Availability of Node Diagnostics

_posts/2024-01-05-Diagnose-Tools-for-NodeJs-Linux-apps.md

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+---
+title: "General availability of Diagnostics tools for App Service on Linux Node.js apps"
+author_name: "Amit Kumar, Puneet Gupta, Tulika Chaudharie"
+---
+
+We are pleased to announce the public availability of Diagnostic tools for App Services Linux for Node.js apps. With this capability, we now offer built-in support for collecting deep diagnostic artifacts that can help you debug application code issues. These artifacts include memory dumps and profiler traces. These tools empower developers to diagnose a variety of Node.js code scenarios on Linux including:
+
+- High memory
+- High CPU
+
+The experience uses [V8 sample-based profiler](https://v8.dev/docs/profile) to collect diagnostic traces/snapshots to identify if application code is contributing to the problem.
+
+## Collection in Diagnose and Solve
+
+To access these new capabilities on your .NET Core apps hosted in Linux, navigate to the **Diagnose and Solve** Blade > **Diagnostics Tools** and select either **Collect Node Heap Dump** or **Collect Node CPU Profiler**.
+
+![Linux Diagnostic Tools]({{site.baseurl}}/media/2024/01/node-diagnostics.jpg)
+
+## Collection in Kudu
+
+The [Kudu console](https://docs.microsoft.com/azure/app-service/resources-kudu) for Linux app services has been updated to include new collection options for memory dumps and profiles on the Process Explorer page.
+
+To navigate to this new Kudu experience use the following (update <**mysite**> with your app name): https://<**mysite**>.scm.azurewebsites.net/**newui** to check out the new experience.
+
+![Process Explorer in Kudu]({{site.baseurl}}/media/2024/01/node-process-explorer.jpg)
+
+When you select the *Process Explorer* page, you can identify the process you want to debug. Use the drop-downs to select the type of memory dump and click **Collect Dump**. Alternatively, you can select the length of a profile from the drop-down and click **Start Profiling**.
+
+## Analyzing a heapsnapshot for Memory Issues
+
+Heap dumps are created using the extension *.heapsnapshot. Once the dump has been created, you will get a link to download it on your local machine. You can analyze the dump using any Chromium browser.
+
+Since Chrome and Edge use the same Javascript runtime (V8 engine), heap snapshots can be read using Chrome or Edge DevTools for Node.\
+**Chrome**: Navigate in Chrome Browser and type ``chrome://inspect/``, then click on **Open dedicated DevTools for Node**\
+**Edge**: Navigate in Chrome Browser and type ``edge://inspect/``, then click on **Open dedicated DevTools for Node**
+
+You can chose the Memory tab and load a Heap Snapshot here for analysis. You will find several columns, the most important ones are **Shallow Size** and **Retained Size**.
+
+ > **Shallow Size**: This is the size of memory that is held by the object itself. Usually, only arrays and strings can have a significant shallow size.\
+ > **Retained Size**: This is the size of memory that is freed once the object itself is deleted due it becoming unreachable from GC roots. Held by object implicitly.
+
+You will be looking for the highest percentage in Retained Size comparing as well with Shallow Size.
+
+![Heap snapshot]({{site.baseurl}}/media/2024/01/heapsnapshot.jpg)
+
+More information on how to analyze heapsnapshot dumps in Chromium browsers can be found here - [Chrome - Devtools - Heapsnapshot - Reference](https://developer.chrome.com/docs/devtools/memory-problems/heap-snapshots/).
+
+## Analyzing a cpuprofile for High CPU Issues
+
+Profiler traces are created using the extension *.cpuprofile. Once the trace has been created, you will get a link to download it on your local machine. You can analyze the trace using any Chromium browser.
+
+**Chrome**: Navigate in Chrome Browser and type ``chrome://inspect/``, then click on **Open dedicated DevTools for Node**\
+**Edge**: Navigate in Chrome Browser and type ``edge://inspect/``, then click on **Open dedicated DevTools for Node**
+
+Chose the Performance tab and you can drag and drop your trace here.
+
+![CPU Profile]({{site.baseurl}}/media/2024/01/node-cpu-profile.jpg)
+
+You can use different views like Call Tree or Bottom-Up. You can also zoom into any of the frames to get more detailed information.
+
+## Conclusion
+
+Summing up, within Azure App Service, we're dedicated to consistently enhancing the in-built diagnostic experience, providing an extensive array of tools that empower you to meticulously analyze and troubleshoot the health of your production applications.