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  Service discovery with etcd

In previous post, we have talked about etcd and its usage. This post we will cover how to implement server discovery with etcd. Service discovery is to solve one of the most commonly seen scenarios in distributed system where how to find the corresponding target service to talk to. In short, it is to find some server which one can talk to based on some service name. A complete service discovery system include below three key functions: Service registration: A service must register itself to so...

   ETCD,SERVICE DISCOVERY,DEMO,TUTORIAL     2021-03-08 05:36:29

  Difference between ConcurrentHashMap and Hashtable

Both ConcurrentHashMap and Hashtable are Collection classes for storing key value pairs and they both provide fast element search with a supplied key. They have much in common. However, we will not discuss the similarities between them here, instead we will focus on the differences between them. ConcurrentHashMap and Hashtable are both thread safe. But the mechanism for thread safe is different between them. Hashtable is synchronized, it utilizes the synchronization mechanism; while ConcurrentHa...

   ConcurrentHashMap,Hashtable     2013-11-18 08:06:54

  Simple explanation about process and thread

Process and thread are two basic concepts of operating system, but they are a bit abstract which cannot be  mastered easily. There is an analogy which explains these concepts very well. 1. The kernel of the computer is CPU, it handles all the computing tasks, it's like a factory and will run all the time. 2. Assume there is power limitation for the factory, it can only supply to one unit once,i.e, when one unit is working, other units must stop and wait. The meaning behind this is that eac...

   Process,Thread,CPU,Operating system     2013-04-24 11:33:10

  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

  10 major updates of Windows 8.1

Last night, the 2013 Microsoft Build Developer Conference started in San Francisco. The highlight of the first day is Microsoft CEO Steve Ballmer announced the release of Windows 8.1 Preview . The final version will be released in November and he also mentioned that there would be over 300 updates on the new OS. Now let's summarize 10 major updates of the new OS. 1. Classical desktop mode After getting a lot of feedback from users, Microsoft adds a new setting. Users can choose to start in clas...

   Windows 8.1,Build     2013-06-27 05:45:02

  Recursive class initialization in Java

When a Java class is referenced and initialized, it has to go through the loading and linking first. Once the loading and linking complete successfully. The class will be initialized. The static variables and constant variables will be initialized during this process. Once the class is initialized, it is ready for use. If when class A is initialized and it is referencing a class B, the class B will also get initialized. But what will happen if class B is referencing class A as well? This is call...

   Java,JVM,class initialization,static final     2015-04-15 21:04:29

  Simple Strategies to Boost Your Android Phone Security

Android is one of the safest operating systems for smartphones and tablets if used correctly. Unfortunately, only a third of Android users use the latest version, and older versions are far more vulnerable than newer ones. Not to mention that many manufacturers take their time when it comes to downloading the latest security patches. A news blog Android Authority ranked the fastest manufacturers in downloading system updates. Here are the results: LG - 78 days Motorola - 88 days HTC - 95 days S...

   ANDROID,DATA SECURITY     2019-02-19 07:36:46

  Why init() is not recommended in Go

golangci lint Currently, the unified CI's .golangci.yml includes the gochecknoinits checker: # golangci-lint v1.46.2 # https://golangci-lint.run/usage/linters linters: disable-all: true enable: ... - gochecknoinits # Checks that no init functions are present in Go code. ref: https://github.com/leighmcculloch/gochecknoinits ... If Go code uses the init() function, the following error will occur: # golangci-lint run foo/foo.go:3:1: don't use `init` function (gochecknoinits) func i...

   GOLANG,INIT(),SYNC.ONCE,PANIC     2024-05-10 07:46:18

  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

  C++ and Java over Python in Google products

In Google, most of the products are written in C++ and Java. They usually don't choose Python to write their product stack. What's behind the decision to choose one language over the other in Google? Let's get to read some opinions from Robert Love, a Google software engineer. Love said he couldn't imagine writing let alone maintaining a large software stack in Python. They use C++, Go, and Java for production software systems, with Python employed for scripting, testing, and tooling.There are a...

   Java,Python,Google     2014-07-20 04:39:09

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