How to know the amount of memory used by my PHP application?

As already mentioned, memory_get_usage captures memory expenditure at the moment . However, there is another function, memory_get_peak_usage , which takes the peak of maximum registered memory.

  

Note: both memory_get_usage and < a href="http://php.net/manual/en/function.memory-get-peak-usage.php"> memory_get_peak_usage "only gets the result defined by emalloc() is returned.

So the differences are:

• memory_get_usage returns the approximate current memory spend , 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 by PHP, it also varies if you are using extensions like Opcache or XCache

• memory_get_peak_usage returns peak memory 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 stay and always increase.

Testing at the end of the script

There is a function called register_shutdown_function that runs at the end of the script, it would be like a "% global_content", at this point it is interesting to do the peak memory check, like this:

<?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 finished (those that are included do not fire this function unless there is a __destruct or exit; ) and will add the result of the output / output / body of the document to the end of the output / how much was spent.

  

Note: die('foo'); can be added at any time before shutdown

Here about extensions

• link
• link

The memory_get_usage function 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

memory_get_usage :

memory_get_usage() returns the amount of memory in bytes 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) ), the total reserved memory in the system for your php script is returned:

DEMONSTRATION , with argument input as true :

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

In other words, if you want the actual memory that the system is using you should do as in the last demo above, memory_get_usage(true)

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