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

[Per Liden]

Actually, that seems a bit too restrictive as vm.cds.archived.java.heap 
is only true when G1 is enabled.

So, this is probably even better:

  * @requires vm.cds
  * @requires vm.opt.final.UseCompressedOops
  * @requires vm.opt.final.UseCompressedClassPointers

Updated webrev: http://cr.openjdk.java.net/~pliden/8205702/webrev.2

/Per

On 06/27/2018 10:37 AM, Per Liden wrote:
> Updated webrev, which adjusts the @requires tag, from:
> 
>    @requires vm.cds & vm.gc != "Z"
> 
> to:
> 
>    @requires vm.cds.archived.java.heap
> 
> which I believe is more correct in this case.
> 
> http://cr.openjdk.java.net/~pliden/8205702/webrev.1
> 
> cheers,
> Per
> 
> 
> On 06/27/2018 09:15 AM, Per Liden wrote:
>> Hi Coleen,
>>
>> This doesn't look quite right to me. ZGC already disables 
>> UseCompressedOop and UseCompressedClassPointers, which should be the 
>> indicators that we can't use CDS. The problem is that CDS checks those 
>> flags _before_ the heap has had a change to say they it supports. So 
>> if we just move the call to set_shared_spaces_flags() after the call 
>> to GCConfig::arguments()->initialize() (which should be safe), then 
>> we're all good and you'll get the usual:
>>
>> $ ./build/fastdebug/images/jdk/bin/java -Xshare:dump 
>> -XX:+UnlockExperimentalVMOptions -XX:+UseZGC
>> Error occurred during initialization of VM
>> Cannot dump shared archive when UseCompressedOops or 
>> UseCompressedClassPointers is off.
>>
>> Here's a proposed patch for this, which also adjusts the appropriate 
>> tests for this:
>>
>> http://cr.openjdk.java.net/~pliden/8205702/webrev.0
>>
>> cheers,
>> Per
>>
>> On 06/27/2018 01:09 AM, coleen.phillimore at oracle.com wrote:
>>>
>>> Hi Calvin, thank you for reporting the bug and the code review and 
>>> test code.
>>>
>>> On 6/26/18 5:42 PM, Calvin Cheung wrote:
>>>> Hi Coleen,
>>>>
>>>> The code changes look good.
>>>>
>>>> Since there's a new error message, I'd suggest adding a test to 
>>>> runtime/SharedArchiveFile/SharedArchiveFile.java as follows:
>>>>
>>>> diff --git 
>>>> a/test/hotspot/jtreg/runtime/SharedArchiveFile/SharedArchiveFile.java b/test/hotspot/jtreg/runtime/SharedArchiveFile/SharedArchiveFile.java 
>>>>
>>>> --- 
>>>> a/test/hotspot/jtreg/runtime/SharedArchiveFile/SharedArchiveFile.java
>>>> +++ 
>>>> b/test/hotspot/jtreg/runtime/SharedArchiveFile/SharedArchiveFile.java
>>>> @@ -52,5 +52,13 @@
>>>>                                "-Xshare:on", "-version");
>>>>          out = CDSTestUtils.executeAndLog(pb, "SharedArchiveFile");
>>>>          CDSTestUtils.checkExec(out);
>>>> +
>>>> +        // CDS dumping doesn't work with ZGC
>>>> +        ProcessBuilder pb = 
>>>> ProcessTools.createJavaProcessBuilder(true,
>>>> + "-XX:SharedArchiveFile=./SharedArchiveFile.jsa",
>>>> +                                "-XX:+UseZGC",
>>>> +                                "-Xshare:dump");
>>>> +        out = CDSTestUtils.executeAndLog(pb, "SharedArchiveFile");
>>>> +        CDSTestUtils.checkExecExpectError(out, 1, "DumpSharedSpaces 
>>>> (-Xshare:dump) is not supported with ZGC.");
>>>>      }
>>>>  }
>>>>
>>>> (I haven't tested the above)
>>>
>>> It needed an -XX:+UnlockExperimentalVMOptions as well, and not 
>>> reclare pb.
>>>
>>> open webrev at http://cr.openjdk.java.net/~coleenp/8205702.02/webrev
>>>
>>>>
>>>> Also, I think the new error message should be included in the 
>>>> release notes.
>>>>
>>>
>>> I added the test case and it passes.  I don't think having a release 
>>> note for something that nobody would ever do for an experimental 
>>> option is worth having.   But I can look into the ZGC release notes 
>>> and see if there's something that says CDS is not supported.
>>>
>>> Thanks,
>>> Coleen
>>>> thanks,
>>>> Calvin
>>>>
>>>> On 6/26/18, 2:13 PM, 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
>>>