Issue

After upgrading the Mendix Cloud node, the operating system memory usage remains high. For instance, even after upgrading the node from M21 to L21 and increasing the allocated memory from 4GB to 8GB, the OS memory usage still appears elevated. Users are concerned that the memory upgrade did not take effect.

Environment

Mendix Cloud

Cause

The operating system memory usage includes various components such as JVM memory, native memory, metadata, permanent generation, and others. When memory is allocated to the container, the JVM typically claims a significant portion of it, even if not all of it is utilized.

To delve deeper, the JVM memory consists of heap space and unused heap space. The heap is where object data is stored, and once memory is claimed for the object heap, it is not returned while the application is active. A portion of this memory, known as the ‘unused java heap,’ is reserved for quick allocation but remains unused.

When examining OS memory usage, the entire size of JVM including used and unused java heap are included. This means that the application’s node memory will remain elevated while the application is active, depending on the specific application and its infrastructure.

Once processes or user activities are completed, memory will be released through garbage collection, becoming part of the unused Java heap. This behavior explains why OS memory usage remains high even after upgrading. 

Solution/Workaround

This is expected for Mendix Cloud memory usage metrics. Unless there are actual performance issues or memory leaks within the application, the elevated memory usage is normal.

Additional information 

• Memory Usage
• Java memory usage
• Mendix Runtime and Java