When the CPU usage of a MySQL database rises abnormally, it's necessary to quickly identify the problematic SQL statements. In this post, we try to provide one way to achieve this. Below are the actual steps.1. Use the top command to find the threads with the highest CPU usage in the MySQL process.# Find the MySQL process IDps -ef | grep mysql# Use the process ID to find the thread IDs with the highest CPU usage:top -H -p In top, press P to sort by CPU usage.Note the thread ID, for example, 39449.2. Log in to the database to query performance_schema and information_schema.-- Query the thr...

In Go, creating goroutines is straightforward, but improper usage may result in a large number of goroutines unable to terminate, leading to resource leakage and memory leaks over time. The key to avoiding goroutine leaks is to manage the lifecycle of goroutines properly. By exporting runtime metrics and utilizing pprof, one can detect and resolve goroutine leakage issues.This post will go through one real case encountered by the author. The author maintains a service that connects to a target machine via SSH and executes commands. This is an internal service that is usually not closely monito...

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 maintype Person struct { Name string Age int}func main() { var me Person me.Name = "Melvin" me.Age = 41 var wife Person wife.Name = "Raye" wife.Age = 36 var daughter Person daughter.Name = "Kat...

SSH is a popular cryptographic network protocol for secure network service operation. It is frequently used in remote server login. For a system administrator or software developer, SSH is frequently used to access remote servers or development servers or testing servers etc. To login with SSH, there are different authentication mechanisms : password, public key and interactive etc. If a remote server needs to be accessed frequently, password authentication may be too troublesome as password needs to be typed every time. In this scenario, public key authentication would be a life sav...

Log is a critical part of an application. It serves as an eye to the programmer on how the application is working while debugging. Especially for applications running on production environment, if the application encounters problem and the problem cannot be reproduced on other environments, log will be extremely useful.While log is essential, but developers have to log smartly. Because if don't put log smartly, you may not get what you want while debugging or you may get too many redundant logs which eat up the disk space and degrade the performance of the system.So what and wha...

It is a common task to echo messages to the user using PHP. There are lots of ways where the message can be echoed to the client terminal(browser or console window) through PHP. These includes some well know debug methods like var_dump() and var_export() etc. In this post, we will show you some other methods shared by Laruence, one of the core members of PHP development team.1. echoFirst comes with the most common one : echo.$str = "Hello PHP\n";echo $str;2. printThen comes another common one : print.$str = "Hello PHP\n";print $str;3. php://outputAlso we can use file_put_contents() t...

If you want to debug the issue of "MySQL server has gone away", you can reproduce it with below steps:Modify configuration file:sudo vi /etc/mysql/my.cnf  Make below changes:[mysqld]  wait_timeout = 30  interactive_timeout = 30  Restart the service:sudo /etc/init.d/mysql restart  Write below PHP codes:$link = mysql_connect('127.0.0.1', 'root', 'root');  if (!$link) {      die('Could not connect: ' . mysql_error());  ...

JavaScript debug is a very troublesome thing in web application development. Because many web browsers will not notify you if there is any error in the JavaScript codes you write. They just silently fail and block the following codes execution. In order to debug JavaScript codes, we need a good log mechanism which will help us log the error information,, we often need to log errors in JavaScript codes to server for debug purpose in a production web application,What should we do?The first thought comes into our mind may be using AJAX, since it involves client server communication and we al...