Code looping & Crashing server. No idea what's happening - php

Question

I've got a serious issue here. I'm developing a forum, and trying to get an "unread posts" feature ready. However, for some reason my code decides to loop & get ridiculous CPU usage over my dedi. All i see from my MySQL process list is that the same sql is constantly looping.
This is my code:
public function __construct()
{
$this->getUnread();
}
private function getUnread()
{
global $cms;
// check unread threads
$forumSQL = $cms->db->query('SELECT * FROM forum_for');
while($forums = $forumSQL->fetch_assoc())
{
$forumId = $forums['id'];
$forumArray[$forumId] = $forums;
}
if($unreadThreadsSql = $cms->db->query('SELECT * FROM forum_threads WHERE posted > "' . $_SESSION['lastVisit'] . '"'))
{
while(!$unreadThreads = $unreadThreadsSql->fetch_assoc())
{
$forumId = $unreadThreads['forId'];
if($this->checkUnread($unreadThreads['id']))
{
$cms->db->query('
INSERT INTO
forum_unread(
threadID,
catID,
forumID,
userID,
datetime,
threadtime)
VALUES(
'.$unreadThreads['id'].',
'.$forumArray[$forumId]['cat_id'].',
'.$forumId.',
'.$_SESSION['userId'].',
NOW(),
"'.$unreadThreads['posted'].'" )');
}
}
}
// check unread posts
if($unreadPostsSql = $cms->db->query('SELECT * FROM forum_posts WHERE datetime > "' . $_SESSION['lastVisit'] . '"'))
{
while($unreadPosts = $unreadPostsSql->fetch_assoc())
{
$threadSql = $cms->db->query('SELECT * FROM forum_threads WHERE id = ' . $unreadPosts['threadId']);
$thread = $threadSql->fetch_assoc();
$forumId = $thread['forId'];
if(!$this->checkUnread($thread['id']))
{
$cms->db->query('
INSERT INTO
forum_unread(
threadID,
catID,
forumID,
userID,
datetime,
threadtime)
VALUES(
'.$thread['id'].',
'.$forumArray[$forumId]['cat_id'].',
'.$forumId.',
'.$_SESSION['userId'].',
NOW(),
"'.$thread['posted'].'" )');
}
}
}
}
private function checkUnread($id)
{
global $cms;
if($unreadSql = $cms->db->query('SELECT * FROM forum_unread WHERE threadID = ' .$id . ' AND userID = ' . $_SESSION['userId']))
{
if($unreadSql->num_rows == 1)
{
return true;
}
else
{
return false;
}
}
else
{
return false;
}
}
Could really use some help here. I really can't find why it's looping, does anyone have an idea...
For whose wondering, it seems the code is looping in the function checkUnread().
As an extra note, when commenting the $this->getUnread(); in the constructor the entire thing stops overloading. So i'm certain it's in this bit of code.

Answer 1

Did you mean while($unreadThreads = $unreadThreadsSql->fetch_assoc())?
BTW it would be highly more efficient if you composed one big INSERT query then executed it once, rather than all of these little bitty queries.
Example:
$inserts = Array();
$unreadThreadsSql = $cms->db->query('SELECT * FROM forum_threads WHERE posted > "' . $_SESSION['lastVisit'] . '"') or die($cms->db->error);
while ($unreadThreads = $unreadThreadsSql->fetch_assoc()) {
$forumId = $unreadThreads['forId'];
if (!$this->checkUnread($unreadThreads['id']))
continue;
$inserts[] = '(' .
$unreadThreads['id'] . ',' .
$forumArray[$forumId]['cat_id'] . ',' .
$forumId . ',' .
$_SESSION['userId'] . ',' .
'NOW(),' .
'"' . $unreadThreads['posted'] . '")'
);
}
if (count($inserts)) {
$cms->db->query('INSERT INTO forum_unread(
threadID,
catID,
forumID,
userID,
datetime,
threadtime) VALUES' .
implode(',', $inserts)) or die($cms->db->error);
}