PHP underlying kernel debugging skills and practical tools

PHP's underlying kernel debugging skills and practical tools

Introduction: PHP is a widely used scripting language. As a dynamic language, the debugging of its underlying kernel has always been The focus of developers. This article will introduce some techniques and practical tools for PHP underlying kernel debugging, and provide specific code examples.

1. Debugging skills

1. Use the var_dump() function: The var_dump() function is one of the most commonly used debugging tools in PHP. It can output the type and value of variables. When debugging the underlying PHP kernel, you can use the var_dump() function to print out the internal structure of variables to better understand and locate problems. For example:

$a = 5;
$b = "hello";
var_dump($a, $b);

Output:

int(5)
string(5) "hello"

2. Enable error log: When debugging the underlying PHP kernel, you will often encounter some errors or warning messages. In order to better locate the problem, you can set the path of the error log in the php.ini file and write the error information to the log file. For example:

error_reporting = E_ALL
log_errors = On
error_log = /path/to/error_log

3. Use xdebug extension: xdebug is one of the most commonly used debugging tools in PHP. It provides many convenient debugging functions, such as breakpoint debugging, remote debugging, etc. Using the xdebug extension can make PHP underlying kernel debugging more convenient. For example, you can add a breakpoint in the code:

$a = 5;
$b = "hello";
xdebug_break();
$c = $a + $b;

When xdebug is enabled, when the program executes xdebug_break(), it will enter the breakpoint debugging mode, and you can view the values ​​of variables, Call stack and other information.

2. Practical Tools

1. PHP kernel source code: PHP kernel source code is an essential tool for debugging the underlying PHP kernel. By reading and understanding the PHP kernel source code, you can have a deeper understanding of PHP's operating mechanism and internal implementation.
2. GDB tool: GDB is a powerful debugging tool that can be used for debugging C language and C language. For debugging of the underlying PHP kernel, GDB can be used to observe the values ​​of variables, call stacks and other information, and perform breakpoint debugging. For example, you can use the following command for breakpoint debugging:

gdb php
(gdb) break filename:line
(gdb) run

3. Valgrind tool: Valgrind is a memory debugging and performance analysis tool that can detect memory leaks, access out-of-bounds and other issues. For debugging the underlying PHP kernel, Valgrind can locate memory-related issues and provide detailed reports. For example, you can use the following command for memory detection:

valgrind --leak-check=full php script.php

3. Code example

The following is a simple code example that demonstrates using the var_dump() function and the xdebug extension for PHP Methods for underlying kernel debugging:

$a = 5;
$b = "hello";
var_dump($a, $b);

xdebug_break();

$c = $a + $b;
var_dump($c);

The value and type of variables can be printed through the var_dump() function, breakpoints can be set through xdebug_break(), and the debugger can be used to view variable values, call stacks and other information.

Summary:

This article introduces some techniques and practical tools for PHP low-level kernel debugging, including using the var_dump() function, enabling error logs, using xdebug extensions, reading PHP kernel source code, and using GDB tools and Valgrind tools etc. I hope these tips and tools can help developers better debug the underlying PHP kernel and improve development efficiency.

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