CODEWITHSUNDEEP
phpperformanceimage
Dimen Shaw
Dimen Shaw

Reputation: 35

PHP Script takes almost 15 seconds to load

I've written a PHP script that iterates through a given folder, extracts all the images from there and displays them on an HTML page (as tags). The size of the page is about 14 KB, but it takes the page almost 15 seconds.

Here's the code:

function displayGallery( $gallery, $rel, $first_image ) {
    $prefix = "http://www.example.com/";
    $path_to_gallery = "gallery_albums/" . $gallery . "/";
    $handler = opendir( $path_to_gallery ); //opens directory
    while ( ( $file = readdir( $handler ) ) !== false ) { 
        if ( strcmp( $file, "." ) != 0 && strcmp( $file, ".." ) !=0 ) { 
            //check for "." and ".." files
            if ( isImage( $prefix . $path_to_gallery . $file ) ) {
                echo '<a href="' . $path_to_gallery . $file . '"></a>';
            } 
        }
    }
    closedir( $handler ); //closes directory
}

function isImage($image_file) {
  if (getimagesize($image_file)!==false) {
    return true;
  } else {
    return false;
  }
}

I looked at other posts, but most of them deal with SQL queries, and that's not my case.

Any suggestions how to optimize this?

Upvotes: 2

Views: 666

Answers (5)

Laith Shadeed
Laith Shadeed

Reputation: 4311

getimagesize is the problem, it took 99.1% of the script time.

Version #1 - Orignal case enter image description here

Version #2 - If you really need to use getimagesize with URL (http://). Then a faster alternative, found in http://www.php.net/manual/en/function.getimagesize.php#88793 . It reads only the X first bytes of the image. XHProf shows it is x10 faster. Another ideas also could be using curl multi for parallel download https://stackoverflow.com/search?q=getimagesize+alternative

enter image description here

Version #3 - I think this is the best suitable for your case is to open files as normal files systems without (http://). This is even x100 faster per Xhprof enter image description here

Upvotes: 0

Blind Fish
Blind Fish

Reputation: 998

An out of left field suggestion here. You don't state how you are clocking the execution time. If you are clocking it in the browser, as in taking 15 seconds to load the page from a link, the problem could have nothing at all to do with your script. I have seen people in the past create similar pages trying to use images as tags, and they take forever to load because even though they are displaying the image at thumbnail size or smaller, the image itself is still 800 x 600 or something. I know it sounds daft, but make sure that you are not just displaying large images in a small size. It would be perfectly reasonable for a script to require 15 seconds to load and display 76 800 x 600 jpegs.

Upvotes: 1

evan
evan

Reputation: 12535

My assumption is that isImage is the problem. I've never seen it before. Why not just check for particular file extensions? That's pretty quick.
Update: You might also try switching to use exif_imagetype() which is likely faster than getimagesize() Putting that check into the top function is also going to be faster. Neither of those functions was meant to be done over a web connection - avoid that altogether. Best to stick with the file extension.

Do you not already have access to the files directly? Every time you look something up over the web, it's going to take a while - you need to wait for the entire file to download. Look up the files directly on your system.

Use scandir to get all the filenames at once into an array and walk through them. That will likely speed things up as I assume there won't be a back and forth to get things individually.

Instead of doing strcmp for . and .. just do $file != '.' && $file != '..'

Also, the speed is going to depend on the number of files being returned, if there are a lot it's going to be slow. The OS can slow down with too many files in a directory as well. You're looping over all files and directories, not just images so that's the number that counts, not just the images.

Upvotes: 0

shomeax
shomeax

Reputation: 865

I suppose that's because you've added $prefix in the isImage invokation. That way this function actually downloads all your images directly from your webserver instead of looking them up locally.

you may use use getimagesize(), it issues E_NOTICE and returns FALSE when file is not a known image type.

Upvotes: 1

Trott
Trott

Reputation: 70075

You can use a PHP profiler like http://xdebug.org/docs/profiler to find what part of the script is taking forever to run. It might be overkill for this issue, but long-term you may be glad you took the time now to set it up.

Upvotes: 1

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