What is VMware Heap Size? How to Clear VMware Heap Size ?

Heap size in a VMware infrastructure refers to a portion of memory used to manage virtual machines and VMware-specific operations. The heap is dynamically allocated memory that can be released back to the operating system. It is used to store runtime data required for virtual machines, applications, and system processes.

Factors Increasing Heap Usage:

Virtual Machine Density: More VMs increase heap usage.
Application Requirements: Applications with high memory needs can raise heap usage.
Memory Leaks: Leaks in applications or processes can consume heap memory.
System and Service Updates: Updates may temporarily increase heap usage.
Configuration Changes: Adjustments in settings can impact heap usage.

Monitoring heap usage is crucial to prevent performance issues and maintain system health.

Methods to Clear VMware Heap Size:

You might need to clear the heap space on your VMware ESXi servers. Usually, the heap space is automatically managed to enhance the functionality of ESXi servers and prevent memory leaks. However, manual intervention might be necessary in certain situations. Here are some methods to consider:

Restart the ESXi Host: This is the simplest and most effective method if possible. It clears all memory and resets the heap space.
Restart Services: If restarting the host is not an option, you can clear the heap space by restarting key services. For example, use the commands /etc/init.d/hostd restart and /etc/init.d/vpxa restart to restart the management network service.
Check Advanced Settings: Some advanced settings, like Config.HostAgent.plugins.solo.enableMob, can affect heap size. Adjusting these settings as specified in VMware’s knowledge base might resolve issues.
Manage Memory Resources: Identify and address virtual machines or applications causing high memory usage to indirectly reduce heap usage.
Check Log Files: Log files in the /var/log directory, especially vmkernel.log and hostd.log, can help identify and troubleshoot heap issues.