How To Fix CSM_VMC065 - Average Frequency of GC Runs for All Virtual Machines

SAP Error Message - Details

• Message type: E = Error

• Message class: CSM_VMC - Messages for VM Container Monitoring

• Message number: 065

• Message text: Average Frequency of GC Runs for All Virtual Machines

What causes this issue?

Each of the active virtual machines in the VM Container has reserved
memory for its Java heap. The size of this memory is bound to specified
limits when the VM is started and cannot be changed at runtime. Once
this memory is used up, the VM activates the garbage collection (GC)
procedure, in which memory allocated but no longer needed is freed up
again. There are two stages to this procedure - partial and full
garbage collection. The partial GC only cleans up dedicated memory areas
and therefore is much quicker than the full GC, and uses less resources.
This partial GC is performed more frequently and is part of normal
operation. The full GC is started when the permanent memory usage
(objects that have survived several partial GCs) exceeds specified
limits. Full GC empties all the objects from the Java heap that are no
longer needed, and therefore reduces the amount of memory occupied to
the smallest possible amount. This process involves a complex analysis
of the Java object references and takes a long time and uses up alot of
VM resources.

System Response

This monitor displays the average frequency of GC runs in all virtual
machines in the VM Container. This figure is usually dominated by the
frequency of the partial GCs, and can have values up to 100 [1/min].

How to fix this error?

To get more information about the Java memory state in the VM Container,
this monitor should always be viewed together with the values of the
full GC rate monitor and with the monitors for the memory usage.
You can find more information about the memory classes in the VM
Container in the online documentation under
<DS:KENO.001560AA0E081DEB91E241270609CAF7>Memory Management in the VM
Container</>.

Procedure for System Administrators

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message CSM_VMC065 - Average Frequency of GC Runs for All Virtual Machines ?

  The SAP error message CSM_VMC065, which pertains to the "Average Frequency of GC Runs for All Virtual Machines," typically relates to performance issues in a Java-based SAP system, particularly in the context of garbage collection (GC) in the Java Virtual Machine (JVM). This error indicates that the frequency of garbage collection runs is higher than expected, which can lead to performance degradation.
  Cause:
  
  High Memory Usage: The application may be consuming more memory than allocated, leading to frequent garbage collection.
  Memory Leaks: There may be memory leaks in the application, causing objects to remain in memory longer than necessary.
  Improper JVM Configuration: The JVM may not be optimally configured for the workload, leading to inefficient memory management.
  Insufficient Heap Size: The heap size allocated to the JVM may be too small for the application's needs.
  High Object Creation Rate: The application may be creating objects at a high rate, leading to frequent GC cycles.
  
  Solution:
  
  Analyze Memory Usage: Use tools like SAP Memory Analyzer (MAT) to analyze memory usage and identify potential memory leaks or high memory consumption areas.
  Optimize JVM Parameters: Adjust JVM parameters such as heap size (-Xms and -Xmx), garbage collection settings, and other performance-related options. For example, consider using the G1 garbage collector if not already in use.
  Increase Heap Size: If the application consistently runs out of memory, consider increasing the heap size allocated to the JVM.
  Code Optimization: Review the application code for inefficiencies, such as unnecessary object creation or holding references to objects longer than needed.
  Monitor GC Logs: Enable and analyze garbage collection logs to understand the frequency and duration of GC events. This can provide insights into how the application is behaving under load.
  Load Testing: Conduct load testing to simulate production-like conditions and identify performance bottlenecks.
  
  Related Information:
  
  SAP Notes: Check for relevant SAP Notes that may provide specific guidance or patches related to this error.
  JVM Documentation: Review the documentation for the specific JVM version being used, as different versions may have different tuning parameters and garbage collection algorithms.
  Performance Monitoring Tools: Utilize performance monitoring tools to keep track of memory usage, CPU load, and other relevant metrics in real-time.
  SAP Community: Engage with the SAP Community for insights and shared experiences from other users who may have encountered similar issues.
  
  By addressing the underlying causes and implementing the suggested solutions, you can mitigate the impact of the CSM_VMC065 error and improve the performance of your SAP system.