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  Practice of using spinlock instead of mutex

Spinlock and mutex are two important concepts in multithreading programs. They are used to lock some shared resource to prevent concurrent access which may affect data consistency. But they do have differences, what are the differences? when should we use spinlock instead of mutex? The Theory In theory, when a thread tries to lock a mutex and it does not succeed, because the mutex is already locked, it will go to sleep, immediately allowing another thread to run. It will continue to sleep until...

   Spinlock,Mutex,Concurrency     2014-04-19 21:54:12

  Books for entry level C programmers

In computing, C is a general-purpose programming language initially developed by Dennis Ritchie between 1969 and 1973 at Bell Labs Its design provides constructs that map efficiently to typical machine instructions, and therefore it found lasting use in applications that had formerly been coded in assembly language, most notably system software like the Unix computer operating system.To learn C, we need to read many C books and have many practices. Here we summarize a list of C books which may h...

   C,Book,Beginning     2012-07-26 14:00:51

  Different module types in Java 9

Java 9 is going to introduce a disruptive change to the Java platform -- Module System. The module system will change how Java applications work in the future. It's like changing the foundation of a house without impacting the house functionality and its top level structure. This obviously is a big challenge for the whole Java community.  To bring as little pain as possible to migrate existing applications to Java 9 without refactoring the whole application, Java 9 will introduce a few diff...

   JAVA,JAVA 9,JIGSAW,MODULE SYSTEM,UNNAMED MODULE,AUTOMATIC MODULE,NAMED MODULE     2016-04-15 07:15:23

  My frequently used Linux commands

In our day to day work. We may have many chances working on Linux/Unix systems. There are many things we may need to do, checking logs, navigating in directories, creating file or installing software. We may use many commands to complete the work, such as ls, mkdir, cd etc. Below are my frequently used Linux commands or programs recently: pwd : print working directory, sometimes I need to check which working directory I am in in order to know where to go next. ls : List current directory files,...

   Linux,Command,Program     2012-08-16 15:09:42

  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

  Forgotten TODOs: ideas for contributing to open-source projects

I often talk to students that want to contribute to open-source projects, but just don't have an idea what to work on. Here's a tip if you're in a similar situation (e.g. you want to apply for GSOC) : 1 git clone repository_url_of_some_open_source_project target_directory 2 grep -RIn TODO target_directory/* So, find the URL of the repository project you want to contribute to, checkout the repository using git/mercurial/svn and then find all the TODOs in the source code using grep. The -RI...

   Open source,constribution,TODO,participation     2012-03-03 22:30:28

  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

  ByteBuffer in Java

ByteBuffer is introduced in java.nio since Java 1.4. It provides a way of representing raw structured data such as from a file or from network. It enables fast access of underlying data compared to traditional ways like byte[] Prior to Java 1.4, if you want to represent a structured raw data, you need to create a byte[] and then having a set of checks to delimit the byte array to get the expected tokens. There are three ways to create a ByteBuffer: Wrapping an exiting array by calling ByteBuffe...

   JAVA,BYTEBUFFER,ALLOCATION     2015-07-08 03:17:44

  Why to opt for Hadoop?

Hadoop is a open source that stores and processes big data. The framework is written in Java for distributed processing and distributed storage of very large data. Hadoop is Scalable. It is a scalable platform because it stores and distributed large amount of data sets to hundreds and thousands of servers that operate in parallel. Traditional database systems cannot process large amount of data. But, hadoop enable business to run applications involving thousands of Terabyte data. Hadoop is ...

       2015-09-22 10:17:43

  Set file permission in Java

Prior to Java 6,  there is no good solution at the Java level to provide file permission management. You need to implement your own native methods or call the Runtime.exec() to invoke the system routine such as chmod in LInux. Since Java 6, Java introduces a set of methods which can be used to set the file permission at Java level. These methods include: File.setReadable(boolean); File.setWritable(boolean); FIle.setExecutable(boolean); File.setReadable(boolean, boolean); File.setWritable(bo...

   JAVA, FILE PERMISSION, POSIX,learnjava     2015-08-29 03:37:37

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