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  What is cache penetration, cache breakdown and cache avalanche?

When designing and developing highly available system, cache is an very important consideration. It is useful to cache some frequently accessed data so that they can be accessed quickly and also cache can protect the downstream system like DB from being hit too often.  To provide better cache design in large systems, some problems may need to be considered first. In this post, we will talk about some frequently discussed cache problems and mitigation plans. Cache penetration Cache penetrati...

   SYSTEM DESIGN,CACHE PENETRATION,CACHE BREAKDOWN,CACHE AVALANCHE     2020-04-10 08:43:00

  Guide to Clearing Storage Space on a Macbook

Macbooks are pretty notorious when it comes to what storage space you have available. Those few gigabytes that you have will disappear in no time if you are not careful. The whole issue becomes even more problematic for people who are not that familiar with Macbooks or have switched from another computer. And if you do not pay attention, it will not take too long before you have next to no storage space on the hard drive. Leaving only a few gigabytes of free space will significantly reduce the ...

   MACBOOK,APPLE,DATA STORAGE     2020-08-08 00:21:42

  Find files by size in Linux

In Linux systems, you may encounter a situation where there is no enough space on the system while you are trying to install some new packages or writing some data. In this case, you may want to clear some unneeded files. A frequent need will be find the largest files in the system so that they can be deleted first and disk space can be released quickly. In this post, we will show a simple command to find files by size so that we know what files are taking the specified space on the system, This...

   LINUX,FILESIZE,FIND     2020-04-25 08:02:45

  Steve Jobs's prediction about wireless,iPad and App Store in 1983

1983 was still a year uncultivated. That year, Apple released the first personal computer Apple Lisa with graphical user interface in the world, TCP/IP was released less than two years, the Internet was basically still a wasteland. General people had few knowledge about computer. Steve Jobs still needed to start with "What is the computer" in his speech. Today, we have become accustomed to social networking, smart phones and mobile Internet, it was really unbelievable at that time. That ye...

   Steve Jobs, record,Apple,prediction     2012-10-03 04:37:17

  How Google Tests Software - Part Three

Lots of questions in the comments to the last two posts. I am not ignoring them. Hopefully many of them will be answered here and in following posts. I am just getting started on this topic.At Google, quality is not equal to test. Yes I am sure that is true elsewhere too. “Quality cannot be tested in” is so cliché it has to be true. From automobiles to software if it isn’t built right in the first place then it is never going to be right. Ask any car company that has ever h...

   Google,Software,Testing,Quality,Fidelity     2011-03-22 14:31:00

  Net Neutrality is Dead - and Web Development Will Never Be The Same Again

Against the wishes of web users and tech businesses alike, the FCC has pushed through regulations to kill net neutrality. Here’s what that means for web developers. On December 14, 2017, the FCC voted in a 3-2 decision to roll back the Obama administration’s 2015 net neutrality rules. These policies, which demanded stronger oversight for broadband companies and internet service providers, ensured that all data on the web was treated equally. Most importantly, they prevented web traf...

       2019-05-02 21:55:53

  New member in Samsung family

According to The Verge, Samsung will enhance its product army by unveiling two new tablet devices, they are 8 inch and 10.1 inch Galaxy Tab 3. The configuration details of 8 inch Galaxy Tab 3 are: 1.5 GHz Exynos dual core processor WXGA TFT display screen, resolution is 1280x800 px and 189 PPI The main camera is 8 megapixel, 1.3 megapixel front camera 4450 mAh battery 1.5 GB RAM 16GB/32GB storage space The configuration details of 10.1 inch Galaxy Tab 3 are: 1.6 GHz Intel dual-core processor...

   Samsung Galaxy Tab 3,Tablet     2013-06-03 12:17:04

  MySQL index optimization

Problem description: We need to access a very big table which has 40 million records. In the table, id is the primary key and program_id is indexed. When executing a select query: select * from program_access_log where program_id between 1 and 4000 The above query executes very slowly, we thought it was because there were too many records in the table. So we added id in the where condition to limit the search so that each time only half a million records would be read. select * fr...

   MySQL,Index search, Partition     2012-12-26 13:14:20

  10 Points about Java heap memory

When I started java programming I didn't know what is java heap or what is heap space in Java, I was even not aware of where does object in Java gets created, it’s when I started doing professional programming I came across error java.lang.outofmemoryerror then I realized What is Heap in Java or Java Heap Space. Its happens with most of programmer because learning language is easy but learning basics is difficult since there is no formal process which can teach you every basics of pro...

   Java,Heap memory,Tips     2012-02-20 05:38:06

  Apple unveils iPad Mini

Apple unveiled iPad family's new product -- iPad Mini, it means that Apple gets into 7 inch tablet PC market now formally. iPad mini, has a 1024*768 resolution 7.9-inch screen, It has the same resolution as iPad 2. As a low-end product of iPad family, iPad mini still retains the front and rear camera, a dual-core A5 processor, battery life time is 10 hours. Apple said that the iPad mini battery is the thinnest and biggest in iPad family. Previously the media said the smallest storage space of iP...

   iPad mini,Price     2012-10-23 15:10:41

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