Need Clarification on memoryMaxUsage and memoryMinStdev

[Former Community Member]

Hi,

We got following error on our author instance after which the server shuts down.

13.08.2015 18:41:45.057 *ERROR* [jackrabbit-pool-10] com.day.crx.core.ResourceMonitor stdev of memory usage samples is 0.0, which is lower than 1. shutting down

13.08.2015 18:41:45.066 *ERROR* [ClosingThread] com.day.crx.core.ResourceMonitor More than 98 usage and stdev less than 1.

Need to know more about how standard deviation of memory usage is calculated here, and why this value should be more than 2 (default value)?

How can we analyze this OutOfMemory situation?

[Opkar_Gill]

Have a look at this article: https://helpx.adobe.com/experience-manager/kb/AnalyzeMemoryProblems.html

What version of AEM are you running? How much system memory do you have? How much memory have you allocated to AEM? Can you share your start parameters?

Memory problems should not normally be an issue, could there be memory leaks in your code? Heap dumps help you investigate this. 

Regards,

Opkar

[Opkar_Gill]

If you are using AEM5.6 here is an article for Monitoring Memory Usage: https://docs.adobe.com/docs/en/cq/5-6-1/core/administering/monitor-diskspace-memory.html

[Former Community Member]

Have gone through all the articles. But no success. Need to know how this what stdev <1 signify ?

We are using AEM 5.6.1

8 GB of space have been allocated to AEM.

[Sham_HC · Accepted solution]

stddev is Minimum standard deviation. The low memory monitor takes 100 memory samples per second and uses these to calculate the standard deviation from the average memory consumption over time.   All the points provided from opkar should help & answer your query. If you are not able to follow those file a support ticket so that support guy can help to understand better.

[1]  https://helpx.adobe.com/experience-manager/kb/crx-disk-and-memory-monitoring-shutdown-too-aggresivel...

[Opkar_Gill]

How much physical memory does your machine have?

Have you enabled -XX:+HeapDumpOnOutOfMemoryError

You really need to analyse your application code: http://cq-ops.tumblr.com/post/58841321992/how-to-determine-the-cause-of-a-cq-memory-leak

[Former Community Member]

@ Opkar We were having -XX:+HeapDumpOnOutOfMemoryError parameter in the start script, but later we removed that.

@ Sham HC We have implemented the resolution mentioned in the article. But then also this condition occur. Is stdev < 1 directly related to memory leaks?  

[Former Community Member]

Physical memory is 24GB

[Opkar_Gill]

Your instance shouldn't be shutting down with that much memory, it is either your codebase or some actions being performed on your system.

Are there specific actions you are doing when you run out of memory: Large DAM content uploads?

Do you have "-XX:+HeapDumpOnOutOfMemoryError", if so what did it tell you? Have you already created heap dumps and analysed them?