Memory Management help

Anon

We're hitting an out-of-memory error in our MySQL client in one of our scripts, and I was wondering if someone here could point me to a document that summarizes memory management responsibilities for PHP. What kind of clean-up (if any) needs to be done for class objects, etc? We always call mysql_free_result() after running a MySQL query, so we know that isn't the problem.

Thanks!
Jacob

Anon

PHP 4 has got better memory handling than PHP 3. Are you using PHP 4?

Anon

We're using PHP 3. Is there anything we should be doing besides calling mysql_free_result()?

Thanks!

Anon

In PHP3, that's about what you can do to release memory.

One question, are keeping big arrays in memory while doing multilevel searches? That is one case in which I've seen "out of memory" problems w/ PHP and MySQL.

Also, to make sure that the problem is not happening at the MySQL server end. Try doing the same SQL queries directly to the server, perhaps using the mysql program.

You should consider migrating to PHP4 and take advantage also of the speed up you get from using the Zend Optimizer (free) w/ it.

I recommend reading the articles:

http://www.zend.com/zend/art/ref-count.php

and

http://www.zend.com/zend/art/under-php4-hood.php

which explain the differences a little more.

Of course the source code will tell you exactly how things are done.

Good luck

Anon

The out-of-memory error is actually coming from the mysql call, and--yes--the script is performing a large search. Here is some pseudocode that will give you a feel for what we're doing:

$query = / Get all records from a table /;
$result = mysql_query($query)

for($i=0; $i<msqyl_num_rows($result); $i++)
{
$data1 = mysql_result($result, $i, $column1);
$data2 = mysql_result($result, $i, $column2);
etc...
}

This was working fine until the table grew to a certain size. Any thoughts?

Thanks!

Anon

Within that for loop, we were calling a constructor every time:

for(...)
{
$SomeObject = new SomeClass();

$data = $mysql_result(...);
if(/ $data meets some criteria /)
{/ Do stuff /}
}

Once we moved the constructor into the if statement, the out-of-memory error went away:

for(...)
{
$data = $mysql_result(...);
if(/ $data meets some criteria /)
{
$SomeObject = new SomeClass();
/ Do stuff /
}
}

So, it looks like the multiple constructor calls were the culprits!

Thanks for your help!
Erik