Why am I getting memory leaks in SimplePie when using $item->get_permalink()?

Question

I'm using SimplePie with PHP 5.3 (with gc enabled) to parse my RSS feeds. This works well and without problems when doing something like the following:

$simplePie = new SimplePie();
$simplePie->set_feed_url($rssURL);
$simplePie->enable_cache(false);
$simplePie->set_max_checked_feeds(10);
$simplePie->set_item_limit(0);
$simplePie->init();
$simplePie->handle_content_type();

foreach ($simplePie->get_items() as $key => $item) {
    $item->get_date("Y-m-d H:i:s");
    $item->get_id();
    $item->get_title();
    $item->get_content();
    $item->get_description();
    $item->get_category();
}

Memory debugging over 100 iterations (with different RSS feeds):

But when using $item->get_permalink(), my memory debugging looks like this over 100 iterations (with different RSS feeds).

Code to produce problem:

foreach ($simplePie->get_items() as $key => $item) {
    $item->get_date("Y-m-d H:i:s");
    $item->get_id();
    $item->get_title();
    $item->get_permalink(); //This creates a memory leak
    $item->get_content();
    $item->get_description();
    $item->get_category();
}

Things I've tried:

• Using get_link instead of get_permalink
• Using __destroy as mentioned here (even though it should be fixed for 5.3)

Current debugging process:

I seem to have traced the problem down to SimplePie_Item::get_permalink -> SimplePie_Item::get_link -> SimplePie_Item::get_links -> SimplePie_Item::sanitize -> SimplePie::sanitize -> SimplePie_Sanitize::sanitize -> SimplePie_Registry::call -> SimplePie_IRI::absolutize as of now.

What can I do to fix this?

Answer 1

This is actually not a memory leak, but rather static function caches that aren't being cleaned!

This is due to SimplePie_IRI::set_iri (and set_authority, and set_path). They set a static $cache variable, but they don't unset or clean this when a new instance of SimplePie is created, which means the variables only gets bigger and bigger.

This can be fixed by changing

public function set_authority($authority)
{
    static $cache;

    if (!$cache)
        $cache = array();

    /* etc */

to

public function set_authority($authority, $clear_cache = false)
{
    static $cache;
    if ($clear_cache) {
        $cache = null;
        return;
    }

    if (!$cache)
        $cache = array();

    /* etc */

..etc in the following functions:

• set_iri,
• set_authority,
• set_path,

And adding a destructor to SimplePie_IRI calling all the functions using a static cache, with a parameter of true in $clear_cache, will work:

/**
 * Clean up
 */
public function __destruct() {
    $this->set_iri(null, true);
    $this->set_path(null, true);
    $this->set_authority(null, true);
}

Which will now result in no gain in memory consumption over time:

Git Issue