Debugging Slow AEM Performance

Adobe Experience Manager (AEM) is a powerful content management system, widely used by enterprises for its robust features and flexibility. However, authors/users may sometimes experience slowness, which can be intermittent, gradually degrading over time, or consistently slow. This post aims to help diagnose and resolve such performance issues.

How to Diagnose and Fix AEM Performance Issues

Slow performance can stem from various factors, ranging from server configuration, network issues, to inefficient code. Here’s few pointers on how to diagnose and resolve performance issues in AEM.

1. Spotting Where the Issue Lies

First up, we need to zero in on the performance trouble spots.

• Is it happening across the entire platform or specific to certain pages or functionalities?
• Are the slowdowns more pronounced during certain times of the day or under specific load conditions?
• Are users from a particular geographic location experiencing the slowness, or is it widespread?
• Is the performance issue observed by multiple users or isolated to individual experiences?
• Are there specific user actions that trigger the slowness?

2. Examine Server Health

Monitoring your server’s CPU and memory is critical, as high usage levels can lead to a slowdown in AEM. Use CPU profiler to spot any resource-hogging processes and take the necessary steps to mitigate this.

Additionally, disk space should be on your checklist. AEM operates best when it’s not cramped for space, particularly where it stores its repository.

When assessing your server, consider the following:

• Do you notice a lag as soon as the system boots up, or does it become slower as time goes on?
• Compare the live CPU, memory, and disk usage statistics to what you would normally expect.
• Look out for any odd processes or services that are using more resources than they should.
• Make sure that the server’s hardware and setup are current and can handle the load being placed on them.

3. Validate Configurations and Maintenance

Keep an eye on your repository size because if it gets too big, it will drag down AEM’s speed. Make it a habit to clean out old content and do regular maintenance like purging old versions, workflows, audit logs etc.

Also, make sure your dispatcher cache is set up right. It’s there to help lighten the load on your AEM servers by storing cacheable content properly and ensuring that cache flush operations are running efficiently.

During your routine checks, you should be asking:

• When did you last run maintenance tasks such as Garbage collection, Revision cleanup (compaction) etc?
• Is your dispatcher cache working like it’s supposed to, with proper hit ratios and timely invalidation of old data?

4. Analyze Network Performance

Network issues can also contribute to slowness. Use tools like Ping or Traceroute to check for network latency. Ensure the network connection between the AEM servers and dispatcher is optimal.

When assessing your server, consider the following:

• What is the current network latency, and how does it compare to normal conditions?
• Are there any recent changes in network topology or configurations that might affect performance?
• Is the bandwidth sufficient for the volume of traffic, especially during peak usage?
• Could network hardware or firewall settings be contributing to the slowdown?

5. Validate Code

In this crucial step, we dig into the code that could be at the heart of AEM performance issues. By asking the right questions, we can identify inefficiencies and optimize the system for smoother operation.

Consider these queries when diagnosing performance problems:

• Asset Handling: Is there a noticeable delay when you upload or process assets, or during workflow execution? Link to Asset Performance Tuning
• System Updates: Have recent updates or deployments been made that might align with the timing of the slowdown?
• Query Performance: Are certain queries dragging their feet? Could the presence of Traversal warnings indicate a need for index optimization? Link to Best Practices
• Error Handling Efficiency: Is there error handling in your scripts that’s causing unnecessary processing, such as frequent retries or complex fallbacks?
• Long Processes: Are there long-running scripts or processes that might be hogging system resources?
• Frontend Execution: Does the frontend code run efficiently, or is there room to optimize it to cut down on rendering time and speed up the user experience?
• Data Access: When fetching data from the repository or external sources, are these methods introducing lag time?
• Page Load: Are pages with lots of content and media taking too long to load? Could unoptimized images or media be to blame?
• Unoptimized Client library: Are the client libraries consolidate, minified and ached? Is CSS in the head, JavaScript at the end? Refer to “Client-side performance” on link for strategies
• Third-party Services: Are integrated external services slowing things down, and if so, how are they integrated and managed? Refer to Building Robust AEM Integration for guidelines.
• Code Synchronization: Could issues with thread management or deadlocks in your custom code be impacting performance? Refer to AEM Thread Dump Analysis

6. Implementing Best Practices

After pinpointing the problem, consult the appropriate best practices documentation. You will discover several methods to refine your system. Choose the approach that best fits your needs.

General issues leading to temporary, gradual, or consistent performance problems

Next, let’s categorize the issues. What causes them and how to address them

Intermittent Slow downs

• Overloaded Server: If your server is hit with more than it can handle at times, this can lead to temporary slow periods.
  • Keep an eye on the server’s workload with AEM’s Health Check or external tools like New Relic, and upgrade your resources or streamline processes if necessary.
• Garbage Collection Processes: If you encounter extended garbage collection pauses, focus on refining your application code to consume less memory. In most cases, addressing garbage collection issues effectively entails optimizing the application itself rather than adjusting JVM settings.
• Network Latency: Temporary network issues can slow down response times.
  • Use network monitoring tools to identify and resolve any latency issues.
• Asset Processing: When you upload a lot of assets at once, it can be a lot for AEM to handle.
  • Shift large-scale processing/bulk-upload during less active hours to keep your main system running smoothly. Link to Asset Performance Tuning

Gradual Performance Declines

• Repository Growth: As the AEM repository grows, it can slow down if not managed properly.
  • Regularly archive or delete unused content and implement regular maintenance tasks to compact and clean up the repository.
• Long-lived Sessions: Sessions that are not properly closed can consume memory and degrade system performance over time.
  • Ensure that all sessions are closed appropriately in the code after their operation is completed. Utilize try-with-resources in Java for automatic session management.
• Unoptimized Dispatcher Cache Flush: Inefficient cache flushing can cause the cache to be cleared too frequently, leading to performance issues.
  • Ensure that cache flush is optimized to balance freshness with performance.
• Insufficient Resources: As usage grows, the initially allocated resources may become insufficient.
  • Monitor resource utilization over time. Scale up resources or optimize the application to handle increased load efficiently.
• Sling Jobs:
  • Review Queues: Regularly check the queue configurations and adjust the number of concurrent jobs to avoid overloading the system.
  • Monitor Execution: Track execution times and frequency to ensure jobs complete efficiently and don’t clog the system.
  • Error Handling: Implement proper error handling and retry mechanisms to prevent excessive resource consumption.
• Workflows:
  • Analyze Models: Examine workflow models for inefficiencies and ensure they are streamlined and optimized for performance.
  • Monitor Instances: Keep an eye on the number of active workflow instances, especially long-running ones, which can hog system resources.
  • Optimize Steps: Evaluate each step of the workflow for performance; remove unnecessary steps and optimize resource-intensive processes.
• HTTP Connections:
  • Connection Pooling: Ensure the HTTP connection pool size is optimized to handle the load without exhausting resources.
  • Timeout Settings: Configure appropriate timeout settings to avoid holding resources for stalled connections.
  • Caching Strategy: Use caching for HTTP responses when feasible to reduce the number of outbound connections.
• Event Handlers:
  • Optimize Listeners: Ensure event handlers and listeners are not performing intensive operations that can slow down the system.
  • Selective Listening: Use filters to listen to only the necessary events and avoid unnecessary execution of event handlers.

Constant Slowness

• Client Library Management: Unoptimized client libraries (CSS/JS) can increase page load times.
  • Cache JavaScript and CSS for extended durations
  • Merge them into fewer files.
  • Minimize the libraries to reduce their size.
  • Place CSS includes within the HTML head tag to prevent page flickering and repaint after loading.
  • Position JavaScript script includes at the end of the body tag or apply the async script attribute, enabling the browser to load JavaScript files simultaneously during page rendering.

• Image Optimization Debugging: Use tools like Google’s PageSpeed Insights to identify unoptimized images. Adjust images to be responsive, ensuring they fit the screen they are being viewed on without losing quality or causing delays. Consider the following strategies:
  • Utilize AEM’s Core Image Component: This component automatically delivers adaptive images. It ensures that the images served are responsive to the viewing device, optimizing for both screen size and resolution.
  • Leverage Dynamic Media for Smart Cropping and Smart Imaging:
    • Smart Imaging provides better image delivery performance by automatically optimizing image file size based on client browser in use, the device display & network conditions. 
    • Smart cropping features can focus on the most important part of an image, while various image renditions allow for serving the correct image size based on the user’s device.
  • Implement Web-Optimized Image Delivery: Take advantage of modern image formats (like WebP) that maintain visual quality at lower file sizes. This approach helps in reducing the bandwidth needed for images, thus improving the page load times.

• Indexing and Queries: Inefficient indexes can slow down query execution, affecting overall performance. Regularly review and optimize AEM query indexes. Identify slow queries through the Query Performance tool and adjust or create custom indexes as needed.

Broad Optimization Techniques

• Browser and CDN Cache: Caching is crucial for reducing server load and improving response times. Configure browser cache policies for static assets and use a Content Delivery Network (CDN) to cache content closer to the user. This reduces latency and speeds up content delivery.
• Leveraging SDI for Dynamic Content: Sling Dynamic Include (SDI) enables dynamic loading of content while maintaining the cacheability of the surrounding page. This is particularly useful for personalizing/dynamic content without sacrificing cache efficiency.

Wrapping up, a methodical approach is vital for pinpointing and resolving AEM performance issues. Consistent monitoring and proactive optimization are the keys to a well-running AEM instance.