How We Optimized Drupal 8 PDF Exports: Handling 600+ Node Reports

The Challenge: Large-Scale PDF Generation in Drupal 8

When a client needed to generate comprehensive PDF reports from hundreds of Drupal nodes, we knew the standard Entity Print module wouldn’t cut it. The requirements were clear:

• Export individual nodes as separate PDFs
• Combine up to 600 nodes into a single, unified PDF report
• Operate within Pantheon’s execution time and memory limits
• Maintain reasonable performance for content editors

Why Standard Solutions Fell Short

Drupal 8’s Entity Print module works well for smaller exports, but it hits significant limitations with larger datasets:

• Memory constraints: Processing 600 nodes at once required nearly 1GB of memory
• Execution timeouts: The process could take up to 2 hours, far exceeding typical web server timeouts
• Server limitations: Pantheon’s platform enforces strict resource limits to ensure stability

Our Solution: Batch Processing with Drush

Phase 1: Parallel PDF Generation

Instead of processing all nodes in a single request, we implemented a batch processing system that:

1. Processes nodes in manageable chunks
2. Generates individual PDFs for each node
3. Tracks progress between batch operations

// Example batch operation callback
function mymodule_generate_pdf_batch_operation($nids, &$context) {
  $node_storage = \Drupal::entityTypeManager()->getStorage('node');
  $nodes = $node_storage->loadMultiple($nids);
  
  foreach ($nodes as $node) {
    // Generate individual PDF for each node
    $pdf = \Drupal::service('entity_print.pdf.engine')->getBlob($node);
    // Save PDF to temporary directory
    file_save_data($pdf, 'temporary://pdf-export/node-' . $node->id() . '.pdf');
  }
  
  $context['results']['processed'] = count($nodes);
  $context['message'] = t('Processed @count nodes', ['@count' => count($nodes)]);
}

Phase 2: PDF Merging with Ghostscript

After generating individual PDFs, we used Ghostscript to merge them efficiently:

# Example Ghostscript merge command
gs -dBATCH -dNOPAUSE -q -sDEVICE=pdfwrite -sOutputFile=combined.pdf node-*.pdf

Performance Results

Our optimized solution delivered impressive results:

• 596 nodes processed in just 14 minutes (vs. 2+ hours previously)
• Memory usage stayed well within Pantheon’s limits
• Final merge operation completed in 9 minutes
• Output: A single 596-page PDF (25MB)

Key Takeaways

1. Batch processing is essential for large Drupal operations
2. Drush provides a more reliable environment for long-running tasks
3. Ghostscript offers efficient PDF merging capabilities
4. Modular architecture allows for flexible deployment (UI or CLI)

Implementation Notes

• The solution works both through Drupal’s UI and Drush
• Progress tracking helps monitor long-running operations
• Temporary file cleanup is handled automatically
• The system gracefully handles failures and can resume interrupted processes

Looking Ahead

This approach can be extended to:

• Scheduled report generation
• Email delivery of completed reports
• Integration with Drupal’s queue system for even larger datasets

Need help with your Drupal performance challenges? Contact our team to discuss how we can optimize your Drupal implementation.