How do I know how much memory my application uses in PHP?

Question

I wonder if there is any way to know how much my PHP application is consuming memory.

For example: I want to know, at the end of the script execution, how much PHP spent on the execution process of a given script.

Is there any PHP function I can do this check for?

Answer 1

As has already been quoted, memory_get_usage captures current memory expenditure. However, there is another function, the memory_get_peak_usage, that picks up the maximum recorded memory peak.

Note: so much memory_get_usage how much memory_get_peak_usage only achieves the result defined by emalloc() is returned.

So the differences are:

• memory_get_usage returns the approximate current memory expense, for example:

  <?php
  
  echo round(memory_get_usage() / 1024, 4), 'Kb', PHP_EOL; // 219.2656Kb
  
  $a = str_repeat("Hello", 4242);
  
  echo round(memory_get_usage() / 1024, 4), 'Kb', PHP_EOL; // 240.1797Kb
  
  unset($a);
  
  echo round(memory_get_usage() / 1024, 4), 'Kb', PHP_EOL; // 219.3125Kb
  

  The values vary depending on the system and version used of PHP, also varies if using extensions such as Opcache or XCache

• memory_get_peak_usage returns the memory peak spent so far, then

  <?php
  
  echo round(memory_get_peak_usage() / 1024, 4), 'Kb', PHP_EOL; // 222.8906Kb
  
  $a = str_repeat("Hello", 4242);
  
  echo round(memory_get_peak_usage() / 1024, 4), 'Kb', PHP_EOL; // 241.7422Kb
  
  unset($a);
  
  echo round(memory_get_peak_usage() / 1024, 4), 'Kb', PHP_EOL; // 241.8047Kb
  

  See that the numbers remain and always increase.

Testing at the end of the script

There is a function called register_shutdown_function which runs at the end of the script, would be like a "__destruct ", at this point it is interesting to check the memory peak, thus:

<?php

register_shutdown_function(function() {
    echo PHP_EOL, round(memory_get_peak_usage() / 1024, 4), 'Kb';
});

$a = str_repeat("Hello", 4242);

unset($a);

So whenever the larger script is terminated (those that are included do not trigger this function unless there is a exit; or die('foo');) and will add to the end of the output/output/body of the document the result of how much was spent.

Note: register_shutdown_function may be added at any time before the shutdown

Here about extensions

• /a/152472/3635
• /a/166747/3635

Answer 2

The function memory_get_usage returns the number of bytes allocated to the script.

An example taken from the PHP documentation:

// É apenas um exemplo os números serão diferentes dependendo do sistema
echo memory_get_usage() . "\n"; // 36640

$a = str_repeat("Hello", 4242);

echo memory_get_usage() . "\n"; // 57960

unset($a);

echo memory_get_usage() . "\n"; // 36744

Answer 3

memory_get_usage:

memory_get_usage() returns the amount of byte memory that is being used by your php script.

DEMONSTRATION:

echo memory_get_usage(); // 112388 (bytes)

If you put the argument as true (memory_get_usage(true)), is returned the total memory reserved on the system for your php script:

DEMONSTRATION, with argument input as true:

echo memory_get_usage(true); // 262144 (bytes)

So if you want the real memory that the system is using you should do as the last demo above, memory_get_usage(true)

And if you want to know the real memory that your script consumed (within the reserved memory, obviously) use the first example.