What is better practice for script performance tuning?
This one?
require_once("db.php");
if (!is_cached()) {
require_once("somefile.php");
require_once("somefile2.php");
//do something
} else {
//display something
}
Or this one?
require_once("db.php");
require_once("somefile.php");
require_once("somefile2.php");
if (!is_cached()) {
//do something
} else {
//display something
}
Is it worth placing includes/requires into flow control structures or no?
Thank you
Yes, it will increase performance and contrary to what others said, the impact may not be negligible.
When you include/require files, PHP will check all the defined include_paths until it finds the file or there is nothing more to check. Depending on the amount of include pathes and the amount of files to include, this will have a serious impact on your application, especially when including each and every file up front. Lazy including (like in your first example) or - even better - using the Autoloader is advisable.
Related reading that addresses this in more details:
Zend Framework Performance Guide*
*The advice given there is applicable to any application or framework
Includes and requires are designed in part to allow you to organize your code and make maintaining your software easier to do. While there technically is a performance hit for using includes it is negligible and more then offset by increasing the maintainability of your software. Especially if you use an opcode cache. I wouldn't worry about this and chalk it up to premature optimization.
It can sometimes be worth it if the required files are huge, and no byte code cache is available.
The issue then, however, is not really the number of include() statements, but the amount of data that gets included. The less unused code you include in a request, the better.
A good remedy to monolithic includes is splitting the code base into smaller ones, or, if your application is largely object oriented, using PHP's autoloading feature.
I've seen shared hosting packages where un-tangling monolithic includes could save up to half a second - which is a lot.
Also, included PHP code gets parsed and takes up memory, whether it's executed or not. A clean structure with lean objects is usually the optimal way.
Yes, it will increase performance, but it is very very little so it isn't worth it.
Using absolute paths for include files will increase performance significantly. Test using Apache Benchmark to see if it doesn't.
Related
I have a website which uses a lot of constants, that are defined like this, for example:
define('CONSTANT', 1)
I currently have a list of about 200 defines like this. This list is run every time a page loads. Is this going to affect my performance or memory use badly?
There are reasons to avoid a list of 200 constants on every page load, but performance and memory usage would not be among them. In general, the best way to answer these kinds of questions is to run benchmarks. Measure page load time and memory usage both with and without loading your 200 constants. Measure a few thousand times and look at the numbers. I suspect you'll find a negligible difference. Micro-optimization is usually a waste of time.
I would imagine not. Are you having performance issues with your script? If not, then don't worry about it. If so, then what have you done to determine where the bottleneck lies?
If you need to know how long it's taking to include and parse the file with your defines in, then I'd suggest you time it.
$start = microtime (true);
include ('file_to_include.php');
echo (microtime (true) - $start);
Why all of the defines? it will likely only slow you down if you have a lot of traffic. if you are putting them all to use i could see that slowing it down pretty good. what's the reason maybe there is a better way (i've never needed more than 5 constants)
I don't think it will have more impact than reading the file that contains 200 constants, then again it will be optimized by your disk cache. At least it is better than reading 200 constants from database. If you do care about performance, install an op cache, therefore, it will not require any additional parsing every time. For memory it depends on the type of your constants but it wont be much.
I have about a 2000 line functions file, and I have realized I can split it up into a bout 4 files, and only include the one's required. At the moment it is very neat, and ideally I would like to leave it that way, however if speed increases can be gained I would like to only include the different sections on particular conditions.
My question is basically, would it be quicker to have an if statement and only load the php functions needed. Speed is a factor, as this library is called in an ajax polling situation.
best approach would be to divide all your code into meaningful folders/files/classes/functions. This serves the purpose of maintainable and readable code.
And then use some kind of cache like APC whih removes the problem of many includes/IOs almost completely.
So I'm working on a project written in old-style (no OOP) PHP with no full rewrite in the near future. One of the problems with it currently is that its slow—much of the time is spent requireing over 100 files based on where it is in the boot process.
I was wondering if we could condense this (on deployment, not development of course) into a single file or two with all the require'd text just built in. However, since there are so many lines of code that aren't used for each page, I'm wondering if doing this would backfire.
At its core, I think, it's a question of whether:
<?php
echo 'hello world!';
?>
is any faster than
<?php
if(FALSE) {
// thousands of lines of code here
}
echo 'hello world!';
?>
And if so, how much slower?
(Also, if what I've outlined above is a bad idea for some other reasons, please let me know.)
The difference between the two will be negligible. If most of the execution time is currently spent requiring files you're likely to see a significant boost by using an optcode cache like APC, if you are not already.
Other than that - benchmark, find out exactly where the bottlenecks are. In my experience requires are often the slowest part of an old-style procedural PHP app, but even with many included files I'd be surprised if these all added up to a 'slow' app.
Edit: ok, a quick 'n dirty benchmark. I created three 'hello world' PHP scripts like the example. The first (basic.php) was just echoing the string. The second (complex.php) included an if false statement that contained ~5000 lines of PHP code pasted in from another app. The third (require.php) included the same if statement but required in the ~5000 lines of code from another file.
Page generation time (as measured by microtime()) between basic.php and complex.php was around ~0.000004 seconds, so really not significant. Some more comprehensive results from apache bench:
without APC with APC
req/sec avg (ms) req/sec avg (ms)
basic.php: 7819.87 1.277 6960.49 1.437
complex.php: 346.82 2.883 352.12 2.840
require.php: 6819.24 1.446 5995.49 1.668
APC's not doing a lot here but using up memory, but it's likely to be a different picture in a real world app.
require does have some overhead. 100 requires is probably a lot. Parsing an entire file that has the 100 includes is probably slow too. The overhead from require might cost you more, but it is hard to say. It might not cost you enough.
All benchmarks are evil, but here is what I did:
ran a single include of a file that was about 8000 lines (didn't do anything useful each line, just declares a variable). Compared to the time it takes to run an include of an 80 line file (same declarations) 100 times. Results were inconclusive.
Is the including of the files really causing the problem? Is there not something in the script execution that can be optimized? Caching may be an option..
Keep in mind that PHP will parse all the code it sees, even if it's not run.
It will still take relatively long to process the a file too, and from experience, lots of code will eat up considerable amounts of memory even though they're not executed.
Opcode caching as suggested by #Tim should be your first port of call.
If that is out of the question (e.g. due to server limitations): If the functions are somehow separable into categories, one possibility to make things a bit faster and lighter could be (ab)using PHP's Autoloading by putting the functions into separate files as methods of static classes.
function xyz() { ... }
would become
class generic_tools
{
public static function xyz() { ... }
}
and any call to xyz() is replaced by generic_tools::xyz();
The call would then trigger the inclusion of (e.g.) generic_tools.class.php on demand, instead of including everything at once.
This would require rewriting the function calls to static method calls, which may be dead easy or a bit more difficult (if function calls are cooked up dynamically or something). But beyond that, no refactoring would be needed, because you're not really using any OOP mechanisms.
How much this will actually help strongly depends on the app's architecture and how intertwined the functions are with each other.
What kind of ideas or tips and tricks do you have in order to boost PHP performance.
Something like,
I use:
$str = 'my string';
if(isset($str[3])
Instead of:
if(strlen($str) > 3)
Which is a bit faster.
Or storing values as keys instead of vars in array, makes searching if key exists much faster. Hence using isset($arr[$key]) instead of array_exists($arr, $key)
Shoot your ideas, i would love to hear them.
Use a profiler and measure your performance.
Optimise the areas that need it.
Typical areas that will give you the most bang for effort in a typical php website.
think about database queries carefully. They often take up most of the execution time.
Don't include code you don't need
Don't write you own versions of the built in functions - the built in ones are compiled C and will be faster that you L33T php version.
Use an OpCode cache.
Most PHP accelerators work by caching the compiled bytecode of PHP scripts to avoid the overhead of parsing and compiling source code on each request (some or all of which may never even be executed). To further improve performance, the cached code is stored in shared memory and directly executed from there, minimizing the amount of slow disk reads and memory copying at runtime.
Dont do as list of this things, you'll make your code unreadable... or harder to read, even by yourself.
Leave this things to the Zend Engine, or to the accelerator of your choice( actually a opcode cache).
Optimizations like these may be faster now, but they may actually get slower if the guys from the zend engine starts to auto-optimize things like these.
Ex: one may speed up the strlen() function a lot by giving up on z-strings and using l-strings(the length being in the first char, or word). This in turn will end up making your (pre-optimized) script slower if you optimize like this.
Use parameterized SQL instead of mysql_query(). And reduce the overall number of database queries. Everything else are shallow optimizations.
I generally include 1 functions file into the hader of my site, now this site is pretty high traffic and I just like to make every little thing the best that I can, so my question here is,
Is it better to include multiple smaller function type files with just the code that's needed for that page or does it really make no difference to just load it all as 1 big file, my current functions file has all the functions for my whole site, it's about 4,000 lines long and is loaded on every single page load sitewide, is that bad?
It's difficult to say. 4,000 lines isn't that large in the realms of file parsing. In terms of code management, that's starting to get on the unwieldy side, but you're not likely to see much of a measurable performance difference by breaking it up into 2, 5 or 10 files, and having pages include only the few they need (it's better coding practice, but that's a separate issue). Your differential in number-of-lines read vs. number-of-files that the parser needs to open doesn't seem large enough to warrant anything significant. My initial reaction is that this is probably not an issue you need to worry about.
On the opposite side of the coin, I worked on an enterprise-level project where some operations had an include() tree that often extended into the hundreds of files. Profiling these operations indicated that the time taken by the include() calls alone made up 2-3 seconds of a 10 second load operation (this was PHP4).
If you can install extensions on your server, you should take a look at APC (see also).
It is free, by the way ;-) ; but you must be admin of your server to install it ; so it's generally not provided on shared hosting...
It is what is called an "opcode cache".
Basically, when a PHP script is called, two things happen :
the script is "compiled" into opcodes
the opcodes are executed
APC keeps the opcodes in RAM ; so the file doesn't have to be re-compiled each time it is called -- and that's a great thing for both CPU-load and performances.
To answer the question a bit more :
4,000 lines is not that much, speaking of performances ; Open a couple of files of any big application / Framework, and you'll rapidly get to a couple thousand of lines
a really important thing to take into account is maintenability : what will be easier to work with for you and your team ?
loading many small files might imply many system calls, which are slow ; but those would probably be cached by the OS... So probably not that relevant
If you are doing even 1 database query, this one (including network round-trip between PHP server and DB server) will probably take more time than the parsing of a couple thousand lines ;-)
I think it would be better if you could split the functions file up into components that is appropriate for each page; and call for those components in the appropriate pages. Just my 2 cents!
p/s: I'm a PHP amateur and I'm trying my hands on making a PHP site; I'm not using any functions. So can you enlighten me on what functions would you need for a site?
In my experience having a large include file which gets included everywhere can actually kill performance. I worked on a browser game where we had all game rules as dynamically generated PHP (among others) and the file weighed in at around 500 KiB. It definitely affected performance and we considered generating a PHP extension instead.
However, as usual, I'd say you should do what you're doing now until it is a performance problem and then optimize as needed.
If you load a 4000 line file and use maybe 1 function that is 10 lines, then yes I would say it is inefficient. Even if you used lots of functions of a combined 1000 lines, it is still inefficient.
My suggestion would be to group related functions together and store them in separate files. That way if a page only deals with, for example, database functions you can load just your database functions file/library.
Anothe reason for splitting the functions up is maintainability. If you need to change a function you need to find it in your monalithic include file. You may also have functions that are very, very similar but don't even realise it. Sorting functions by what they do allows you to compare them and get rid of things you don't need or merge two functions into one more general purpose function.
Most of the time Disc IO is what will kill your server so I think the lesser files you fetch from disc the better. Furthermore if it is possible to install APC then the file will be stored compiled into memory which is a big win.
Generally it is better, file management wise, to break stuff down into smaller files because you only need to load the files that you actually use. But, at 4,000 lines, it probably won't make too much of a difference.
I'd suggest a solution similar to this
function inc_lib($name)
{
include("/path/to/lib".$name.".lib.php");
}
function inc_class($name)
{
include("/path/to/lib".$name.".class.php");
}