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This article focuses on "how to solve the problem of unsuccessful flock php locks". Interested friends may wish to have a look. The method introduced in this paper is simple, fast and practical. Let's let the editor take you to learn "how to solve the problem of unsuccessful flock php locks".

The flock php lock is unsuccessful because $file_lock does not continue to be used after the isRunning () method exits, and the solution is to ensure that the file handle is not released throughout the lifetime of the PHP.

This article operating environment: Windows7 system, PHP7.1 version, DELL G3 computer

What if the flock php lock is not successful?

Php flock failure resolution:

In the past two days, I have written a method for my amateur project to avoid the concurrent execution of PHP scripts scheduled by crontab.

Practice

Generally, by using the file lock flock method, the same PHP script uses a non-blocking lock on the same disk file, and an error is reported if the file is occupied, so that the script can exit immediately.

Phenomenon

However, in practice, it is found that direct flock can be implemented in controller files, and it becomes invalid when the logic of flock is encapsulated into a function in other files.

Reason

After debugging for a long time, I suddenly remembered that I had encountered this pit before. No, no, no.

The error code is as follows:

Class Crontab {/ * ensure that tasks are not executed concurrently * / public static function isRunning () {global $argv; $ident = []; foreach ($argv as $idx = > $value) {$ident [] = $idx. '='. Urlencode ($value);} $ident = md5 (implode ('&', $ident)); $lockDir =\ Yii::getAlias ('@ app/runtime/crontab/'); @ mkdir ($lockDir, 0755, true); $file_lock = fopen ($lockDir. $ident, 'wicked'); $wouldBlock = 0; flock ($file_lock, LOCK_EX | LOCK_NB, $wouldBlock); return $wouldBlock;}} class Crontab {/ * make sure the task is not executed concurrently * / public static function isRunning () {global $argv; $ident = []; foreach ($argv as $idx = > $value) {$ident [] = $idx. '='. Urlencode ($value);} $ident = md5 (implode ('&', $ident)); $lockDir =\ Yii::getAlias ('@ app/runtime/crontab/'); @ mkdir ($lockDir, 0755, true); $file_lock = fopen ($lockDir. $ident, 'wicked'); $wouldBlock = 0; flock ($file_lock, LOCK_EX | LOCK_NB, $wouldBlock); return $wouldBlock;}}

A unique hash value is generated based on the command line arguments, representing the PHP task.

Create a lock file, execute a flock non-blocking lock, and return wouldBlock to identify whether the lock is occupied.

I called the Crontab::isRunning () method on the script entry and found that when I started the script concurrently, I always got the lock.

The reason for the error is that after the isRunning () method exits, $file_lock is not in use and is garbage collected by PHP, and the closure of the $fp file handle causes the lock to be released automatically.

Solve

Class Crontab {/ * is saved to avoid being garbage collected by php * @ var null * / static $file_lock = null; / * make sure the task is not executed concurrently * / public static function isRunning () {global $argv; $ident = []; foreach ($argv as $idx = > $value) {$ident [] = $idx. '='. Urlencode ($value);} $ident = md5 (implode ('&', $ident)); $lockDir =\ Yii::getAlias ('@ app/runtime/crontab/'); @ mkdir ($lockDir, 0755, true); self::$file_lock = fopen ($lockDir. $ident, 'wicked'); $wouldBlock = 0; flock (self::$file_lock, LOCK_EX | LOCK_NB, $wouldBlock); return $wouldBlock;}} class Crontab {/ * saved to avoid being collected by php as garbage * @ var null * / static $file_lock = null / * make sure the task is not executed concurrently * / public static function isRunning () {global $argv; $ident = []; foreach ($argv as $idx = > $value) {$ident [] = $idx. '='. Urlencode ($value);} $ident = md5 (implode ('&', $ident)); $lockDir =\ Yii::getAlias ('@ app/runtime/crontab/'); @ mkdir ($lockDir, 0755, true); self::$file_lock = fopen ($lockDir. $ident, 'wicked'); $wouldBlock = 0; flock (self::$file_lock, LOCK_EX | LOCK_NB, $wouldBlock); return $wouldBlock;}}

Make sure that the file handle is not released throughout the PHP lifetime, so save it in the class static member variable.

At this point, I believe you have a deeper understanding of "how to solve the problem of unsuccessful flock php locks". You might as well do it in practice. Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

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