RFR(s): 8067187: -XX:MaxMetaspaceSize=20m -Xshare:dump caused JVM to crash

[Stefan Karlsson]

Hi Calvin,

On 2014-12-12 21:42, Calvin Cheung wrote:
> JBS: https://bugs.openjdk.java.net/browse/JDK-8067187
>
> This fix is to add a check on the MaxMetaspaceSize when performing CDS 
> archive dumping.
>
> With the fix, instead of a crash, it will print and error message like 
> the following and exit:
>
> Java HotSpot(TM) 64-Bit Server VM warning:
> The MaxMetaspaceSize of 20971520 bytes is not large enough.
> Either don't specify the -XX:MaxMetaspaceSize=<size>
> or increase the size to at least 33554432.
>
> Tested manually via command line and jtreg test on the new test.
>
> webrev: http://cr.openjdk.java.net/~ccheung/8067187/webrev/

Please, don't add this check and side-effect deep down in 
MetaspaceGC::can_expand. I think it would be better if you move this 
check further up in the call chain. Maybe Metaspace::initialize would be 
a good place. We already do CDS specific checks in that method, for example:
assert(!DumpSharedSpaces || new_chunk != NULL, "should have enough space 
for both chunks");

Thanks,
StefanK

>
> thanks,
> Calvin