We do use ob_start() quite a bit to defer output of data, which is a common thing in many applications. What was unusual is that 16 calls to ob_start() up chewing through almost 700kb of memory, given that the data being buffered rarely exceeds 1-2kb, this was quite unusual. I started looking at the C code of the ob_start() function and found this interesting bit of code inside php_sta...

   PHP,Memory,ob_start(),source,40kB     2011-12-08 10:20:32

  The internals of slice in GoLang

There are 3 components of slice:a) Pointer: Points to the start position of slice in the underlying array;b) length (type is int): the number of the valid elements of the slice;b) capacity (type is int): the total number of slots of the slice. Check the following code: package main import ( "fmt" "unsafe" ) func main() { var s1 []int fmt.Println(unsafe.Sizeof(s1)) } The result is 24 on my 64-bit system (The pointer and int both occupy 8 bytes). In the next example, I will use gdb to poke t...

   GOLANG,SLICE     2019-06-30 02:55:22

  Why is single threaded Redis so fast

Redis is a high-performance, in-memory key-value database. According to official test reports, it can support around 100,000 QPS (queries per second) on a single machine. However, Redis uses a single-threaded architecture in its design. Why does Redis still have such high performance with a single-threaded design? Wouldn't it be better to use multiple threads for concurrent request processing? In this article, let's explore why Redis has a single-threaded architecture and still maintains its spe...

   REDIS,SINGLE-THREADED,MULTI-THREADING     2023-02-28 05:16:22

  12 useful Chrome commands

Many useful features of Chrome don't show up on its menus. You can access them through the chrome:// command. In this article we will introduce 12 useful chrome:// commands. 1. chrome://flags It can be used to turn on or turn off some chrome features. 2. chrome://dns This command will show the domain name list caught by the browser. 3. chrome://downloads You can access this through chrome menu as well. The shortcut is Ctrl+J 4. chrome://extensions This command equals to Menu->Tools->Ext...

   Chrome,chrome://     2013-01-25 04:38:03

  C++ for the Real-Time Web

C++? Why on Earth? C++ seems like one of the least likely languages to write a web application in. C++ is associated with complexity, both with language design and the need to manually manage memory. Programming in C++ unleashes a whole class of bugs associated with memory corruption and memory allocation. This is a trade off for giving more power to the developer along generally being much faster than equivalent programs in languages such as Python or Ruby. Real-time Web as a Use Case Making...

   C++,Web development,Real time     2012-01-30 06:00:20

  What is goroutine?

Casual Talk Golang is quite enjoyable to write, aside from the tedious if err != nil checks. One of the fundamental reasons for the joy is goroutine, a core feature of Golang. Understanding goroutines in detail is worthwhile, as they contribute significantly to the pleasure of working with Golang. So, let's talk about goroutines, hoping to provide some insights to the readers. TL;DR: We'll start by talking about assembling a computer, then delve into some concepts of the operating system, such ...

   EXPLANATION,GOLANG,GOROUTINE     2024-01-21 03:26:10

  Unix directory hierarchy history

As a beginner user of Unix or Linux, people would frequently get confused about the use of different directories of the system.  For example, there is a /bin directory under root(/), it is used to store binary files. However, there are /usr/bin and /usr/local/bin under /usr which are used for storing binary files as well. Some systems even have /opt/bin. What are the differences among them? Though there are articles explaining different directories in *nix such as Filesystem Hierarchy Stan...

   UNIX,LINUX,FILESSYTEM,DIRECTORY HIERARCHY,HISTORY     2016-10-21 23:47:17

  Fastjson just fixed a bug which might cause out of memory issue

Fastjson just fixed a bug which might cause service down a few days ago. This bug is caused by some mishandling of special character \x which is an escaped character to indicate hexdecimal number. The impact of this bug would be big if the attacker constructs a malicious data which would cause the service down.  The code which causes the issue is in com.alibaba.fastjson.parser.JSONLexerBase#scanString, when a JSON string is passed in, fastjson would parse the string character by c...

   FASTJSON,ALIBABA,BUG,NEWS     2019-09-07 06:03:49

  ByteBuffer in Java

ByteBuffer is introduced in java.nio since Java 1.4. It provides a way of representing raw structured data such as from a file or from network. It enables fast access of underlying data compared to traditional ways like byte[] Prior to Java 1.4, if you want to represent a structured raw data, you need to create a byte[] and then having a set of checks to delimit the byte array to get the expected tokens. There are three ways to create a ByteBuffer: Wrapping an exiting array by calling ByteBuffe...

   JAVA,BYTEBUFFER,ALLOCATION     2015-07-08 03:17:44

  Server monitoring shell scripts

There are many open source server monitoring software such as cacti and nagios. Besides these, can we write our own shell scripts to monitor them? The shell scripts written by ourselves can fulfill our special requirements better and have a more detailed coverage. Below are some commonly used shell scripts used by Evangelist, an Oracle DBA. 1. Check network gateway traffic #!/bin/bash #network #Mike.Xu while : ; do time='date +%m"-"%d" "%k":"%M' day='date +%m"-"%d' rx_before='...

   Server monitor,CPU,memory,shell     2013-08-30 21:56:14

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