php - Performance of foreach, array_map with lambda and array_map with static function

Question

What's the performance difference (if there is any) between these three approaches, both used to transform an array to another array?

1. Using foreach
2. Using array_map with lambda/closure function
3. Using array_map with 'static' function/method
4. Is there any other approach?

To make myself clear, let's have look at the examples, all doing the same - multiplying the array of numbers by 10:

$numbers = range(0, 1000);

---

Foreach

$result = array();
foreach ($numbers as $number) {
    $result[] = $number * 10;
}
return $result;

---

Map with lambda

return array_map(function($number) {
    return $number * 10;
}, $numbers);

---

Map with 'static' function, passed as string reference

function tenTimes($number) {
    return $number * 10;
}
return array_map('tenTimes', $numbers);

---

Is there any other approach? I will be happy to hear actually all differences between the cases from above, and any inputs why one should be used instead of others.

Answer 1

Its interesting to run this benchmark with xdebug disabled, as xdebug adds quite a lot of overhead, esp to function calls.

This is FGM's script run using 5.6 With xdebug

ForEach   : 0.79232501983643
MapClosure: 4.1082420349121
MapNamed  : 1.7884571552277

Without xdebug

ForEach   : 0.69830799102783
MapClosure: 0.78584599494934
MapNamed  : 0.85125398635864

Here there is only a very small difference between the foreach and closure version.

Its also interesting to add a version with a closure with a use

function useMapClosureI($numbers) {
  $i = 10;
  return array_map(function($number) use ($i) {
      return $number * $i++;
  }, $numbers);
}

For comparison I add:

function useForEachI($numbers)  {
  $result = array();
  $i = 10;
  foreach ($numbers as $number) {
    $result[] = $number * $i++;
  }
  return $result;
}

Here we can see it makes an impact on the closure version, whereas the array hasn't noticeably changed.

19/11/2015 I have also now added results using PHP 7 and HHVM for comparison. The conclusions are similar, though everything is much faster.

PHP 5.6

ForEach    : 0.57499806880951
MapClosure : 0.59327731132507
MapNamed   : 0.69694859981537
MapClosureI: 0.73265469074249
ForEachI   : 0.60068697929382

PHP 7

ForEach    : 0.11297199726105
MapClosure : 0.16404168605804
MapNamed   : 0.11067249774933
MapClosureI: 0.19481580257416
ForEachI   : 0.10989861488342

HHVM

ForEach    : 0.090071058273315
MapClosure : 0.10432276725769
MapNamed   : 0.1091267824173
MapClosureI: 0.11197068691254
ForEachI   : 0.092114186286926