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-   -   PHP Code Optimization: Do's and Don'ts (http://www.go4expert.com/articles/php-code-optimization-dos-donts-t13769/)

hurricanesoftwares 12Sep2008 16:48

PHP Code Optimization: Do's and Don'ts
 
I am listing tips to improve your PHP code performance. There are few whom you can call as debatable but overall the code performance will surely increase.

Following tips are written to save time and development cost (includes memory too)
  • If a method can be static, declare it static. Speed improvement is by a factor of 4.
  • echo is faster than print.
  • Use echo's multiple parameters instead of string concatenation.
  • Set the maxvalue for your for-loops before and not in the loop.
  • Unset your variables to free memory, especially large arrays.
  • Avoid magic like __get, __set, __autoload
  • require_once() is expensive
  • Use full paths in includes and requires, less time spent on resolving the OS paths.
  • If you need to find out the time when the script started executing, $_SERVER[’REQUEST_TIME’] is preferred to time()
  • See if you can use strncasecmp, strpbrk and stripos instead of regex
  • str_replace is faster than preg_replace, but strtr is faster than str_replace by a factor of 4
  • If the function, such as string replacement function, accepts both arrays and single characters as arguments, and if your argument list is not too long, consider writing a few redundant replacement statements, passing one character at a time, instead of one line of code that accepts arrays as search and replace arguments.
  • It's better to use switch statements than multi if, else if, statements.
  • Error suppression with @ is very slow.
  • Turn on apache's mod_deflate
  • Close your database connections when you're done with them
  • $row[’id’] is 7 times faster than $row[id]
  • Error messages are expensive
  • Do not use functions inside of for loop, such as for ($x=0; $x < count($array); $x) The count() function gets called each time.
  • Incrementing a local variable in a method is the fastest. Nearly the same as calling a local variable in a function.
  • Incrementing a global variable is 2 times slow than a local var.
  • Incrementing an object property (eg. $this->prop++) is 3 times slower than a local variable.
  • Incrementing an undefined local variable is 9-10 times slower than a pre-initialized one.
  • Just declaring a global variable without using it in a function also slows things down (by about the same amount as incrementing a local var). PHP probably does a check to see if the global exists.
  • Method invocation appears to be independent of the number of methods defined in the class because I added 10 more methods to the test class (before and after the test method) with no change in performance.
  • Methods in derived classes run faster than ones defined in the base class.
  • A function call with one parameter and an empty function body takes about the same time as doing 7-8 $localvar++ operations. A similar method call is of course about 15 $localvar++ operations.
  • Surrounding your string by ' instead of " will make things interpret a little faster since php looks for variables inside "..." but not inside '...'. Of course you can only do this when you don't need to have variables in the string.
  • When echoing strings it's faster to separate them by comma instead of dot. Note: This only works with echo, which is a function that can take several strings as arguments.
  • A PHP script will be served at least 2-10 times slower than a static HTML page by Apache. Try to use more static HTML pages and fewer scripts.
  • Your PHP scripts are recompiled every time unless the scripts are cached. Install a PHP caching product to typically increase performance by 25-100% by removing compile times.
  • Cache as much as possible. Use memcached - memcached is a high-performance memory object caching system intended to speed up dynamic web applications by alleviating database load. OP code caches are useful so that your script does not have to be compiled on every request
  • When working with strings and you need to check that the string is either of a certain length you'd understandably would want to use the strlen() function. This function is pretty quick since it's operation does not perform any calculation but merely return the already known length of a string available in the zval structure (internal C struct used to store variables in PHP). However because strlen() is a function it is still somewhat slow because the function call requires several operations such as lowercase & hashtable lookup followed by the execution of said function. In some instance you can improve the speed of your code by using an isset() trick.

    Ex.

    PHP Code:

    if (strlen($foo) < 5) { echo "Foo is too short"; } 

    vs.

    PHP Code:

    if (!isset($foo{5})) { echo "Foo is too short"; } 

    Calling isset() happens to be faster then strlen() because unlike strlen(), isset() is a language construct and not a function meaning that it's execution does not require function lookups and lowercase. This means you have virtually no overhead on top of the actual code that determines the string's length.

  • When incrementing or decrementing the value of the variable $i++ happens to be a tad slower then ++$i. This is something PHP specific and does not apply to other languages, so don't go modifying your C or Java code thinking it'll suddenly become faster, it won't. ++$i happens to be faster in PHP because instead of 4 opcodes used for $i++ you only need 3. Post incrementation actually causes in the creation of a temporary var that is then incremented. While pre-incrementation increases the original value directly. This is one of the optimization that opcode optimized like Zend's PHP optimizer. It is a still a good idea to keep in mind since not all opcode optimizers perform this optimization and there are plenty of ISPs and servers running without an opcode optimizer.
  • Not everything has to be OOP, often it is too much overhead, each method and object call consumes a lot of memory.
  • Do not implement every data structure as a class, arrays are useful, too
  • Don't split methods too much, think, which code you will really re-use
  • You can always split the code of a method later, when needed
  • Make use of the countless predefined functions
  • If you have very time consuming functions in your code, consider writing them as C extensions
  • Profile your code. A profiler shows you, which parts of your code consumes how many time. The Xdebug debugger already contains a profiler. Profiling shows you the bottlenecks in overview
  • mod_gzip which is available as an Apache module compresses your data on the fly and can reduce the data to transfer up to 80%

All the above can be used to reduce the processing time and you can make your client happy.

I hope everyone will be following the tips.

mihirkothari 18Sep2008 12:44

Re: PHP Code Optimization: Do's and Don'ts
 
humm i didn't knew most of these. Do they really matter? I am going to try them out now..

codestorm 18Sep2008 17:14

Re: PHP Code Optimization: Do's and Don'ts
 
Yeah me too, thanks for sharing.

seangtz 27Sep2008 14:00

Re: PHP Code Optimization: Do's and Don'ts
 
I didn't tried, after reading your post I'm planning to try them out now..

shabbir 2Oct2008 21:41

Re: PHP Code Optimization: Do's and Don'ts
 
Nominated for article of the month for September 2008

gandu 3Oct2008 18:27

Re: PHP Code Optimization: Do's and Don'ts
 
Hi,

This is really an excellent article. Thank you very much for sharing this with us. Being a beginner in PHP, this is some resource for me. Can you tell me where to ask basic questions in PHP in this forum?

shabbir 17Oct2008 09:15

Re: PHP Code Optimization: Do's and Don'ts
 
Start Voting for article of the month for September 2008

gandu 19Oct2008 19:00

Re: PHP Code Optimization: Do's and Don'ts
 
Quote:

Originally Posted by shabbir

how to vote for the article? can you give me a clue?

shabbir 19Oct2008 20:33

Re: PHP Code Optimization: Do's and Don'ts
 
Quote:

Originally Posted by gandu
how to vote for the article? can you give me a clue?

As of now you would not be able to as you do not have necessary post count.

sarah_9 24Jan2009 16:01

Re: PHP Code Optimization: Do's and Don'ts
 
Hello,

Good post buddy, and thanks for sharing such useful and informative post, it is not on;y useful for novice, but also for professionals of the field.



Regards,
sarah_9

chaosprime 26Jan2009 20:38

Re: PHP Code Optimization: Do's and Don'ts
 
A lot of those are corollaries of "Error messages are expensive". (That doesn't mean that you shouldn't put error messages in your code; it means that you should avoid triggering PHP's automatic errors and warnings.)

You can address that in a very general way by, in development and staging, using error_reporting(E_ALL) and reworking your code to avoid whatever messages are generated. Too often, people use error_reporting(0) or @func() calls to just suppress messages, which is a bad idea for performance and a bad idea for debugging.

Lizapotter 25Feb2009 11:16

Re: PHP Code Optimization: Do's and Don'ts
 
Excellent article, Here are come more points :

1. Not everything has to be OOP, often it is too much overhead, each method and object call consumes a lot of memory.
2. Do not implement every data structure as a class, arrays are useful, too
3. Don't split methods too much, think, which code you will really re-use
4. You can always split the code of a method later, when needed
5. Make use of the countless predefined functions
6. If you have very time consuming functions in your code, consider writing them as C extensions

gkumar 17Jun2009 15:54

Re: PHP Code Optimization: Do's and Don'ts
 
great job, Thanks for sharing this.

WoRLDLiFE 11Dec2009 19:29

Re: PHP Code Optimization: Do's and Don'ts
 
Thank you man ! very good article many points I was not knowing. From next time when creating a script I'll try to keep all this in mind.

jaikanth123 13Jan2010 15:24

Re: PHP Code Optimization: Do's and Don'ts
 
php means hyper text preprocessor or personal home page...PHP is a widely-used general-purpose scripting language that is especially suited for Web development and can be embedded into HTML.and to produce dynamic web pages. For this purpose PHP code is embedded into the HTML source document and interpreted by a web server with a PHP processor module, which generates the web page document. As a general-purpose programming language, PHP code is processed by an interpreter application in command line mode performing desired operating system operations and producing program output on its standard output channel. It may also function as a graphical application. PHP is available as a processor for most modern web servers and as standalone interpreter on almost every operating system and computing platform.

step1: mod_deflate for Apache 2.0

If your host runs Apache 2 you can use mod_deflate. Despite its name, mod_deflate also uses gzip compression. To configure mod_deflate, add the following directives to your .htaccess file.

step2:Option 2: mod_deflate for Apache 2.0

If your host runs Apache 2 you can use mod_deflate. Despite its name, mod_deflate also uses gzip compression. To configure mod_deflate, add the following directives to your .htaccess file.

step3(Variant 2): PHP Settings in .htaccess

If your host allows you to set PHP settings in your .htaccess file, then you no longer need to use php.ini file to configure your compression settings. Instead, set the PHP setting in .htaccess using php_value (and php_flag).

step 4: In-script Compression.

If your hosting provider doesn't allow you to use php_value in your .htaccess file, nor do they allow you to use a custom php.ini file, your last resort is to modify the scripts to manually include the common pre.php file that will take care of the compression. This is the least-preferred option, but sometimes you may have no other alternative.

step 5: do not enable tags
File ETags none

Note that this rule applies to sites that are in a server farm. If you're using a shared host, you could skip this step, but I recommend that you do it regardless because:

* Hosts change their machines for internal purposes.
* You may change hosts.
* It's so simple.

qforever 22Jan2010 18:00

Re: PHP Code Optimization: Do's and Don'ts
 
In addition:
If you need to use a big volume of data SQL usage preferrable. "SELECT" usually much faster than "for()". BUT is you has a finite list of items that will never be changed(such as list of states) it's faster to store it in PHP array than make separated SQL table and add it to all queries.

loyo 25Feb2010 08:45

Re: PHP Code Optimization: Do's and Don'ts
 
So good article it is . thank you for sharing.

Prateek.sem 26Apr2010 13:58

Re: PHP Code Optimization: Do's and Don'ts
 
nice post.. useful too

johnny.dacu 14Jul2010 00:58

Re: PHP Code Optimization: Do's and Don'ts
 
Nice article, even if is not original. I think i might have read it somewhere.


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