Description:
------------
I did some memory tests to compare PHP 7.0.0RC2 (TS, 64bit) with 5.x versions and realized a strange behavior when using memory_get_usage() with $real_usage set to TRUE.

I did a first call of memory_get_usage(true), produced some data and did a second call of memory_get_usage(true), before using the data. Then I compared the logged memory consumption.

In the example below I got a memory difference of about 78 MB when calling the script the first time, the next time I called the script I got about the half of this value, and further calls reduced it more and more until I got to 0 bytes between the first and second call of memory_get_usage(true).

After a restart of the web server (Apache 2.4) I get the same behavior again.

NOTE: $real_usage set to FALSE works as expected.

Test script:
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<?php
$oldMem = memory_get_usage(true);

$array = array();
for ($i=1; $i <= 10000; $i++) {
    $array[$i] = range(1, 96);
}

$newMem = memory_get_usage(true);

echo "Array size: " . count($array) . "<br>";
echo "Memory consumption BEFORE: " . $oldMem . "<br>";
echo "Memory consumption AFTER: " . $newMem . "<br>";

Expected result:
----------------
Result of the first 10 calls after the restart of the web server:

Array size: 10000
Memory consumption BEFORE: 2097152
Memory consumption AFTER: 83886080

Array size: 10000
Memory consumption BEFORE: 2097152
Memory consumption AFTER: 83886080

Array size: 10000
Memory consumption BEFORE: 2097152
Memory consumption AFTER: 83886080

Array size: 10000
Memory consumption BEFORE: 2097152
Memory consumption AFTER: 83886080

Array size: 10000
Memory consumption BEFORE: 2097152
Memory consumption AFTER: 83886080

Array size: 10000
Memory consumption BEFORE: 2097152
Memory consumption AFTER: 83886080

Array size: 10000
Memory consumption BEFORE: 2097152
Memory consumption AFTER: 83886080

Array size: 10000
Memory consumption BEFORE: 2097152
Memory consumption AFTER: 83886080

Array size: 10000
Memory consumption BEFORE: 2097152
Memory consumption AFTER: 83886080

Array size: 10000
Memory consumption BEFORE: 2097152
Memory consumption AFTER: 83886080

Actual result:
--------------
Result of the first 10 calls after the restart of the web server:

Array size: 10000
Memory consumption BEFORE: 2097152
Memory consumption AFTER: 83886080

Array size: 10000
Memory consumption BEFORE: 2097152
Memory consumption AFTER: 44040192

Array size: 10000
Memory consumption BEFORE: 2097152
Memory consumption AFTER: 23068672

Array size: 10000
Memory consumption BEFORE: 2097152
Memory consumption AFTER: 12582912

Array size: 10000
Memory consumption BEFORE: 2097152
Memory consumption AFTER: 8388608

Array size: 10000
Memory consumption BEFORE: 2097152
Memory consumption AFTER: 6291456

Array size: 10000
Memory consumption BEFORE: 2097152
Memory consumption AFTER: 4194304

Array size: 10000
Memory consumption BEFORE: 2097152
Memory consumption AFTER: 4194304

Array size: 10000
Memory consumption BEFORE: 2097152
Memory consumption AFTER: 4194304

Array size: 10000
Memory consumption BEFORE: 2097152
Memory consumption AFTER: 2097152