anonymous function performance in PHP [closed]

Question

I'm starting to use functional programming paradigms in php and was wondering what the performance impacts are. Some googling just seems to say that there are some. To be specific, I would like to know:

• Is there actually a performance impact or is it an urban legend?
• What is the performance impact (hopefully someone out that has done benchmarks)?
• What causes this impact (if one exists)?
• Is it fixed cost, or per execution?

Any resources you guys have would be greatly appreciated :)

Thanks in advance

Answer 1

I did some testing with array_map(), calling it with:

1. The name of a function (array_map('test', $myArray);)
2. A variable that contains a closure (array_map($test, $myArray);)
3. A closure (array_map(function{}(), $myArray);)

In all three cases, the function was empty (function test(){})

The results for an array with 1.000.000 items ($myArray = range(1,1000000);)

Function: 0.693s
Variable:0.703s
Closure: 0.694s

For an array of 10.000.000 items, the results are this:

Function: 8.913s
Variable: 8.169s
Closure: 8.117s

So in neither case do we have much overhead, if any.

Also see the 4th comment on http://fabien.potencier.org/article/17/on-php-5-3-lambda-functions-and-closures It comes to the same conclusions. In that comment, you also see that create_function() is significantly slower.