PHP asynchronous operation principle and implementation

1. Why does PHP need asynchronous operations?

Generally speaking, PHP is suitable for short-term tasks such as web page display. If you perform time-consuming operations such as resizing images, importing big data, sending EDM, SMS, etc. in batches, it is easy for operation timeouts to occur. . You can say that I can set an infinite timeout, etc. You also need to know that PHP has a working mode which is fastcgi. PHP does not timeout indefinitely, which does not mean that fastcgi will not timeout... If you still want fastcgi to never timeout, I It is recommended that you discuss it with your operation and maintenance personnel...

At this time, the asynchronous operation comes into play. Since it is a non-blocking operation, the operation will return immediately, and then work slowly in the background. It doesn’t matter whether it times out or not, I’m not working under the current process/thread. Look, isn't it wonderful, but actually it's also a pitfall...

2. Can PHP implement asynchronous operations?

The answer is yes, but various pure PHP implementations on the Internet are a bit awkward. Socket mode, suspended process mode, and some even directly fork the process. Very good, all kinds of gods show their magical powers. If the operation and maintenance personnel see it, they will definitely ××××× you. It would be strange if the web server is not killed...

Is there any other better way to achieve this asynchronous operation? Yes, now we only have to think about how to enable plug-ins. Check the mainstream plug-in solutions of PECL. There are a bunch of ××MQ (message queue). Among them, there is a plug-in for task distribution that comes into our sight. Gearman (actually this guy is the corner, I won’t introduce it in detail, click to connect See introduction).

3. Why choose Gearman?

If nothing else, just say that it has many clients and supports clients in many languages. You can use most of your favorite languages ​​to write workers. Personally, I am very annoyed by the language debate. You can use Shenma to write workers as you like. There is data persistence support (that is, the queue is saved to the database medium, so failure recovery is easy), and there is cluster support (in fact, many ××MQ have these functions). There are extensions on PECL, and there are also extensions implemented in pure PHP. Anyway, this Gearman has lived for a long time, and all the miscellaneous problems have been basically solved.

4. Basic idea

With the Gearman plug-in, it is much simpler. It means sending a task to gearman, sending out the executed task, and then waiting for the worker to call the PHP cli to run our php code.

I just wrote a python worker (don’t ask me why I use python, 1. I know python, 2. I don’t need to install runtime under Linux). You can write a PHP worker based on your own ideas, but well, I I don’t really trust workers running PHP. For other languages, you can try implementing a worker using java, node.js or other languages. Friends who are interested in writing workers in Golang can contact me.

phpasync_worker_py

Sorry, there are no comments in it. A configuration file and a py script. The basic function is to analyze the calling parameters and then call the PHP Cli, that's it. To make the py script run, please install the python gearman module yourself.

Then go to the PHP part and start the test code:

<?php 
require_once &#39;PHPAsyncClient.php&#39;; 
date_default_timezone_set(&#39;Asia/Shanghai&#39;); 
 
class AsyncTest { 
 
    const
        LOG_FILE = &#39;/debug.log&#39;; 
 
    static public function run() { 
        if (PHPAsyncClient::in_callback(__FILE__)) { 
            self::log(&#39;php Async callback&#39;); 
            PHPAsyncClient::parse(); 
            return; 
        } 
        if (PHPAsyncClient::is_main(__FILE__)) { 
            self::log(&#39;main run&#39;); 
            $async_call = PHPAsyncClient::getInstance(); 
            $async_call->AsyncCall(&#39;AsyncTest&#39;, &#39;callback&#39;, array( 
                &#39;content&#39; => &#39;Hello World!!!&#39;, 
            ), array( 
                &#39;class&#39; => &#39;AsyncTest&#39;, 
                &#39;method&#39; => &#39;callback&#39;, 
                &#39;params&#39; => array( 
                    &#39;content&#39; => &#39;Hello Callback!&#39;, 
                ), 
            ), __FILE__); 
            return; 
        } 
    } 
 
    static public function callback($args) { 
        self::log(&#39;AsyncTest callback run&#39;); 
        self::log(&#39;AsyncTest callback args:&#39;.print_r($args, true)); 
    } 
 
    static public function log($content) { 
        $fullname = dirname(__FILE__).self::LOG_FILE; 
        $content = date(&#39;[Y-m-d H:i:s]&#39;).$content."\n"; 
        file_put_contents($fullname, $content, FILE_APPEND); 
    } 
} 
 
AsyncTest::run();

There are only 3 static methods, one is the log method for debugging, and the others are literal. This example is a preliminary impression of this calling method. Then directly upload all the source code of PHP:

php_async.zip

Then many people may say that gearman cannot be installed under win... So I will also put the java version of gearman server.

java-gearman-service-0.6.6.zip

5. Conclusion

After configuring something as big as a rhinoceros (a Gearman needs to be installed and a Py script needs to be run), we have basically enabled PHP to have an asynchronous calling function. Of course, there is also a state maintenance thing that needs to be implemented by ourselves. . So I found that this solution is actually not good and too complicated. It would be better to use some web service methods to make web callbacks (the problem is that web callbacks will also time out...), please pay attention to the follow-up.