在PHP中，如何检查某个循环使用的内存量

I'm currently making a PHP timer that checks how much time a certain way of doing something takes compared to another thing that accomplishes the same, basically benchmarking.

Now, I would also like to make this tool be able to tell how much memory that specific way of doing it is taking up.

So, for more info, I'm using microtime to check the start time, do 2000 thousand loops on that code and then do another microtime with some math to check how much time it took, so what I would like to do is, outside the microtime scope, also check for memory usage.

This is my current code:

// Set the amount of loops to do, default is 2000
$loops = 2000;
$start_time = microtime(true); // Start the timer

for($i = 0; $i < $loops; $i++) {
    // Code to test
}

$total_time = microtime(true) - $start_time; // Stop the timer, and figure out the total

ob_end_flush();   // Enable output again
echo $total_time; // Echo the timer's result
?>

You could use memory_get_usage (http://php.net/manual/en/function.memory-get-usage.php) when you think the process is at its peak.

Or you could also just call it occasionally and record whatever was the highest value... or as you please.

But this is within a process. Are you talking about a PHP process "A" checking another PHP process' memory usage?

If so:

$myPID = getmypid();
$stats = explode("
", shell_exec('pmap $(pgrep php) | grep \'total\\|\\:\''));
for ($i = 0; $i < count($stats); $i += 2) {
    if (strpos($stats[$i], "$myPID") === false) {
        preg_match('/\d+/', $stats[$i+1], $preRes);
        $res = $preRes[0];
    }
}
//if $res has a value, that value is the kilobytes of memory being used by the other PHP process

This solution has a problem: if you have more than 2 php processes running total, you can't guarantee that you will be getting the right process.

To solve this, run first the other process, obtain its PID and then pass it as argument to this process. If you have the process' PID you want to check, you could just do this:

$stats = explode("
", shell_exec('pmap $(pgrep php) | grep \'total\\|\\:\''));
for ($i = 0; $i < count($stats); $i += 2) {
    if (strpos($stats[$i], "$otherPID") === 0) {
        preg_match('/\d+/', $stats[$i+1], $preRes);
        $res = $preRes[0];
    }
}
//$res contains the result you want in kilobytes

You could check the memory for all processes that are not you, too:

$myPID = getmypid();
$stats = explode("
", shell_exec('pmap $(pgrep php) | grep \'total\\|\\:\''));
for ($i = 0; $i < count($stats) - 1; $i += 2) {
    if (strpos($stats[$i], "$myPID") === false) {
        preg_match('/\d+/', $stats[$i+1], $preRes);
        $res[] = $preRes[0];
    }
}

So to get the maximum memory usage, just keep a $max variable and keep checking against it.

If you're on at least 5.2, memory_get_peak_usage() should work just fine.

http://php.net/manual/en/function.memory-get-peak-usage.php

You can call it once prior to the loop to get an idea of your baseline up to that point, then again afterward to see what peak was during loop execution.

Modifying your code...

// Set the amount of loops to do, default is 2000
$loops = 2000;
$base_mem = memory_get_peak_usage();
$start_time = microtime(true); // Start the timer

for($i = 0; $i < $loops; $i++) {
    // Code to test
}
$end_time = microtime(true);  // Stop the timer
$extra_mem = memory_get_peak_usage();

// figure out the totals
$total_time = $end_time - $start_time;
$total_mem = $extra_mem - $base_mem;

ob_end_flush();   // Enable output again
echo "Total Time: $total_time
";
echo "Total Mem Above Basline: $total_mem bytes
";