topic Re: Alfresco RAN usage over -Xmx in Alfresco Archive

Alfresco RAN usage over -Xmx

audriusp — Thu, 19 May 2016 07:36:15 GMT

Hello,we have a limit of -Xmx24158M, but after some usage it reports using around 38 Gb?Where is the catch?

Re: Alfresco RAN usage over -Xmx

afaust — Thu, 19 May 2016 08:03:01 GMT

For any Java application that is active, there are multiple memory areas that the application manages. One of those is the heap which you can configure/limit via -Xmx. Others are e.g. code store (previously often referenced as PermGen), stack, constant pools… Look at <a href="https://docs.oracle.com/javase/specs/jvms/se7/html/jvms-2.html">the structure of Java virtual machine</a> to learn more.
Long story short: -Xmx does not limit the total amount of memory a Java process can take.

Re: Alfresco RAN usage over -Xmx

audriusp — Thu, 19 May 2016 08:24:15 GMT

So, is there an easy way to limit RAm usage for alfresco?

Re: Alfresco RAN usage over -Xmx

afaust — Fri, 20 May 2016 07:42:30 GMT

No, there is no "easy" way to limit RAM usage, because any "easy" way would gloss over application requirements and end up in a horrible performance scenario. You can limit the RAM usage technically, but you need to understand what which memory area does, how it is used by Alfresco over time and how it affects performance.

VMWare once (a long time ago) posted a <a href="http://blogs.vmware.com/apps/2011/06/taking-a-closer-look-at-sizing-the-java-process.html">blog post</a> about limiting the memory for the entire Java process.
Again: Be very, very careful when trying to hard limit the memory…

Re: Alfresco RAN usage over -Xmx

audriusp — Fri, 20 May 2016 13:23:20 GMT

Thanks for the response