RFR (XS) 8205702: assert(UseCompressedClassPointers) failed in universe.hpp

[Per Liden]

Hi Jiangli,

On 06/27/2018 06:16 PM, Jiangli Zhou wrote:
> Hi Per,
> 
> Here is the tmpfs I ran into. Setting -XX:ZPath=/run/shm seems to work.

Ok, good!

Setting -XX:ZPath is needed when running on Linux kernels < 3.17 _and_ 
there are multiple tmpfs filesystems mounted, in which case ZGC needs 
some guidance on which one to use. When running on kernels >= 3.17 we 
instead use memfd_create() to get a tmpfs file handle, and -XX:ZPath is 
never needed.

cheers,
Per

> 
> [0.013s][error][gc,init] More than one tmpfs filesystem found:
> [0.013s][error][gc,init]   /run/lock
> [0.013s][error][gc,init]   /run/shm
> [0.013s][error][gc,init] Use -XX:ZPath to specify the path to a tmpfs 
> filesystem
> Error: Could not create the Java Virtual Machine.
> Error: A fatal exception has occurred. Program will exit.
> 
> 
> Thanks,
> Jiangli
> 
>> On Jun 27, 2018, at 12:33 AM, Per Liden <per.liden at oracle.com 
>> <mailto:per.liden at oracle.com>> wrote:
>>
>> On 06/26/2018 11:57 PM, Jiangli Zhou wrote:
>>> Hi Coleen,
>>> This looks good.
>>> Should we also disable UseSharedSpaces at runtime for ZGC in case an 
>>> archive was dumped using a different GC algorithm? I ran into tmpfs 
>>> error when trying to run with ZGC, so I couldn’t double check for 
>>> that case...
>>
>> What kind of tmpfs errors? I would like to know if we have a bug 
>> somewhere or if it's user error.
>>
>> /Per
>>
>>> Thanks,
>>> Jiangli
>>>> On Jun 26, 2018, at 2:13 PM, coleen.phillimore at oracle.com 
>>>> <mailto:coleen.phillimore at oracle.com> wrote:
>>>>
>>>> Summary: Disable CDS with ZGC
>>>>
>>>> Tested with:
>>>> java -XX:+UnlockExperimentalVMOptions -XX:+UseZGC -Xshare:dump
>>>> java -XX:+UnlockExperimentalOptions -XX:+UseZGC -Xshare:on -version
>>>>
>>>> open webrev at http://cr.openjdk.java.net/~coleenp/8205702.01/webrev
>>>> bug link https://bugs.openjdk.java.net/browse/JDK-8205702
>>>>
>>>> Thanks,
>>>> Coleen
>