How to implement scheduled tasks in PHP to better complete background processing

With the continuous development of Internet business, the number of background processing tasks is also increasing. In order to better handle these tasks, PHP also needs to be able to implement the function of scheduled tasks. This article will introduce how to implement scheduled tasks in PHP and how to better complete background processing tasks.

1. What is a scheduled task

A scheduled task refers to executing a specified task at a specified time, which can be one-time or periodic. In back-end task processing, it is often necessary to execute a function regularly or send emails regularly, etc.

2. How to implement scheduled tasks in PHP

1. Cron expression

To implement scheduled tasks in PHP, Cron expression is generally used, which is a A special syntax used to indicate when to perform a task. The syntax of a Cron expression is composed of 6 or 7 fields (seconds, minutes, hours, days, months, weeks, years), each field is separated by spaces.

For example, the following is a Cron expression:

* 0/15 10,18 * * ?

This expression means : Execute tasks at the 0th and 15th minutes at 10 am and 6 pm every day.

2. Scheduled tasks

PHP itself does not have a built-in scheduled task function, but it can be implemented through the scheduled tasks of the operating system. In Linux systems, you can use the crontab command to configure scheduled tasks.

For example, to execute a PHP script file.php at 10 o'clock every day, you can create a scheduled task through the following command:

crontab -e

Then add the following line:

0 10 * * * php /path/to/file.php

Each field in this line of command represents: minutes (0), hour (10), day (), month (), and week (*) are all arbitrary values, indicating execution at 10 o'clock every day. The last php /path/to/file.php represents the PHP script file to be executed.

3. Third-party packages

In addition to using the scheduled tasks of the operating system, there are many PHP third-party packages that can implement the function of scheduled tasks. For example, PHP's swoole extension can easily implement timer tasks.

The following is an example:

$serv = new SwooleHttpServer("127.0.0.1", 9501);

$serv->on('WorkerStart', function($serv, $worker_id) {
    if ($worker_id == 0) {
        // 每隔10秒执行一次
        swoole_timer_tick(10000, function() {
            //todo
        });
    }
});

$serv->start();

This code can implement a scheduled task that is executed every 10 seconds, and the tasks that need to be processed can be performed in the callback function.

3. How to better complete background processing tasks

1. Multi-threading

In background task processing, a large amount of data may need to be processed , the processing time is also very long. If multiple tasks are independent of each other, you can consider using multi-threading to improve task processing efficiency.

PHP itself is a single-threaded language, but we can use the PCNTL library or swoole extension to implement multi-process.

2. Asynchronous processing

In background processing tasks, many operations are I/O operations, such as sending emails, database queries, etc. These operations will block threads and cause tasks to Processing efficiency is reduced.

In order to avoid this problem, you can use asynchronous processing. You can use third-party libraries such as swoole and ReactPHP to implement asynchronous processing.

3. Queue

When processing tasks, if you need to execute them sequentially according to certain rules, you can consider using a queue. For example, if there is a batch of emails that need to be sent, you can put the emails in the queue and then take them out one by one for sending.

Common queue libraries include Redis, Beanstalkd, etc.

4. Summary

This article introduces how PHP implements scheduled tasks and how to better complete background processing tasks. The efficiency and stability of background task processing can be improved by using scheduled tasks, third-party packages, multi-threading, asynchronous processing and queues.

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