Why did this php page consume almost 100% of a huge server's CPU time?

[kisazeky]

I had an account suspended on a paid, shared web host recently.  They said it was because one of my php pages was taking up more than 10% CPU time.  What's shocking is that looking at the reports, it was nearly 10 times that!

 

Top Process %CPU 97.0 /usr/bin/php /home/digiado1/public_html/buy.php

Top Process %CPU 76.3 /usr/bin/php /home/digiado1/public_html/buy.php

Top Process %CPU 71.4 /usr/bin/php /home/digiado1/public_html/buy.php

 

Now I have a hunch as to why this happened.  Here's a bit of code from buy.php:

 

$query = "SELECT * FROM `users` WHERE `username` = '".$luser."'";
$result = mysql_query($query);
$num = mysql_numrows($result);
$i=0;
while ($i < 1) {

$money =@mysql_result($result,$i,"money");

$query = "SELECT * FROM adoptables WHERE uid = '$aID'";
$result = @mysql_query($query);
$num = @mysql_numrows($result);

//Loop out code
$i=0;
while ($i < 1) {

$aID=@mysql_result($result,$i,"uid");
$name=@mysql_result($result,$i,"name");
$imageurl=@mysql_result($result,$i,"imageurl");
$cost=@mysql_result($result,$i,"description");

if($money < $cost){
$article_title = "Oops";
$article_content = "You don't have enough bits to afford $name. <a href='shop.php'>Go back</a>.";
}

else {

 

I noticed that when the conditions met that If statement, the page would time out.

 

So I added

 

$i++;
}

 

to close the output of both those queries, and now it loads fine.

 

So my question to you php freaks is:

 

Is it likely that not closing the output properly caused this much load on the CPU?

 

I don't get much traffic to my site.

 

 

[Mchl]

Your script got into an infinite loop, and these tend to hog resources.

[jackpf]

Error supression with @ is supposed to be costly when executing php. Only by milliseconds, but still. There's not really much point in doing it.

[Maq]

Which loop did you add the $i++ into?  There are 2 while loops..

[jackpf]

Yeah, and think about it - if $i = 0, and you're not incrementing it, it's always going to be 0. So the statement "while($i < 1)" will always return true.

[taquitosensei]

plus you've got two $i loops so every loop you're overwriting what $i was with the 2nd loop.

[gffg4574fghsDSGDGKJYM]

$result and $i are used in 2 differents while loop one inside the other. It just can't work. Rename them in one the 2 loop, and post the full file for more help.

[kisazeky]

I did this:

 

$query = "SELECT * FROM `users` WHERE `username` = '".$luser."'";
$result = mysql_query($query);
$num = mysql_numrows($result);
$i=0;
while ($i < 1) {

$money =@mysql_result($result,$i,"money");

$i++;
}

$query = "SELECT * FROM adoptables WHERE uid = '$aID'";
$result = @mysql_query($query);
$num = @mysql_numrows($result);

//Loop out code
$i=0;
while ($i < 1) {

$aID=@mysql_result($result,$i,"uid");
$name=@mysql_result($result,$i,"name");
$imageurl=@mysql_result($result,$i,"imageurl");
$cost=@mysql_result($result,$i,"description");

$i++;
}

 

Does this stop the infinite loop? 

[Mchl]

It does... You could however just as well remove both loops, as both of them run once only.

 

Edit:

 

It seems to me like you should replace

while ($i < 1) {

 

with

 

while ($i < $num) {

 

in both cases for this code to make (some) sense

[Maq]

That shouldn't cause an infinite loop.

 

Although, I don't get the point of a while loop when it's only going to loop once...

[Mchl]

See my edited post above

[wildteen88]

Looking at your code you do not need to use any form of loop. As you're only returning one result. You could of done it this way:

 

$query = "SELECT money FROM `users` WHERE `username` = '".$luser."'";
$result= mysql_query($query);
if(mysql_num_rows($result) != 0)
{
    list($money) = mysql_fetch_row($result);

    $query = "SELECT name, imageurl, description FROM adoptables WHERE uid = '$aID'";
    $result = mysql_query($query);

    list($name, $imageurl, $cost) = mysql_num_rows($result);
}

 

 

 

[kisazeky]

Thanks, teen.  I was modeling this off of someone else's code, so I believed you had to loop queries all the time.

 

From now on I'll use what you showed me unless I really do need to loop data.

 

 

[wildteen88]

Oops Just to let you know I had a typo in the code.

 

This line

list($name, $imageurl, $cost) = mysql_num_rows($result);

should of been

list($name, $imageurl, $cost) = mysql_fetch_row($result);

 

To clarify you only need to use a loop if you are planning on retrieving more than one result from the query.