ID: 45178
User updated by: thomas dot jarosch at intra2net dot com
Reported By: thomas dot jarosch at intra2net dot com
Status: Assigned
Bug Type: Reproducible crash
Operating System: Linux
PHP Version: 5.3CVS-2008-06-04 (snap)
Assigned To: dmitry
New Comment:
Thanks for looking into this, Dmitry!
So there are actually two problems, one memory corruption reported
here and one memory leak report in #33595 or are they both memory
corruptions?
Previous Comments:
------------------------------------------------------------------------
[2008-07-15 11:42:00] [EMAIL PROTECTED]
The simplest case for this memory corruption.
<?php
class Foo {
function Foo() {
$this->error = array($this,$this);
}
}
$a =& new Foo();
------------------------------------------------------------------------
[2008-07-15 07:37:50] [EMAIL PROTECTED]
At first, you have a serious issue in your code. "static" variables
MUST NOT be asigned by reference, because they are already references.
As result the singleton pattern just doesn't work. BTW the bug is really
exists. The simplified test case follows(changing "=& new" into "= new"
fixes memory corruption).
<?php
class Horde_History {
function raiseError() {
return debug_backtrace();
}
function Horde_History() {
$this->error = $this->raiseError();
echo "Memory usage: " . memory_get_usage() . "\n";
}
}
for ($i=0;$i<100000;$i++) {
$a =& new Horde_History();
}
?>
------------------------------------------------------------------------
[2008-06-05 09:13:20] thomas dot jarosch at intra2net dot com
Actually, the reproduce code from #33595 also leaks memory.
The statement about Horde is not 100% correct as only some singleton
functions are affected. I mixed it up with another reference problem
I fixed a while ago. Nontheless memory is leaked :-)
------------------------------------------------------------------------
[2008-06-04 16:57:45] thomas dot jarosch at intra2net dot com
Description:
------------
Hello together,
I'm currently trying to find a heap corruption while using Horde and
noticed a rather odd behavior. The supplied code is the standard way
Horde does it singletons. We always used the syntax of "$object =
&new class" to make it work with PHP4 and PHP5.
If I change that to "$object = new class", everything works as
expected. I've found bug #32845 and noticed what we are doing seems
wrong, so Horde needs fixing.
The problem gets worse if the class object contains a variable of the
type "PEAR_Error", which contains cyclic references. Not only does
the constructor get called every time, the object leaks memory like
hell, even with PHP 5.3. I've searched through the bugtracker and
thought the garbage collector now handles cyclic references,
but maybe this is a side-effect of something else going wrong.
Is the memory consumption by design?
Thanks in advance for any comment,
Thomas
Reproduce code:
---------------
<?php
require_once "PEAR.php";
class Horde_History
{
var $error;
function &singleton()
{
static $history;
if (!isset($history)) {
$history = &new Horde_History();
}
return $history;
}
function Horde_History()
{
$this->error = PEAR::raiseError("error");
echo "Memory usage: " . memory_get_usage() . "\n";
}
}
for (;;) {
$a = Horde_History::singleton();
}
Expected result:
----------------
Constant memory usage.
Actual result:
--------------
Increasing memory usage.
------------------------------------------------------------------------
--
Edit this bug report at http://bugs.php.net/?id=45178&edit=1
