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  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

  Use CSS calc to align an element vertically

calc function is a function introduced in CSS3, it can be used to calculate length values. There are a few good features which make it suitable for aligning an element vertically. One good part is that the operands can have different units like percentage, px, rem etc. This makes it very flexible when calculating the length value. One example: .rect{ margin-top:20px; height:50px; background:green; width:calc(100%-20px); } Here the left operand uses percentage while the right one ...

   CSS3,CALC,VERTICAL ALIGN     2019-08-23 20:30:23

  How many bytes a boolean value takes in Java?

Have you ever wondered how many bytes a boolean value takes in Java? One byte, this might be the answer comes out of your mind right away. But is it? Let's dig in more. Per Oracle documentation on boolean value definition, there is below statement: boolean: The boolean data type has only two possible values: true and false. Use this data type for simple flags that track true/false conditions. This data type represents one bit of information, but its "size" isn't something that's precisely defin...

   JAVA,INTERVIEW,SIZE,BOOLEAN     2020-02-29 02:49:18

  How does GoLang know how many CPUs to use?

When running lscpu command on Linux, it will list the CPU info on the machine. Take one example where there is one CPU with 2 cores and each core has two threads which indicates there are 4 cores available. Now let's see how many cores GoLang program would identify. From output, NumCPU and GOMAXPROCS both output 4 which is expected. How does go runtime get this info, does it get it through similar command like lscpu or /proc/cpuinfo? Let's dig more in GoLang's source code. In runtim...

   GOLANG,CPU,NCPU     2020-12-29 23:22:15

  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

  Ways to undo wrong Git operations

While using Git to version code, programmers would inevitably perform some invalid operations which are not expected. Sometimes it's difficult to deal with this kind of awkward situations. If the programmer chooses to undo the operation, the programmer needs to bear the risk of deleting something which is not supposed to be deleted if the undo is done improperly. If the programmer leaves it as is, the file needs to be updated again manually with a new commit. In this post, we will try to pr...

   GIT,GIT COMMIT,GIT RESET     2018-07-07 03:28:21

  Mac shortcut key cheatsheet

More and more people are using Mac computers or switch from Windows or other OS to MacOS, there are lots of shortcut keys which can help improve the work efficiency or ease operations. This post will try to list some commonly used shortcut keys in Mac. But before that, let's first know some common keys on a Mac computer keyboard. There are four major function keys: Command, Control, Option and Shift. Most of the shortcut keys will combine the functional key and other key. Basic Command key is t...

   SHORTCUT,SCREENSHOT,COMMAND,SHORTCUT KEY,MACOS     2019-02-05 07:13:06

  The details and analysis of capturing gRPC packets

Introduction If you're only using gRPC at the application layer, I believe studying the examples on the gRPC official website is sufficient. However, when planning to extensively use gRPC within a team, you will face many challenges, such as authentication schemes between services, routing solutions for multi-region services, and compatibility solutions with existing RESTful services. I recently realized that applying a technology stack requires mastering a wealth of information about that stack...

   GRPC,GOOGLE     2024-01-14 05:59:13

  When will resizing be triggered in Java HashMap?

HashMap is one of the most frequently used collection types in Java, it stores key-value pairs. Ideally it expects to use hash table which expects the data access time complexity to be O(1), however, due to hash conflicts, in reality, it uses linked list or red-black tree to store data which makes the worst case time complexity to be O(logn).  Although collections are using data structures like arrays and linked lists, unlike arrays, they will dynamically resize when there is not enough spa...

   JAVA,RESIZE,HASHMAP,THRESHOLD     2020-05-02 20:41:19

  Understanding GoLang interface

If goroutine and channel are considered as the foundation for GoLang concurrency, interface would be the key for data types in GoLang. In practical Go programming, almost all data types are built/used around interfaces, interface is the core of GoLang data structures. Go is not a typical OOP language, it has no class and inheritance concept syntactically. But it doesn't mean that there cannot be polymorphism in GoLang. Because of interface, it achieves the same polymorphism effect as in C++, tho...

   INTERFACE,GOLANG     2021-05-15 04:16:42

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