Understand the underlying development principles of PHP: performance optimization and debugging skills

Understand the underlying development principles of PHP: performance optimization and debugging skills

In the PHP development process, performance optimization and debugging are very important links. An in-depth understanding of the underlying development principles of PHP can help us better optimize performance and solve problems. This article will introduce some underlying PHP development principles and some commonly used performance optimization and debugging techniques, and give corresponding code examples.

1. PHP underlying development principle

1. Working principle of PHP

PHP is a server-side scripting language, which is executed on the server PHP interpreter to parse and execute PHP scripts. When the client initiates a request, the server hands the PHP file to the PHP interpreter for processing, and finally returns the processing result to the client.

2. The underlying implementation of functions and variables

In PHP, the underlying implementation of functions and variables mainly relies on hash tables. PHP uses the function name or variable name as the key of the hash table, and stores the function body or variable value as the value of the hash table. When you need to call a function or use a variable, PHP will look up and process it based on the key-value pairs in the hash table.

2. Performance optimization skills

1. Reduce the number of database queries

Database queries are one of the common performance bottlenecks in Web applications. In order to reduce the number of database queries, caching technology can be used to cache the query results in memory, and the next query will directly obtain the data from the cache. This can be achieved using distributed caching tools such as Memcached or Redis.

Sample code:

// 检查缓存中是否存在查询结果
if(memcache-> get('data')){
    // 从缓存中获取数据
    $data = memcache-> get('data');
}else{
    // 从数据库中查询数据
    $data = db-> query('SELECT * FROM table');
    // 将查询结果存入缓存
    memcache-> set('data', $data);
}

2. Reasonable use of caching technology

In addition to caching database query results, some popular calculation results can also be cached. For example, the calculated results of the first 100 Fibonacci numbers can be cached and obtained directly from the cache the next time the calculation is performed to avoid repeated calculations and improve performance.

Sample code:

function Fibonacci($n){
    if(memcache-> get('Fibonacci_'.$n)){
        return memcache-> get('Fibonacci_'.$n);
    }else{
        if($n == 0 || $n == 1){
            return $n;
        }else{
            $result = Fibonacci($n - 1) + Fibonacci($n - 2);
            memcache-> set('Fibonacci_'.$n, $result);
            return $result;
        }
    }
}

3. Avoid a large number of IO operations

IO operations (such as file reading and writing, network requests, etc.) usually consume more time. In order to avoid the impact of a large number of IO operations on performance, IO operations can be combined to reduce the number of operations. For example, if you need to write 1,000 files, you can write the data into the memory buffer first, and then write the files in batches after the data for 1,000 files is ready.

Sample code:

$buffer = '';
foreach($data as $item){
    $buffer .= $item;
    if(strlen($buffer) >= 1024 * 1024){
        // 执行批量写入操作
        file_put_contents('filename', $buffer, FILE_APPEND);
        $buffer = '';
    }
}
if(strlen($buffer) > 0){
    file_put_contents('filename', $buffer, FILE_APPEND);
}

3. Debugging skills

1. Use logging tools

In the PHP development process, use logging tools Debugging a program is a common approach. You can output key information in the program to a log file and observe the output log information to locate the problem.

Sample code:

$file = fopen('log.txt', 'a');
fwrite($file, 'debug info');
fclose($file);

2. Use breakpoint debugging tools

Breakpoint debugging is a very effective debugging method. You can use tools such as Xdebug to set breakpoints in the code. When the program reaches the breakpoint, it stops executing. You can view the execution of the code line by line and observe the values ​​of variables.

Sample code:

// 代码中设置断点
$var = 'test';
xdebug_break();
// 执行到此处时，程序将暂停执行，可以查看$var的值
echo $var;

3. Use performance analysis tools

Performance analysis tools can help us analyze the performance bottlenecks of the code and find out where the performance problems lie. . For example, you can use tools such as XHProf for performance analysis, set performance analysis points in the code, and then observe the analysis results.

Sample code:

// 设置性能分析点
xhprof_enable();
// 执行需要进行性能分析的代码
// 输出分析结果
$xhprof_data = xhprof_disable();
print_r($xhprof_data);

Summary:

By understanding the underlying development principles of PHP, we can better perform performance optimization and debugging. Reasonable use of caching technology, reducing the number of database queries, avoiding a large number of IO operations, and using techniques such as logging tools, breakpoint debugging tools, and performance analysis tools can all improve the performance and efficiency of PHP applications. I hope the content of this article can help everyone.

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