ID: 47712
User updated by: ninzya at inbox dot lv
Reported By: ninzya at inbox dot lv
Status: Open
Bug Type: Scripting Engine problem
Operating System: Windows XP
PHP Version: 5.3.0beta1
New Comment:
I got a little bit closer to the problem. Here's what happens. See this
script:
// load page
$sql ='SELECT id, ' .implode( ', ', $properties) .'
FROM ' .TAB_PREF .'pages
WHERE node_id =' .$Db->escape( $nodeId, 'UINT').'
AND alt_name =' .$Db->escape( $pageAlt, 'STRING') .'
LIMIT 0, 1;';
if(( $row =$Db->queryFirst( $sql)) ===null)
throw new Exception( 'NOT_FOUND');
if( $row['id'] ===null) {// THIS IS WHERE YOU SHOULD LOOK AT
trigger_error( 'Got NULL!', E_USER_WARNING);
trigger_error( 'SQL: ' .$sql, E_USER_WARNING);
ob_start();
var_dump( $row);
trigger_error( ob_get_clean(), E_USER_WARNING);
die();
}
As you can see, i am testing if $row['id'] is null (this is unexpected
situation when this field becomes null, it's an auto column and at this
step i expect successfully fetched row), and if it is NULL, then i wish
to see the debug info for the contents of $row and overall "what's going
on".
Now here is the error log when this unexpected situation is being
RANDOMLY triggered during stress test:
[20-Mar-2009 14:20:37] PHP Warning: Got NULL! in D:\...\pages.php on
line 93
[20-Mar-2009 14:20:37] PHP Warning: SQL: SELECT id, `title`,
`keywords`, `descr`, `template_id`
FROM pages
WHERE node_id =11
AND alt_name ='welcome'
LIMIT 0, 1; in D:\...\pages.php on line 94
[20-Mar-2009 14:20:37] PHP Warning: array(5) {
["id"]=>
string(6) "SHARED"
["title"]=>
string(12) "My test page"
["keywords"]=>
string(6) "asdasd"
["descr"]=>
string(6) "asdasd"
["template_id"]=>
string(4) "8567"
}
in D:\...\pages.php on line 97
I don't know how to explain this. I guess this is mysqlnd failing this
bad.
Previous Comments:
------------------------------------------------------------------------
[2009-03-20 12:12:15] ninzya at inbox dot lv
Every mentioned error/warning occurs randomly. It is not possible to
trigger these warnings (especially first) during each request, something
related to memory fails i think, or stack is being corrupted or
something.
I was investigating this problem for past day and i found this. Take a
look at the following script:
<?php
function throw_exc() {
throw new Exception('TEST_EXCEPTION');
}
class Test {
public function __construct() {
echo 'Constr' ."\n";
}
public function __destruct() {
echo 'Destr' ."\n";
}
}
try {
$T =new Test( throw_exc());
} catch( Exception $e) {
echo 'Exception: ' .$e->getMessage();
}
?>
Execution of this script produces:
Destr
Exception: TEST_EXCEPTION
Where it should produce only this part:
Exception: TEST_EXCEPTION
As you can see, destructor is being called, where it shouldn't be. I
will make a temporary work around for this situation and investigate
further, because i guess this is not the problem that has caused first
warning/error message i mentioned above.
------------------------------------------------------------------------
[2009-03-19 00:30:38] scott...@php.net
Thank you for this bug report. To properly diagnose the problem, we
need a short but complete example script to be able to reproduce
this bug ourselves.
A proper reproducing script starts with <?php and ends with ?>,
is max. 10-20 lines long and does not require any external
resources such as databases, etc. If the script requires a
database to demonstrate the issue, please make sure it creates
all necessary tables, stored procedures etc.
Please avoid embedding huge scripts into the report.
We need an actual reproduce script we can use, I took your small script
and ran it under 5.3.0 without issue.
I'm guessing our errors probably all stem from the same issue, if step
1 or 3 happen then 2 and 4 would be expected due to a lack of database
connection.
------------------------------------------------------------------------
[2009-03-19 00:02:49] ninzya at inbox dot lv
Description:
------------
My configuration is Windows XP, Apache 2.2.11.0, PHP 5.3.0beta1, i'm
coding a framework and periodically i am performing stress tests with
apache's ab.exe. Once my framework has become quite processive (lotsa
operations involved in request processing), there started to appear
unexpected PHP errors/warning in a PHP error log file. For details see
reproduce code.
Reproduce code:
---------------
I was performing periodical stress testing by running "ab.exe -c 30 -n
10000 http://..../myframeworkpage.php";. Sometimes PHP error log had been
empty after 10000 req. stress testing, sometimes there were some
errors/warning (from 1 to 10 usually), and these errors were reporting
absurd things happening around. What i noticed, is that under heavy load
PHP manages to implicitly reset some variables to NULL value, or "lose
value", which results in NULL value. Here are some of those errors and
my assumptions for those errors:
1) "PHP Notice: Use of undefined constant - assumed '' in ... on line
25", where line #25 is "$Db->connect( DB_PERS, DB_HOST, DB_PORT,
DB_USER, DB_PASS);". This is definately failure of PHP.
2) "PHP Fatal error: Call to a member function fetch() on a non-object
in ... on line 611" where line #611 is "while( $this->Db->fetch(
$this->query));". Please note that this cycle is contained within
__destruct() method (probably $Db property is being destroyed too soon
when php execution ends, but i assume it was also implicitly reset to
NULL). Definately failure of PHP.
3) "PHP Warning: mysql_pconnect(): Access denied for user
'root'@'localhost' (using password: NO) in ... on line 163" where line
#163 is "$link =mysql_pconnect( $host .':' .$port, $user, $pass,
$clientFlags);" and $pass was never set to null or whatsoever (it
contains string password, always). I could assume here failure of MySQL
server.
4) "PHP Warning: mysql_real_escape_string() expects parameter 2 to be
resource, null given in ... on line 483" where line #483 is "return '\''
.mysql_real_escape_string( $data, $this->link) .'\'';" and i'm 100% sure
$link property is not null at the step, when call to
mysql_real_escape_string is issued. I could assume here failure of MySQL
server, which resulted in resource to become null (which is also
absurd).
5) "PHP Warning: Invalid argument supplied for foreach() in ... on
line 414" where line #414 is "foreach( $patchset as $blockId =>$fill)",
and $patchset is a reference to an array, always. Definately failure of
PHP.
And much more such examples, which all say the same thing - "i got the
null value, what the hell?".
I tried to make some stress testings for such code as:
class X {
public function __construct() {
}
public function __destruct() {
}
public function test() {
}
public function Y() {
return new Y( $this);
}
}
class Y {
protected $X;
public function __construct( $X) {
$this->X =$X;
}
public function __destruct() {
$this->X->test();
}
}
$X =new X();
$Y =$X->Y();
$C =$X->Y();
$A =$X->Y();
but it executed successfully with no errors. I tried 300000 requests,
everything went fine. But, when i stress-test my framework, PHP
*sometimes* acts weird. So far i failed to find compact reproduction
code for this issue.
Expected result:
----------------
I expect to see no warnings described in "Reproduce code" section.
Actual result:
--------------
PHP under heavy load implicitly resets random variable's value to NULL
or "looses" random variable's value, which results in assignment of NULL
value to that variable.
------------------------------------------------------------------------
--
Edit this bug report at http://bugs.php.net/?id=47712&edit=1
