Why is my PHP script stopping when generating thumbnails? – CPanel

The issue is definitely either a timeout or resource scarcity (memory or something like that). This article shows ImageMagick causing 315.03 MB memory usage per image and 47% CPU usage. That can compound/leak if you’re cycling through images in the processor in a foreach loop. Image transformations can be expensive on server resources. It might also be a problem with one of your image files or some other oddity.

Ajax it

A solution to any of these problems is to process these in small batches. Create a simple ajax/php loop – using an html.php page for the ajax and a separate file for the processing, like this:

thumb-display.php

<script>
const batchSize = 5; // number of images per send
function doThumb(nextIndex) {
    $.ajax({
      url: "thumb-process.php",
      method: "post",
      data: {nextIndex: nextIndex, batchSize: batchSize},
      dataType: "json"
    }).done(function(response) {
      if (response.thumbs) {
         response.thumbs.forEach( th => $('.thumbs').append('<img alt="" src="'+th+'" />') ) ;
      }
      if (response.finished) alert('finished')
      else {
        console.log('processed batch index #' + (nextIndex-batchSize + ' - ' + nextIndex);
        nextIndex += batchSize;
        setTimeout(() => { doThumb(nextIndex) }, 1000);
      }
    }).error(function (e) {
       console.error('Error happened on batch index #' + (nextIndex-batchSize + ' - ' + nextIndex, ' - details: ', e);
    })
    ;
}

$(document).ready(() => { doThumb(0); } )
</script>


<div class='thumb-list'></div>

thumb-process.php

function GenerateThumbnail($src, $dest)
{
    $Imagick = new Imagick($src);
    $bigWidth = $Imagick->getImageWidth();
    $bigHeight = $Imagick->getImageHeight();
    $scalingFactor = 230 / $bigWidth;
    $newheight = $bigHeight * $scalingFactor;
    $Imagick->thumbnailImage(230,$newheight,true,true);
    $Imagick->writeImage($dest);
    $Imagick->clear();
    return true;    
}

// Get list of files in upload dir
$arrImageFiles = scandir(UPLOAD_DIR);

// Remove non-images
$key = array_search('.', $arrImageFiles);
if ($key !== false) 
    unset($arrImageFiles[$key]);

$key = array_search('..', $arrImageFiles);
if ($key !== false) 
    unset($arrImageFiles[$key]);

$key = array_search('.ftpquota', $arrImageFiles);
if ($key !== false) 
    unset($arrImageFiles[$key]);

$key = array_search('thumbs', $arrImageFiles);
if ($key !== false) 
    unset($arrImageFiles[$key]);
$nextIndex = $_POST['nextIndex'];
$max = min( ($nextIndex + $_POST['batchSize']), count($arrImageFiles)-1);
$thumbs = [];
while($nextIndex < $max){    
  $imageFile = $arrImageFiles[$nextIndex ];
  $thumbFullPath =  THUMB_DIR . "th_" . $imageFile;
  $imageFullPath = UPLOAD_DIR . $imageFile;
  if (!$imageFile) {
    $output = array('finished' => 1) ;
    die(json_encode($output));
  }
  if (! file_exists($thumbFullPath))  {           
    GenerateThumbnail($imageFullPath, $thumbFullPath);
  }
  $thumbs[]= $thumbFullPath ;
  $nextIndex++;
}

$output = array('thumbs' => $thumbs);
  
if ($nextIndex >= count($arrImageFiles)-1) $output['finished'] = 1 ;

echo json_encode($output);

.. and just sit back and watch your console. If you get a timeout or other error, you’ll see the nextIndex it choked on, and you can reload your page with that number as a starting index instead of 0.

Of course you could gather all the file paths in an array in thumb-display.php and send each filepath through ajax (so as not to have to recount all files in that path each time), but personally I feel better about sending a number through post rather than an image path. Let me know if you’d rather have a big array of filepaths to send instead of an index#.