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Bug #42891 mysqli_free_result not freeing memory
Submitted: 2007-10-08 15:10 UTC Modified: 2007-10-08 16:56 UTC
Avg. Score:5.0 ± 0.0
Reproduced:1 of 1 (100.0%)
Same Version:1 (100.0%)
Same OS:1 (100.0%)
From: windeler at mediafinanz dot de Assigned:
Status: Not a bug Package: MySQLi related
PHP Version: 5.2.4 OS: Linux / Windows XP
Private report: No CVE-ID: None
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From: windeler at mediafinanz dot de
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 [2007-10-08 15:10 UTC] windeler at mediafinanz dot de
I am using the latest stable PHP version 5.2.4 on Windows XP (SP2) and Linux (Kernel 2.6.16) and a MySQL Database version 5.0.45.

In both cases mysqli_free_result doesn't seem to free the allocated memory.

Reproduce code:
$db = new mysqli("localhost", "username", "password", "database");

for ($i = 1; $i <= 100; $i++)
    echo 'turn '.$i.'<br />';

    echo "before query: ".memory_get_usage(false).'<br />';

    $dbResult = $db->query("SELECT * FROM example LIMIT $i, $i");

    $row = $dbResult->fetch_assoc();

    echo "before close: ".memory_get_usage(false).'<br />';


    echo "after close: ".memory_get_usage(false).'<br /><br />';

Expected result:
turn 1
before query: 75624
before close: 79736
after close: 75624

turn 2
before query: 75624
before close: 79834
after close: 75624

turn 3
before query: 75624
before close: 79976
after close: 75624


turn 100
before query: 75624
before close: 79858
after close: 75624

Actual result:
turn 1
before query: 75624
before close: 79736
after close: 79872

turn 2
before query: 79872
before close: 84184
after close: 84184

turn 3
before query: 84184
before close: 84200
after close: 84240


turn 100
before query: 85360
before close: 85360
after close: 85360


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 [2007-10-08 16:56 UTC]
Thank you for taking the time to write to us, but this is not
a bug. Please double-check the documentation available at and the instructions on how to report
a bug at

memory_get_usage() only counts memory allocated by PHP and modules which use PHP\'s memory mangment routines. The libmysql allocates it\'s memory itself therefore PHP doesn\'t know about it.
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