Edit report at https://bugs.php.net/bug.php?id=77879&edit=1
ID: 77879
Updated by: requi...@php.net
Reported by: xxalfa at gmail dot com
Summary: Usable memory
Status: Open
Type: Bug
Package: Testing related
Operating System: Windows
PHP Version: 7.3.4
Block user comment: N
Private report: N
New Comment:
Your script is quitting because PHP didn't need to allocate more memory to
handle another 1k characters. Why is that a bug?
Previous Comments:
------------------------------------------------------------------------
[2019-04-12 01:48:30] xxalfa at gmail dot com
Description:
------------
The following script fills the memory with pointless data. Now the problem:
From one point, the function "memory_get_usage" returns the same value,
although the level has changed. This is important if you want to process data
and save it only when a certain number of results have been generated. The
second problem: Why are only 40% usable?
Test script:
---------------
<?php
// C:\Users\User\Desktop\php-on-limit.cmd
// @echo off
// title PHP Development Server
// cd "%cd%"
// rem "C:\php\php.exe" "php-on-limit.php"
// "C:\php\php.exe" "-d memory_limit=16M" "php-on-limit.php"
// pause
// C:\Users\User\Desktop\php-on-limit.php [PHP:7.3.3][PID:6336]
//-------------------------------------------------
// HEAD
//-------------------------------------------------
declare( strict_types = 1 );
header( 'Content-Type:text/plain' );
error_reporting( E_ALL );
ini_set( 'display_errors', '1' );
ini_set( 'html_errors', '0' );
define( 'CORE_DIR', dirname( __FILE__ ) . DIRECTORY_SEPARATOR );
isset( $argv ) or trigger_error( 'This is a command terminal application.',
E_USER_ERROR );
echo __FILE__ . ' [PHP:' . phpversion() . '][PID:' . getmypid() . ']' .
PHP_EOL . PHP_EOL;
//-------------------------------------------------
// CODE
//-------------------------------------------------
$measuring_point_of_time = microtime( true );
$memory_limit = conversion_back_to_bytes( ini_get( 'memory_limit' ) );
echo 'memory_limit -- ' . human_readable_file_size( $memory_limit ) . ' --
defined limit' . PHP_EOL;
// $memory_limit *= 0.48; // 48% of 128M can only be used
// $memory_limit *= 0.47; // 47% of 64M can only be used
$memory_limit *= 0.40; // 40% of 16M can only be used
// If the 40% is exceeded, it comes to a fatal error, which is not
desirable.
// Fatal error: Allowed memory size of 16 MByte exhausted (tried to
allocate 6 MByte).
echo 'memory_limit -- ' . human_readable_file_size( $memory_limit ) . ' --
usable limit' . PHP_EOL;
echo 'memory_allocated -- ' . human_readable_file_size( memory_get_usage(
true ) ) . ' -- memory_used -- ' . memory_get_usage() . PHP_EOL;
$something_has_to_be_calculated = true;
$results_of_the_calculations = null;
$last_memory_usage = memory_get_usage();
while ( $something_has_to_be_calculated )
{
$results_of_the_calculations .= str_repeat( '1', 1024 );
$currently_memory_usage = memory_get_usage();
if ( $currently_memory_usage === $last_memory_usage )
{
echo PHP_EOL . 'Process recording: Memory function has not changed.
currently_memory_usage and last_memory_usage are ' . $currently_memory_usage .
PHP_EOL;
break;
}
// echo chr( 0xD );
echo 'memory_allocated -- ' . human_readable_file_size(
memory_get_usage( true ) ) . ' -- memory_used -- ' . memory_get_usage() . ' --
data_length -- ' . strlen( $results_of_the_calculations );
echo PHP_EOL;
if ( memory_get_usage() >= 20 * 1024 * 1024 )
{
echo PHP_EOL . 'Process recording: Normal break.' . PHP_EOL;
break;
}
if ( memory_get_usage() >= $memory_limit )
{
echo PHP_EOL . 'Process recording: Memory limit reached. Save
calculated results so far.' . PHP_EOL;
$results_of_the_calculations = null;
}
$last_memory_usage = memory_get_usage();
}
echo PHP_EOL;
$results_of_the_calculations = null;
echo 'Process recording: Calculations completed. Results are saved.' .
PHP_EOL . PHP_EOL;
echo 'Processing time: ' . elapsed_time( $measuring_point_of_time ) . '
seconds.' . PHP_EOL . PHP_EOL;
//-------------------------------------------------
// FUNCTIONS
//-------------------------------------------------
function elapsed_time( $measuring_point_of_time )
{
return number_format( microtime( true ) - $measuring_point_of_time, 3 );
}
function human_readable_file_size( $file_size, $precision = 2 )
{
$label = array( 'Bytes', 'kByte', 'MByte', 'GByte', 'TByte', 'PByte',
'EByte', 'ZByte', 'YByte' );
return $file_size ? round( $file_size / pow( 1024, ( $index = floor(
log( $file_size, 1024 ) ) ) ), $precision ) . ' ' . $label[ $index ] : '0
Bytes';
}
function conversion_back_to_bytes( $value )
{
$unit = strtolower( substr( $value, -1 ) );
if ( $unit == 'k' ): return (integer) $value * 1024; endif;
if ( $unit == 'm' ): return (integer) $value * 1048576; endif;
if ( $unit == 'g' ): return (integer) $value * 1073741824; endif;
return $value;
}
?>
Expected result:
----------------
The "memory_get_usage" function must continually display the current memory
usage to effectively operate at the memory limit.
Actual result:
--------------
C:\Users\User\Desktop\php-on-limit.php [PHP:7.3.4][PID:1224]
memory_limit -- 16 MByte -- defined limit
memory_limit -- 6.4 MByte -- usable limit
memory_allocated -- 2 MByte -- memory_used -- 410408
memory_allocated -- 2 MByte -- memory_used -- 411688 -- data_length -- 1024
memory_allocated -- 2 MByte -- memory_used -- 412968 -- data_length -- 2048
memory_allocated -- 2 MByte -- memory_used -- 414504 -- data_length -- 3072
memory_allocated -- 2 MByte -- memory_used -- 418600 -- data_length -- 4096
Process recording: Memory function has not changed. currently_memory_usage and
last_memory_usage are 418520
Process recording: Calculations completed. Results are saved.
Processing time: 0.001 seconds.
------------------------------------------------------------------------
--
Edit this bug report at https://bugs.php.net/bug.php?id=77879&edit=1
