[jmm-dev] official docs about metaspace

Andrew Dinn adinn at redhat.com
Thu Sep 26 08:58:24 UTC 2019

On 25/09/2019 17:52, Andrew Haley wrote:
> On 9/25/19 11:47 AM, 刘波 wrote:
>> I want to know what's metaspace? what's it stores? how it's working? where can I find docs about metaspace?
>> openjdk website search "metaspace" got lots of messages, does anyone know the official docs about metaspace, or any docs about it?
> Not really. It's an internal detail of the virtual machine.

Briefly, Metaspace is the area of memory where the JVM stores 
information that tracks the internal state of the loaded class base and 
related interpreter and JIT compiler information.

I am not aware of any official OpenJDK project documentation that 
explains what Metaspace is and how it is managed. I gave a talk at 
FOSDEM 2018 that gives some details of what information is stored in 
metaspace and how you can use tools like jcmd to measure the amount of 
storage used:


The talk is based on 4 articles that provide a more full explanation. 
PDFs of those articles are available from my github space:



Andrew Dinn
Senior Principal Software Engineer
Red Hat UK Ltd
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