Home » Database » DB » Bug #1112

[2004-04-01 16:10 UTC] bemis at docutronsystems dot com

Description:
------------
The row->free() function doesn't work when the Results are empty.
I wanted a basic daemon that selected every two seconds, and did an action based upon the select results.
most of the time the select will return nothing.
I am finding that after two days of running this piece of my daemon my computer is hanging.
I can rewrite this in c, but my whole project is in PHP so I wanted to use PHP in case the project ever needs to be passed on.

Reproduce code:
---------------
#!/usr/bin/php -q
<?php
include 'DB.php';
$db_object = DB::connect('mysql://root:root@localhost/client_files', TRUE);
$db_object->setFetchMode(DB_FETCHMODE_ASSOC);
while(true)
{
usleep(500000);//dont go crazy
$res=$db_object->query( "select doc_id from this_should_work where doc_id=2" );
$row=$res->fetchRow();
//this is a dumbed down version, but does the memleak
$res->free();
unset($row);
unset($res);
echo memory_get_usage()."\n";
}
?>

Expected result:
----------------
I expect that the memory doesn't increase:
so I'd like to see the script output
502608
502608
502608
502608
502608
502608
502608
502608
502608
502608
502608
502608
502608

Actual result:
--------------
what I actually see is our script increasing at a rate of about 120 bytes per loop:
502608
502784
502904
503024
503144
503264
503384
503504
503656
503776
503896
504016
504136
504256
504376
504496
504680
504800

[2004-04-01 20:36 UTC] bemis at docutronsystems dot com

new script as you requested
#!/usr/bin/php -q
<?php
include 'DB.php';
$db_object = DB::connect('mysql://root:root@localhost/client_files',
TRUE);
$db_object->setFetchMode(DB_FETCHMODE_ASSOC);
for( $i=0;$i<1000;$i++)
{
$res=$db_object->query( "select doc_id from this_should_work where doc_id=2" );
$row=$res->fetchRow();
//this is a dumbed down version, but does the memleak
$res->free();
unset($row);
unset($res);
if( $i%50==1 )
echo memory_get_usage()."\n";
}
?>

new results of that script
[root@death poll]# ./try.php
503456
509680
515936
522448
528448
534448
538464
541264
544064
546864
549664
554512
557312
560112
562912
565712
568512
571312
574112
576912
-matt

[2004-04-01 20:44 UTC] bemis at docutronsystems dot com

I upgraded with pear upgrade db, and got the following output
[root@death poll]# pear upgrade DB
downloading DB-1.6.1.tgz ...
Starting to download DB-1.6.1.tgz (89,932 bytes)
.....................done: 89,932 bytes
upgrade ok: DB 1.6.1

then I ran it again
[root@death poll]# ./try.php
521288
524488
527688
530888
534088
537288
537480
537480
537480
537480
537480
537480
537480
537480
537480
537480
537480
537480
537480
537480
I use yum upgrade as often as I see available upgrades. I dont think it upgraded pear though.
I am sorry for any problems
-matt

[2004-04-01 20:56 UTC] bemis at docutronsystems dot com

after upgrading it does not seem to be a problem any more.
I cranked the for loop up to 100000 and the memory size stayed the same after the 5th iteration.