- Foreach is 4-5 times faster than For
- Nested Foreach is 2-3 times faster than nested For
- Foreach with key lookup is 2-3 times slower than Foreach without
- C++ is 5-300 times faster than PHP running For/Foreach on Arrays
- HHVM is 2-3 times faster than PHP
- PHP 7 is 2-4 times faster than PHP 5.5
- HHVM is currently no alternative to C++
- Javascript is 2-20 times slower than C++/Java running For on nested Arrays
- Go is 4-20 times faster than HHVM
Here is a sample script:
<?php
function test(){
// init arrays
$array = array();
for ($i=0; $i<50000; $i++) $array[] = $i*2;
$array2 = array();
for ($i=20000; $i<21000; $i++) $array2[] = $i*2;
// test1: foreach big-array (foreach small-array)
$start = microtime(true);
foreach ($array as $val) {
foreach ($array2 as $val2) if ($val == $val2) {}
}
echo number_format(microtime(true)-$start, 2)."s\n";
// test1b: foreach big-array (foreach small-array)
$start = microtime(true);
foreach ($array as $val) {
foreach ($array2 as $val2) if ($val === $val2) {}
}
echo number_format(microtime(true)-$start, 2)."s\n";
// test2: foreach small-array (foreach big-array)
$start = microtime(true);
foreach ($array2 as $val2) {
foreach ($array as $val) if ($val == $val2) {}
}
echo number_format(microtime(true)-$start, 2)."s\n";
// test3: foreach big-array (foreach small-array) with key lookup
$start = microtime(true);
foreach ($array as $key=>$val) {
foreach ($array2 as $key2=>$val2) if ($array[$key] == $array2[$key2]) {}
}
echo number_format(microtime(true)-$start, 2)."s\n";
// test4: foreach small-array (foreach big-array) with key lookup
$start = microtime(true);
foreach ($array2 as $key=>$val2) {
foreach ($array as $val) if ($array[$key] == $array2[$key2]) {}
}
echo number_format(microtime(true)-$start, 2)."s\n";
// test5: for big-array (for small-array)
$start = microtime(true);
$count = count($array);
$count2 = count($array2);
for ($key=0; $key<$count; $key++) {
for ($key2=0; $key2<$count2; $key2++) if ($array[$key] == $array2[$key2]) {}
}
echo number_format(microtime(true)-$start, 2)."s\n";
// test6: for small-array (for big-array)
$start = microtime(true);
$count = count($array);
$count2 = count($array2);
for ($key2=0; $key2<$count2; $key2++) {
for ($key=0; $key<$count; $key++) if ($array[$key] == $array2[$key2]) {}
}
echo number_format(microtime(true)-$start, 2)."s\n";
$array = array();
for ($i=0; $i<1000000; $i++) $array[] = $i*2;
// test7: foreach big-array
$start = microtime(true);
foreach ($array as &$val) $val++;
echo number_format(microtime(true)-$start, 2)."s\n";
// test8: for big-array
$start = microtime(true);
for ($key=0; $key<count($array); $key++) $array[$key]++;
echo number_format(microtime(true)-$start, 2)."s\n";
// test8b: for big-array, doing count() outside the loop!
$start = microtime(true);
$count = count($array);
for ($key=0; $key<$count; $key++) $array[$key]++;
echo number_format(microtime(true)-$start, 2)."s\n";
}
test();
Here are some results from PHP 5.4.4 and HHVM (2014-05-04, QEMU 2.3 GHz, 64bit): Using HHVM instead of PHP gives big improvements.
With Javascript (node.js) you'll get similar values:
example.js (run: node example.js)
tested with QEMU 2.3 GHz, node.js v0.10
var array = [];
for (i=0; i<50000; i++) array.push(i*2);
var array2 = [];
for (i=20000; i<21000; i++) array2.push(i*2);
// js-test1: for big-array (for small array)
var start = new Date().getTime();
var length = array.length;
var length2 = array2.length;
for (key=0; key<length; key++) {
for (key2=0; key2<length2; key2++) if (array[key] == array2[key2]) {}
}
console.log((new Date().getTime() - start) / 1000); // 1.53s
// js-test2: foreach big-array (foreach small array)
start = new Date().getTime();
for (key in array) {
for (key2 in array2) if (array[key] == array2[key2]) {}
}
console.log((new Date().getTime() - start) / 1000); // 6.32s
var array3 = [];
for (i=0; i<1000000; i++) array3.push(i*2);
// js-test3: for big-array
start = new Date().getTime();
length3 = array3.length;
for (key=0; key<length3; key++) array3[key]++;
console.log((new Date().getTime() - start) / 1000); // 0.03s
With C++ (gcc 4.6 win32) you'll also get similar values:
example.cpp (run: g++ -o example example.cpp && ./example)
tested with QEMU 2.3 GHz, gcc 4.7
#include <sys/time.h>
#include <stdio.h>
#include <vector>
using namespace std;
main() {
struct timeval start, end;
vector<int> array;
for(int i=0; i < 50000; i++) array.push_back(i*2);
vector<int> array2;
for(int i=20000; i < 21000; i++) array2.push_back(i*2);
gettimeofday(&start, NULL);
int array_size = array.size();
int array2_size = array2.size();
for (int key=0; key<array_size; key++)
for (int key2=0; key2<array2_size; key2++)
if (array[key] == array2[key2]) {}
gettimeofday(&end, NULL);
printf("%lf\n", (float)(end.tv_sec - start.tv_sec +
(end.tv_usec - start.tv_usec)/1000000.0)); // 0.61s, 0.00s (-O3)
vector<int> array3;
for(int i=0; i < 1000000; i++) array3.push_back(i*2);
gettimeofday(&start, NULL);
int array3_size = array3.size();
for(int i=0; i < array3_size; i++) array3[i]++;
gettimeofday(&end, NULL);
printf("%lf\n", (float)(end.tv_sec - start.tv_sec +
(end.tv_usec - start.tv_usec)/1000000.0)); // 0.009s, 0.001s (-O3)
}
And Java (Java 1.7 win64):
example.java (run: javac -g:none example.java && java example)
tested with QEMU 2.3 GHz, OpenJDK 1.6, 64bit
import java.util.ArrayList;
import java.util.Vector;
public class example {
public static void main(String[] args) throws Exception {
ArrayList<Integer> array = new ArrayList<Integer>();
for (int i = 0; i < 50000; i++) array.add(i*2);
ArrayList<Integer> array2 = new ArrayList<Integer>();
for (int i = 20000; i < 21000; i++) array2.add(i*2);
long start = System.currentTimeMillis();
int array_size = array.size();
int array2_size = array2.size();
for (int key = 0; key < array_size; key++)
for (int key2 = 0; key2 < array2_size; key2++)
if (array.get(key).equals(array2.get(key2))) {}
System.out.println((float) (System.currentTimeMillis() - start) / 1000);
// 0.066s
Vector<Integer> varray = new Vector<Integer>();
for (int i = 0; i < 50000; i++) varray.add(i*2);
Vector<Integer> varray2 = new Vector<Integer>();
for (int i = 20000; i < 21000; i++) varray2.add(i*2);
start = System.currentTimeMillis();
int varray_size = varray.size();
int varray2_size = varray2.size();
for (int key = 0; key < varray_size; key++)
for (int key2 = 0; key2 < varray2_size; key2++)
if (varray.get(key).equals(varray2.get(key2))) {}
System.out.println((float) (System.currentTimeMillis() - start) / 1000);
// 1.652s
ArrayList<Integer> array3 = new ArrayList<Integer>();
for (int i = 0; i < 1000000; i++) array3.add(i*2);
start = System.currentTimeMillis();
int array3_size = array3.size();
for (int i = 0; i < array3_size; i++) array3.set(i, array3.get(i)+1);
System.out.println((float)(System.currentTimeMillis() - start) / 1000);
// 0.164s
Vector<Integer> varray3 = new Vector<Integer>();
for (int i = 0; i < 1000000; i++) varray3.add(i*2);
start = System.currentTimeMillis();
int varray3_size = varray3.size();
for (int i = 0; i < varray3_size; i++) varray3.set(i, varray3.get(i)+1);
System.out.println((float)(System.currentTimeMillis() - start) / 1000);
// 0.074s
}
}
Go (1.4.2):
example.go (run: go build example.go && ./example)
package main
import "fmt"
import "time"
func main() {
var array [50000]int
for i := 0; i < 50000; i++ { array[i] = i*2 }
var array2 [1000]int
for i := 20000; i < 21000; i++ { array2[i-20000] = i*2 }
t := time.Now()
length := len(array)
length2 := len(array2)
for key := 0; key < length; key++ {
for key2 := 0; key2 < length2; key2++ {
if (array[key] == array2[key2]) {}
}
}
fmt.Println(time.Now().Sub(t)) // 157.855682ms
var array3 [1000000]int
for i := 0; i < 1000000; i++ { array3[i] = i*2 }
t2 := time.Now()
length3 := len(array3)
for key := 0; key < length3; key++ { array3[key]++ }
fmt.Println(time.Now().Sub(t2)) // 4.363528ms
}
Zephir (0.7.1b):
example.zep (run: zephir init utils && vi utils/example.zep && zephir build && php -d extension=utils.so -r 'echo Utils\Example::run();')
namespace Utils;
class Example {
public static function run() {
int i, i2;
array array1 = [];
let i = 0;
while (i < 50000) {
let array1[] = i*2;
let i++;
}
array array2 = [];
let i = 20000;
while (i < 21000) {
let array2[] = i*2;
let i++;
}
var start;
let start = microtime(true);
int length, length2;
let length = count(array1);
let length2 = count(array2);
let i = 0, i2 = 0;
while (i < length) {
while (i2 < length2) {
if (array1[i] == array2[i2]) {}
let i2++;
}
let i++;
}
echo (microtime(true) - start) . PHP_EOL;
array array3 = [];
let i = 0;
while (i < 1000000) {
let array3[] = i*2;
let i++;
}
let start = microtime(true);
int length3;
let length3 = count(array3);
let i = 0;
while (i < length3) {
let array3[i] += 1;
let i++;
}
echo (microtime(true) - start) . PHP_EOL;
}
}
New results (AMD Opteron 6128 2GHz virtualized):
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Note:
instead of
int len = array.size(); for (int key=0; key < len; key++)
makes the code 30 percent faster!
for (int key=0; key < array.size(); key++)
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