Understanding and Fixing Memory Usage Benchmarks in Node.js

---

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---

The Problem: Inaccurate Memory Measurements

In an attempt to benchmark memory usage, you may have used the following method to calculate the baseline memory and compare it after creating objects of varying sizes:

[[See Video to Reveal this Text or Code Snippet]]

However, upon running your tests with various array sizes, the memory usage output may not reflect what you expected:

[[See Video to Reveal this Text or Code Snippet]]

The Solution: Controlling for Garbage Collection

To achieve reliable measurement, you need to account for how the garbage collector operates. Here's a more robust approach that ensures you get accurate memory statistics by manually controlling garbage collection (GC).

Step 1: Modify the Memory Usage Function

Update your memoryUsed function to force garbage collection before measuring the memory usage. This can be done as follows:

[[See Video to Reveal this Text or Code Snippet]]

[[See Video to Reveal this Text or Code Snippet]]

Step 3: Run the Benchmark Again

With garbage collection manually triggered, you can rerun your tests. The updated result should reflect a more accurate memory usage corresponding to the size of the objects created.

Expected Results

After implementing these changes, your benchmark results should look like:

[[See Video to Reveal this Text or Code Snippet]]

Observations on Memory Cost

It’s important to note that the memory statistics you're observing provide insight not only into objects but also into the additional overhead of strings and other elements involved in your data structures. The growth of memory usage is often linear when managing properties within shared shapes or hidden classes in JavaScript objects.

Conclusion

Key Takeaways:

Manually trigger garbage collection to improve the accuracy of memory measurements.

Use the --expose-gc flag when running your Node application for better control of memory usage.

Remember to analyze both object properties and underlying string data when evaluating memory usage.