问题
I wanted to take the dump of the Permgen of a application server.
I do not want to use -XX:+TraceClassLoading -XX:+TraceClassUnloading as i do not want to restart the server, Neither i want to use jconsole.
I there any tool like jmap(used to heap dump didnt find any option for permgen) to get the permgen so that i can supply only the pid.
回答1:
jmap -permstat <pid>
is going to produce an output like that :
30337 intern Strings occupying 2746200 bytes.
class_loader classes bytes parent_loader alive? type
<bootstrap> 2031 7253392 null live <internal>
0x517474f0 1 1760 null dead sun/reflect/DelegatingClassLoader@0x43f95d38
0x4f83f670 1 1744 0x4ebfb8e8 dead sun/reflect/DelegatingClassLoader@0x43f95d38
[...]
total = 287 10020 35889952 N/A alive=3, dead=284 N/A
This is not a full dump, but doing that is going to allow you to do some investigation.
I am still looking on how to find more information.
回答2:
It is not possible to 'dump permgen' as it's done for the heap.
In addition to jmap -permstat as others have presented, you can analyze standard heap dump to shed some light on your permanent generation as described in this blog entry: 'The Unknown Generation: Perm'.
Because a heap dump does not really contain a lot of information about perm space, perm problems are difficult to tackle. Recently, I found this great article by Sporar, Sundararajan and Kieviet. The authors shed some light on the permanent generation. Of course, I had to check right away if and how I can use the Eclipse Memory Analyzer to analyze this “unknown” generation. This is what this blog is about.
回答3:
jmap -permstat <pid>
来源：https://stackoverflow.com/questions/4080010/how-to-dump-permgen