WLST to check the PermGen usage - weblogic

Question

I would like to get the Max Perm Gen and Usage of a server in WL Domain using WLST.
SO far I was able to see it's possible to get the information from JMX, mBean.
The mBean location is "java.lang:Location=Server1,name=PS Perm Gen,type=MemoryPool"
I tried below code but it doesn't seem working.
testObject=ObjectName('java.lang:Location=Server1,name=PS Perm Gen,type=MemoryPool')
Or Trying below code didn't work either.
testBean=getMBean('javax.management.openmbean.CompositeData:Location=Server1,name=Usage,type=PS Perm Gen')
for item in testBean:
print item.getKey() + ':' + item.getValue()
Please help.
Update: -------------------------------------------------
Thanks for the quick reply. There's no WLST code to share in related to my topic yet because I'm trying to explore the possibility out of my search.
Basically, I'm trying to check the available Perm Gen size within WLST run before deploying an artefact to a WL managed server.
This is because WebLogic is not releasing the undeployed artefact's non-heap memory space out of WL managed server and if you keep doing deployment/undeployment without recycling, the WL managed server will eventually throw OOME of Perm Gen space.
We are trying the service outage as minimum and keeping the WL managed server up and running as long as possible.
I've searched everywhere about the WLST mBean tree location to get the non-heap memory status but failed.
But if you use JManage, you can get non-heap memory status through mBean object "java.lang:Location=Server1,name=PS Perm Gen,type=MemoryPool".
It will show like below in JManage:
Object Name java.lang:Location=Server1,name=PS Perm Gen,type=MemoryPool
Class Name sun.management.MemoryPoolImpl
Description Information on the management interface of the MBean
Configured Name Add to Application
So I was wondering why is it not possible to extract the mBean info from WLST if the mBean is there? So I'm trying to get help about anyone who had similar experience/situation.

Answer 1

I have found that you can connect to a managed server and then use something like this:
permObjectName=ObjectName('java.lang:type=MemoryPool,name=PS Perm Gen')
usoPerm=mbs.getAttribute(permObjectName,'Usage')
usoPerm.get('max') #Returns MaxPermSize in bytes
usoPerm.get('used') #Returns used Perm Space in bytes
However, I have tested this in several servers and it doesn't always work because the MBeanServer (mbs) is not able to 'see' the "java.lang" mbean tree.

Answer 2

Weblogic has different mbean hierarchies for different purposes. It considers all non-weblogic mbeans as "custom", and as such they reside in the "custom" tree.
https://docs.oracle.com/cd/E24329_01/web.1211/e24415/understandwls.htm#JMXCU239
To get the permgen usage of the machine you are connected to:
cd('custom:/java.lang/java.lang:type=MemoryPool,name=PS Perm Gen')
permgen=get("Usage").get("used")
If you are connected to a domain admin and want to get the information for a different server:
cd('domainCustom:/java.lang/java.lang:Location='+servername+',name=PS Perm Gen,type=MemoryPool')
permgen=get("Usage").get("used")