


PHP automatically generates thumbnails based on URLs and handles high concurrency issues_PHP tutorial
There are generally two types of timing for the server to generate thumbnails: generated when uploading files and generated when accessing. Here is an introduction to how PHP automatically generates thumbnails based on URLs and handles high concurrency issues
The timing for the server to generate thumbnails is generally divided into two types: 1. Generated when uploading files Advantages: The required thumbnails are already generated when uploading, and there is no need to judge when reading, reducing CPU operations. Disadvantage: When the thumbnail size changes or a new size is added, all thumbnails need to be regenerated. 2. Generated during access Advantages: 1. It only needs to be generated when a user accesses it. If there is no access, it does not need to be generated, which saves space. 2. When modifying the thumbnail size, you only need to modify the settings without regenerating all thumbnails. Disadvantages: When thumbnails do not exist and need to be generated, high concurrent access will consume a lot of server resources. Although there will be high concurrency problems when accessing, other advantages are better than the first method, so as long as the high concurrency problems are solved. Regarding the principle and implementation of how to automatically generate thumbnails based on URLs, you can refer to the "php automatically generates thumbnails based on URLs" I wrote before. High concurrency processing principle: 1. When it is determined that a picture needs to be generated, create a temporary mark file in the tmp/ directory. The file name is named md5 (the file name to be generated), and the temporary file is deleted after the processing is completed. 2. When it is judged that the file to be generated has a temporary mark file in the tmp/ directory, which means that the file is being processed, the thumbnail generation method will not be called, but will wait until the temporary mark file is deleted and the successful output is generated. The modified files are as follows, others are the same as before. createthumb.php The code is as follows: $wait_timeout){ // timeout exit(); } usleep(300000); // sleep 300 ms } if(file_exists($dest)){ // Image generated successfully ob_clean(); header('content-type:'.mime_content_type($dest)); exit(file_get_contents($dest)); }else{ exit(); // Exit if generation fails } } //Create thumbnail $obj = new PicThumb($logfile); $obj->set_config($config); $create_flag = $obj->create_thumb($source, $dest); unlink($processing_flag); // Delete the processing flag file if($create_flag){ // Determine whether the generation is successful ob_clean(); header('content-type:'.mime_content_type($dest)); exit(file_get_contents($dest)); } ?>
What’s still popular is the ease of use, flexibility and a strong ecosystem. 1) Ease of use and simple syntax make it the first choice for beginners. 2) Closely integrated with web development, excellent interaction with HTTP requests and database. 3) The huge ecosystem provides a wealth of tools and libraries. 4) Active community and open source nature adapts them to new needs and technology trends.

PHP and Python are both high-level programming languages that are widely used in web development, data processing and automation tasks. 1.PHP is often used to build dynamic websites and content management systems, while Python is often used to build web frameworks and data science. 2.PHP uses echo to output content, Python uses print. 3. Both support object-oriented programming, but the syntax and keywords are different. 4. PHP supports weak type conversion, while Python is more stringent. 5. PHP performance optimization includes using OPcache and asynchronous programming, while Python uses cProfile and asynchronous programming.

PHP is mainly procedural programming, but also supports object-oriented programming (OOP); Python supports a variety of paradigms, including OOP, functional and procedural programming. PHP is suitable for web development, and Python is suitable for a variety of applications such as data analysis and machine learning.

PHP originated in 1994 and was developed by RasmusLerdorf. It was originally used to track website visitors and gradually evolved into a server-side scripting language and was widely used in web development. Python was developed by Guidovan Rossum in the late 1980s and was first released in 1991. It emphasizes code readability and simplicity, and is suitable for scientific computing, data analysis and other fields.

PHP is suitable for web development and rapid prototyping, and Python is suitable for data science and machine learning. 1.PHP is used for dynamic web development, with simple syntax and suitable for rapid development. 2. Python has concise syntax, is suitable for multiple fields, and has a strong library ecosystem.

PHP remains important in the modernization process because it supports a large number of websites and applications and adapts to development needs through frameworks. 1.PHP7 improves performance and introduces new features. 2. Modern frameworks such as Laravel, Symfony and CodeIgniter simplify development and improve code quality. 3. Performance optimization and best practices further improve application efficiency.

PHPhassignificantlyimpactedwebdevelopmentandextendsbeyondit.1)ItpowersmajorplatformslikeWordPressandexcelsindatabaseinteractions.2)PHP'sadaptabilityallowsittoscaleforlargeapplicationsusingframeworkslikeLaravel.3)Beyondweb,PHPisusedincommand-linescrip

PHP type prompts to improve code quality and readability. 1) Scalar type tips: Since PHP7.0, basic data types are allowed to be specified in function parameters, such as int, float, etc. 2) Return type prompt: Ensure the consistency of the function return value type. 3) Union type prompt: Since PHP8.0, multiple types are allowed to be specified in function parameters or return values. 4) Nullable type prompt: Allows to include null values and handle functions that may return null values.


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