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  Use rsync to delete mass files quickly in Linux

Yesterday I encountered an issue to delete many log files in my Linux workstation, there were around 100,000 files to be deleted. These are log files and they grow very fast, and we need to delete them frequently. Usually we would use rm -rf * to delete these files, but we may need to wait for a relative long time if there are too many files. So we must adopt some unusual way. Fortunately, we can use rsync to delete mass files in one shot. 1. Install rsync yum install rsync 2. Create a new empty...

   rsync,delete file, demo     2012-11-13 10:44:50

  A mini post on GoLang context

In a GoLang web server, every request coming in will be handled by a goroutine. In the request handler, the logic may also need to create new goroutine to handle other tasks like RPC call. When the request is processed and response is returned, these goroutines created need to be exited so that no goroutine leak should happen. package main import ( "fmt" "log" "net/http" ) func main() { http.HandleFunc("/echo", func(w http.ResponseWriter, r *http.Request) { fmt.Println(&r) w.Write(...

   CONTEXT,GOLANG     2019-12-14 06:21:02

  Use Delve to debug GoLang program

If you don't know how to debug program, you are not a real programmer. gdb can be used to debug go program, but according to golang website, delve is a better option.   Note that Delve is a better alternative to GDB when debugging Go programs built with the standard toolchain. It understands the Go runtime, data structures, and expressions better than GDB. Below is a simple go program. package main type Person struct { Name string Age int } func main() { var me Person me.Nam...

   GOLANG,DEBUG,DELVE     2018-11-09 23:28:43

  How to make select in WinSock exceed the 64-socket limit

When doing cross-platform network programming, the only API available on Windows that corresponds to the epoll/kevent style reactor event model is select. However, it has a limitation: the number of sockets passed into select cannot exceed FD_SETSIZE, which is set to 64. Therefore, select in Java’s NIO on Windows also has the same limit. Many services ported to Windows that use the reactor model face this constraint, which often gives the impression that server programs on Windows hav...

   EXCEED,SELECT,JAVA,WINDOWS     2024-10-31 23:47:50

  How to commit code to OpenStack

If you want to make contributions to OpenStack, the best way to start is to help the community with blueprint or submit bug fix. To commit codes, you need to conform to some rules in the community. Work flow Register an OpenID Apply for a CLA certificate Apply for company CLA certificate Update contributor list Join OpenStack Contributors group and OpenStack group Set up SSH Keys Get a blueprint/bug git clone codes to local disk. Configure user name and user email and openid Modify codes in a l...

   OpenStack,Contribution     2013-08-04 23:04:45

  The First Bite on etcd Code

Etcd, one of the crucial components of Kubernetes. If APIServer is the heart, then etcd is the blood vessel that sends the end state of Kubernetes resources to various “organs”, providing high-speed, stable storage, and supporting APIServer’s high load performance. What if the etcd is not working properly? Just the condition as someone has a vascular disease. The deeper you know about them, the better diagnose you can make when issues occur. from unspl...

   SOURCE CODE,ETCD     2022-02-12 01:03:14

  String intern in Java

In Java, == is used to compare whether two objects have the same memory location, equals() is usually used to compare whether two objects have the same time and the same state.  When comparing two strings, normally we just want to know whether they have same content, so we can choose equals(). But since String comparison is so frequently needed, Java has worked on the String class to make == workable when comparing two String literals. The String class maintains a pool of emp...

   JAVA,STRING     2016-04-10 03:35:25

  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

  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

  New features in PHP 5.5

Just a few days ago, the PHP official website was redesigned. It seems we directly go from Web 1.0 era to Web 2.0 era. In addition to this new change, PHP 5.5 was also released. Some new features are added in this release. Here we summarize some of them. Enable OPCache by default When installing PHP 5.5, the Zend OPCache will be compiled as OPCache by default and OPCache is enabled by default. Some changes to the language itself Add Generator function getLinesFromFile($fileName) { if (!$file...

   PHP 5.5,New features,Generator     2013-07-05 03:13:22

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