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  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

  Content based HTTP Cache

Browsers may cache the webpages we visited, when user types a URL on the address bar, the browser may cache the webpage returned from server while displaying it. If there is no update on the webpage, then next time when the browser requests the same page, it will not download the page again, instead it will load the cached page. If the website explicitly specify that the page is updated, then the browser will download the page again from the server. What's HTTP Cache? You may be familiar with th...

   HTTP Cache,Web crawler     2013-05-24 05:12:59

  The Pitfall of WebSocket Disconnections Caused by Browser Power-Saving Mechanisms

Preface Recently, while using WebSocket (WS) connections, we encountered frequent disconnection issues, occurring hundreds of times per day for a single user. Although using the auto-reconnect feature of socket.io allowed us to quickly restore connections after disconnections, it did not guarantee that every reconnection would successfully receive WS messages. Therefore, we conducted several investigations and tests. Ultimately, we identified the root cause of the issue: the browser's power-savi...

   WEBSOCKET,JAVASCRIPT,POWER SAVING,TROUBLESHOOTING     2024-06-23 01:19:39

  Event Loop Mechanism in JavaScript

Introduction The Event Loop Mechanism The event loop mechanism is the core of how JavaScript handles asynchronous operations. It ensures that the execution order of the code aligns with the expected sequence. JavaScript's Single Thread JavaScript is known for being a single-threaded language, meaning it executes one task at a time. This can lead to a significant issue: if a thread is blocked, the entire program becomes unresponsive. To address this, JavaScript introduced the event loop mechanism...

   JAVASCRIPT,EVENT MECHANISM,EVENT LOOP     2024-07-03 08:19:09

  Set PHP session timeout

There are many different discussions about PHP sessions. We may often face some weird issues while handling PHP sessions. Sometimes session is expired earlier than expected. Or sometimes the session is not expired. This introduces many confusions. Today we discuss how to set PHP session timeout correctly today. In php.ini, there are three key parameters which will affect the session timeout. session.gc_maxlifetime, session.gc_probability and session.gc_divisor. session.gc_maxlifetime defined the...

   PHP,session,timeout     2013-08-31 08:11:03

  Singleton Pattern in Golang

Singleton pattern is the simplest design pattern in software design. It ensures that only one instance of an object exists globally, regardless of how many times the object is instantiated. Based on the characteristics of the singleton pattern, it can be applied to scenarios such as global unique configuration, database connection objects, file access objects, etc. In Go language, there are multiple ways to implement the singleton pattern. Today, let's learn together about some of these approach...

   GOLANG,SINGLETON PATTERN,TUTORIAL     2023-08-18 23:52:05

  What you may not know about PHP session

When we access one website, the site usually should have a mechanism to keep track of the status of the user on the site. There are a few mechanisms supported by many server side languages to help track user status such as session and cookie. Today we will talk about session, when creating a session, we need to keep track of many data, besides user data, we also need to tell the server what is the timeout of the session so that we can garbage collect the session data which should not be stored a...

   PHP session,session timeout,example     2013-07-06 08:44:18

  How to check whether a struct implements an interface in GoLang

Unlike other programming languages like Java, when implementing an interface in GoLang, there is no syntax like below to explicit tell the relationship: type I interface { } type A struct implements I { } When looking at the code or running the code in GoLang, it might lead to a case one doesn't know whether a struct implements interface before trying to use it as some interface. According to GoLang spec, as long as a struct implements all functions of an interface, it is considered as having i...

   GOLANG,INTERFACE,IMPLEMENTATION,CHECK     2020-05-03 00:05:54

  Introduction to DTLS(Datagram Transport Layer Security)

Secure communication has become a vital requirement on the Internet. Lots of information transferred through the Internet are sensitive data such as financial transactions, medical information, media streaming etc. To ensure security of data transferred on the Internet, a few secure protocols have been designed including SSL/TLS and IPsec. Many large websites in the world have adopted TLS. Apart from SSL/TLS, there is some other protocol designed to be used in special cases. One of them is ...

   JAVA 9,DTLS,TLS,SECURITY     2016-04-02 05:55:36

  Deep Dive into Spin Locks in Golang

In concurrent programming, a Mutex is a commonly used synchronization mechanism to protect critical resources and prevent data races. However, in certain specific scenarios, especially when the lock-holding time is short and the number of threads is limited, a more lightweight lock known as a Spin Lock can provide higher performance. What is a Spin Lock A Spin Lock is a form of busy-wait lock. When a thread attempts to acquire a lock held by another thread, it continuously checks the lock's stat...

   SPINLOCK,MUTEX,GOLANG     2024-01-10 05:53:28

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