40 Tips for optimizing your php Code (opens in new tab)

(reinholdweber.com)

13 pointsraindoll18y ago11 comments

11 comments

6 comments · 3 top-level

some18y ago· 3 in thread

> Set the maxvalue for your for-loops before and not in the loop.

What does this mean?

raindollOP18y ago

it means that this:

$maxvalue = 100/10; for($i=0; $i<$maxvalue; $i++){ // Some code }

is much faster than this:

for($i=0; $i<100/10; $i++){ // Some code }

because the value is calculated once instead of ten times.

ratsbane18y ago

That's not necessarily true. If the compiler is smart enough it won't recalculate the value of a numeric expression which doesn't contain any variables. On the other hand, dereferencing a variable isn't without cost. Of course, in most cases you'd be dereferencing variables anyway in the test clause, so the original idea, compute loop limits before entering the loop, is correct.:

mbp:~/test doug$ time php -r 'for ($i=1; $i<100000000/10; $i++) {$x++;};'

  real    0m5.930s
  user    0m5.867s
  sys     0m0.026s

  mbp:~/test doug$ time php -r '$maxval=100000000/10; for ($i=1; $i<$maxval; $i++) {$x++;};'

  real    0m6.999s
  user    0m6.907s
  sys     0m0.029s



  mbp:~/test doug$ time perl -e 'for ($i=1; $i<100000000/10; $i++) {$x++;}'

  real    0m2.520s
  user    0m2.496s
  sys     0m0.010s

  mbp:~/test doug$ time perl -e '$maxval=100000000/10; for ($i=1; $i<$maxval; $i++) {$x++;}'

  real    0m2.537s
  user    0m2.499s
  sys     0m0.014s

The results are a little different with Python (maxval1.py computes inline; maxval2 divides in advance and uses variable inline)

  mbp:~/test doug$ time python maxval1.py

  real    0m2.134s
  user    0m1.761s
  sys     0m0.276s

  mbp:~/test doug$ time python maxval2.py

  real    0m1.890s
  user    0m1.588s
  sys     0m0.278s

Java shows even more of a difference (again, maxval2 sets variable in advance):

  mbp:~/test doug$ time java maxval1

  real    0m0.174s
  user    0m0.116s
  sys     0m0.040s

  mbp:~/test doug$ time java maxval2

  real    0m0.531s
  user    0m0.125s
  sys     0m0.041s

2 more replies

some18y ago

Ok. The same comes again at point 15:

> Do not use functions inside of for loop, such as for ($x=0; $x < count($array); $x) The count() function gets called each time.

some18y ago

> 1. If a method can be static, declare it static. Speed improvement is by a factor of 4.

Wow!

 function Prime1() { ...calc one million prime numbers...}

 static function Prime2() { ...calc one million prime numbers...}

Prime2() will calculate the prime numbers 4 times faster then Prime1()? Cool.

jbyers18y ago

These range from sensible to utterly useless [1,2,3].

I'd say forget all of this and focus on being a productive developer, building something people want, and ruthlessly avoiding premature optimization. When your application is slow, measure it to find out why, then fix it, and repeat.

1. Let's take #2, "echo is faster than print" - Seriously, is this what we should be worrying about? I can't detect a difference in PHP 5.2.4 across 100,000 echos/prints, so it must not be very big.

2. ++i vs i++ to squeeze out 1 fewer opcode?

3. Using isset($foo{5}) vs a strlen check? I pity the next programmer who has to read and understand the purpose of this code.

j / k navigate · click thread line to collapse

11 comments

6 comments · 3 top-level

some18y ago· 3 in thread

> Set the maxvalue for your for-loops before and not in the loop.

What does this mean?

raindollOP18y ago

it means that this:

$maxvalue = 100/10; for($i=0; $i<$maxvalue; $i++){ // Some code }

is much faster than this:

for($i=0; $i<100/10; $i++){ // Some code }

because the value is calculated once instead of ten times.

ratsbane18y ago

mbp:~/test doug$ time php -r 'for ($i=1; $i<100000000/10; $i++) {$x++;};'

  real    0m5.930s
  user    0m5.867s
  sys     0m0.026s

  mbp:~/test doug$ time php -r '$maxval=100000000/10; for ($i=1; $i<$maxval; $i++) {$x++;};'

  real    0m6.999s
  user    0m6.907s
  sys     0m0.029s



  mbp:~/test doug$ time perl -e 'for ($i=1; $i<100000000/10; $i++) {$x++;}'

  real    0m2.520s
  user    0m2.496s
  sys     0m0.010s

  mbp:~/test doug$ time perl -e '$maxval=100000000/10; for ($i=1; $i<$maxval; $i++) {$x++;}'

  real    0m2.537s
  user    0m2.499s
  sys     0m0.014s

The results are a little different with Python (maxval1.py computes inline; maxval2 divides in advance and uses variable inline)

  mbp:~/test doug$ time python maxval1.py

  real    0m2.134s
  user    0m1.761s
  sys     0m0.276s

  mbp:~/test doug$ time python maxval2.py

  real    0m1.890s
  user    0m1.588s
  sys     0m0.278s

Java shows even more of a difference (again, maxval2 sets variable in advance):

  mbp:~/test doug$ time java maxval1

  real    0m0.174s
  user    0m0.116s
  sys     0m0.040s

  mbp:~/test doug$ time java maxval2

  real    0m0.531s
  user    0m0.125s
  sys     0m0.041s

2 more replies

some18y ago

Ok. The same comes again at point 15:

> Do not use functions inside of for loop, such as for ($x=0; $x < count($array); $x) The count() function gets called each time.

some18y ago

> 1. If a method can be static, declare it static. Speed improvement is by a factor of 4.

Wow!

 function Prime1() { ...calc one million prime numbers...}

 static function Prime2() { ...calc one million prime numbers...}

Prime2() will calculate the prime numbers 4 times faster then Prime1()? Cool.

jbyers18y ago

These range from sensible to utterly useless [1,2,3].

1. Let's take #2, "echo is faster than print" - Seriously, is this what we should be worrying about? I can't detect a difference in PHP 5.2.4 across 100,000 echos/prints, so it must not be very big.

2. ++i vs i++ to squeeze out 1 fewer opcode?

3. Using isset($foo{5}) vs a strlen check? I pity the next programmer who has to read and understand the purpose of this code.

j / k navigate · click thread line to collapse