test.php

<?php

// Get 10mb of data from /dev/zero
$infp = fopen('/dev/zero', 'r');
$data = fread($infp, 1024 * 1024 * 10);
fclose($infp);

write_data($data);

echo "Peak memory usage: ", number_format(memory_get_peak_usage()), " bytes\n";

/**
 * Bad example of how to write some data to /dev/null
 */
function write_data($data)
{
  $outfp = fopen('/dev/null', 'w');
  fwrite($outfp, $data . "\n");
  fclose($outfp);
}