RFR: 8170395: Metaspace initialization queries the wrong chunk freelist

[Stefan Karlsson]

Thanks, Mikael!

StefanK

On 2016-11-29 11:53, Mikael Gerdin wrote:
> Hi Stefan,
>
> On 2016-11-28 22:06, Stefan Karlsson wrote:
>> Hi again,
>>
>> This set of patches resolve some of the comments given by Mikael and
>> Thomas:
>>
>> Entire patch:
>>  http://cr.openjdk.java.net/~stefank/8170395/webrev.02
>
> Looks good!
> /Mikael
>
>>
>> Delta patches:
>>  http://cr.openjdk.java.net/~stefank/8170395/webrev.02.01.verify_global_initialization
>>
>>
>>  http://cr.openjdk.java.net/~stefank/8170395/webrev.02.02.revert_enum
>>  http://cr.openjdk.java.net/~stefank/8170395/webrev.02.03.unused_parameter
>>
>>
>> I consider pushing the last patch as a separate changeset.
>>
>> This is the entire patch without the unused_parameter patch:
>>  http://cr.openjdk.java.net/~stefank/8170395/webrev.02.01-02
>>
>> Thanks,
>> StefanK
>>
>> On 2016-11-28 14:52, Stefan Karlsson wrote:
>>> Hi all,
>>>
>>> Please, review this patch to fix metaspace initialization.
>>>
>>> http://cr.openjdk.java.net/~stefank/8170395/webrev.01/
>>> https://bugs.openjdk.java.net/browse/JDK-8170395
>>>
>>> The fix for JDK-8169931 introduced a new assert to ensure that we
>>> always try to allocate chunks that are any of the three fixed sizes
>>> (specialized, small, medium) or a humongous chunk (if it is larger
>>> then the medium chunk size).
>>>
>>> During metaspace initialization an initial metaspace chunk is
>>> allocated. The size of some of the metaspace instances can be
>>> specified on the command line. For example:
>>> java -XX:InitialBootClassLoaderMetaspaceSize=30720 -version
>>>
>>> If this size is smaller than the medium chunk size and at the same
>>> time doesn't match the specialized or small chunk size, then we end up
>>> hitting the assert mentioned above:
>>> #
>>> # Internal Error
>>> (/scratch/opt/jprt/T/P1/142848.erik/s/hotspot/src/share/vm/memory/metaspace.cpp:2359),
>>>
>>> pid=31643, tid=31646
>>> # assert(size > free_chunks(MediumIndex)->size()) failed: Not a
>>> humongous chunk
>>> #
>>>
>>> ========================================================================
>>>
>>> The most important part of the fix is this line:
>>> +  // Adjust to one of the fixed chunk sizes (unless humongous)
>>> +  const size_t adjusted = adjust_initial_chunk_size(requested);
>>>
>>> which ensures that we always request either of a specialized, small,
>>> medium, or humongous chunk size, even if the requested size is neither
>>> of these.
>>>
>>> Most of the other code is refactoring to unify the non-class metaspace
>>> and the class metaspace code paths to get rid of some of the existing
>>> code duplication, bring the chunk size calculation nearer to the the
>>> actual chunk allocation, and make it easier to write a unit test for
>>> the new adjust_initial_chunk_size function.
>>>
>>> ========================================================================
>>>
>>> The patch for JDK-8169931 was backed out with JDK-8170355 and will be
>>> reintroduced as JDK-8170358 when this patch has been reviewed and
>>> pushed.
>>>
>>> Testing: jprt, unit test, parts of PIT testing (including CDS tests),
>>> failing test
>>>
>>> Thanks,
>>> StefanK
>>
>>