RFR(XS): 8065050: vm crashes during CDS dump when very small SharedMiscDataSize is specified

Jiangli Zhou jiangli.zhou at oracle.com
Wed Dec 3 22:55:05 UTC 2014

Hi Calvin,

It's better to define 12M and 16M as enums in metaspaceShared.hpp now 
they are referenced in more than one place.

I also have some questions. The 12M/16M are not introduced by this 
change, do you know why those values were chosen as the default RO and 
RW sizes? Now we require both spaces have to be at lease 12M on 32-bit 
machines and 16M on 64-bit machine, is it a reasonable requirement? 
What's the minimum size requirement for the RO and RW spaces with the 
default classlist?


On 12/01/2014 12:10 PM, Calvin Cheung wrote:
> JBS: https://bugs.openjdk.java.net/browse/JDK-8065050
> Adding more checks on the SharedMiscDataSize, ShareReadOnlySize, and 
> SharedReadWriteSize.
> For the SharedMiscDataSize, it is based on 
> MetaspaceShared::generate_vtable_methods(). Similar to what was done 
> for the SharedMiscCodeSize.
> For the ShareReadOnlySize and SharedReadWriteSize, I'm checking if 
> they are at least the default size.
> I think it's reasonable to enforce the ro and rw sizes to be at least 
> the default size. A default dump of CDS archive requires >8M of ro 
> space and >11M of rw space.
> webrev:
>     http://cr.openjdk.java.net/~ccheung/8065050/webrev/
> tests:
>     ran the testcase via jtreg on linux_x64 and windows_x64
>     JPRT
> thanks,
> Calvin

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