Two solutions for PHP destructor method __destruct() not triggering

This article mainly introduces two solutions to the problem that the PHP destructor method __destruct() is not triggered.

Sometimes when a class is referenced cyclically in PHP, it will cause the problem that __destruct() is not triggered. First, let’s look at the problem code:

<?php
class Proxy
{
    private $object;
 
    public function __construct($object)
    {
        $this->object = $object;
    }
 
    public function __destruct()
    {
        var_dump(&#39;__destruct:Proxy&#39;);
    }
}
 
class Test
{
    private $proxy;
 
    public function __construct()
    {
        $this->proxy = new Proxy($this);
    }
 
    public function __destruct()
    {
        var_dump(&#39;__destruct:Test&#39;);
    }
}
 
$test = new Test;
unset($test);
 
echo &#39;no __destruct, wait 3s&#39;, PHP_EOL;
 
sleep(3);
 
echo &#39;__destruct now:&#39;, PHP_EOL;

As shown in the above code, when running unset($test), __destruct() will not be triggered because there is a circular reference.

Look at the code of solution 1 below:

<?php
class Proxy
{
    private $object;
 
    public function __construct($object)
    {
        $this->object = $object;
    }
 
    public function __destruct()
    {
        var_dump(&#39;__destruct:Proxy&#39;);
    }
}
 
class Test
{
    private $proxy;
 
    public function __construct()
    {
        $this->proxy = new Proxy($this);
    }
 
    public function __destruct()
    {
        var_dump(&#39;__destruct:Test&#39;);
    }
 
    public function close()
    {
        $this->proxy = null;
    }
}
 
$test = new Test;
$test->close();
 
echo &#39;__destruct now:&#39;, PHP_EOL;
 
unset($test);
 
sleep(3);
 
echo &#39;no operation&#39;, PHP_EOL;

In the above code, before unset, set the proxy in the Test class to null, and then unset again to trigger __destruct ().

Of course, you can also manually gc (solution 2):

<?php
class Proxy
{
    private $object;
 
    public function __construct($object)
    {
        $this->object = $object;
    }
 
    public function __destruct()
    {
        var_dump(&#39;__destruct:Proxy&#39;);
    }
}
 
class Test
{
    private $proxy;
 
    public function __construct()
    {
        $this->proxy = new Proxy($this);
    }
 
    public function __destruct()
    {
        var_dump(&#39;__destruct:Test&#39;);
    }
}
 
$test = new Test;
unset($test);
 
echo &#39;__destruct now:&#39;, PHP_EOL;
gc_collect_cycles();
 
sleep(3);
 
echo &#39;no operation&#39;, PHP_EOL;

I hope it will be helpful to friends in need!

The above is the detailed content of Two solutions for PHP destructor method __destruct() not triggering. For more information, please follow other related articles on the PHP Chinese website!