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  What is Hystrix and How does Hystrix work

Background In distributed systems, there is one effect where the unavailability of one service or some services will lead to the service unavailability of the whole system, this is called service avalanche effect. A common way to prevent service avalanche is do manual service fallback, in fact Hystrix also provides another option beside this. Definition of Service Avalanche Effect Service avalanche effect is a kind of effect where the service provider fails to provide service which causes t...

   AVALANCHE EFFECT,HYSTRIX,DISTRIBUTED SYSTEM     2019-02-04 06:00:38

  How to send asynchronous requests in PHP

It’s easy to make asynchronous calls in PHP with just a little bit of HTTP header knowledge and some library code around PHP sockets. This technique is useful when posting requests to your own server for bits of logic you’d like to run in the background.  If you don’t control the endpoint, you might not be comfortable with some of the limitations, such as the inability to read anything from the response.  So, you couldn’t post data to a we...

   PHP,Asynchronous request,socket     2012-04-28 06:45:51

  When Should Open Source Be Written Into Law?

As a systems administrator, I tend to think about source code and computing platform in large numbers. Computers however are getting smaller and more powerful, and the reality of computers that we put in or on our body as a normal daily routine is coming closer, and for many is already here. When our safety, our liberty, and our sense of humanity are tied to programmable devices, should we not only hope, but expect that we should have the right to examine how these devices function? Last ...

   Software,Open source,Time,Law     2012-01-28 07:23:09

  Tips to Keep in Mind When Adding Devices to WiFi

When it comes to powerful tools, it is hard to beat the Internet. We can use it to access a huge variety of news, information, entertainment, products and more. When the Internet first became a thing, people pretty much had to be sitting at their computers to use it. But now, thanks to the advent of a wireless network known as WiFi, you can connect to the Internet through your smartphones, streaming devices, laptops and more from anywhere in the house. If you are in the market for some new tech...

   ROUTER,TIPS,WIFI     2021-10-01 08:19:19

  Will Artificial Intelligences Find Humans Enjoyable?

Will AIs find humans interesting, enjoyable, and worthy of companionship? My guess: the smarter and more autonomous they become the more the answer will become NO. There are practical reasons for AIs to want to understand humans: The AIs will want to protect themselves from all threats, including human threads. The AIs will also want to get more resources (e.g. energy, raw materials for fabrication of additional computing power). The extent that humans control access to resources AIs will...

   AI,People,Cooperation,Enjoyable     2012-02-19 06:13:47

  Three things you should never put in your database

As I've said in a few talks, the best way to improve your systems is by first not doing "dumb things". I don't mean you or your development staff is "dumb", it's easy to overlook the implications of these types of decisions and not realize how bad they are for maintainability let alone scaling. As a consultant I see this stuff all of the time and I have yet to ever see it work out well for anyone. Images, files, and binary data Your database supports BLOBs so it must be a good idea to shove ...

   Database,BLOB,Log,Image     2012-05-02 04:44:25

  Obviously Correct

What do automatic memory management, static types and purity have in common? They are methods which take advantage of the fact that we can make programs obviously correct (for some partial definition of correctness) upon visual inspection. Code using automatic memory management is obviously correct for a class of memory bugs. Code using static types is obviously correct for a class of type bugs. Code using purity (no mutable references or side effects) isobviously c...

   Memory management,Code,Static,Purity     2011-11-07 08:13:05

  Why can System.out.println be used to exit while loop

Let's first take a look at one simple Java thread code snippet which is supposed to exit the while loop after the first loop run. public class StopThread { private static boolean stopRequested; public static void main(String[] args) throws InterruptedException { Thread backgroundThread = new Thread(new Runnable() { @Override public void run() { int i = 0; while (!stopRequested) { i++; } } }); backgroundThread.start(); TimeUnit.SECONDS.sleep(1); stopRequested = true; } } But the tr...

   JAVA,THREAD,VOLATILE     2018-12-21 19:25:54

  git reset vs git revert

When maintaining code using version control systems such as git, it is unavoidable that we need to rollback some wrong commits either due to bugs or temp code revert. In this case, rookie developers would be very nervous because they may get lost on what they should do to rollback their changes without affecting others, but to veteran developers, this is their routine work and they can show you different ways of doing that. In this post, we will introduce two major ones used frequently by develo...

   GIT,GIT RESET,GIT REVERT     2019-02-02 08:26:39

  Cache Reheating - Not to be Ignored

An important aspect to keep in mind with databases is the cost of cache reheating after a server restart. Consider the following diagram which shows several cache servers (e.g., memcached) in front of a database server.This sort of setup is common and can work quite well when appropriate; it removes read load from the database and allows more RAM to be utilized for scaling (when the database doesn’t scale horizontally). But what happens if all the cache servers restart at the same time, s...

   Database,Cost,Cache reheating,Advice     2011-09-21 09:47:29

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