RFR (XS): 8005108: NPG: Add specialized Metachunk sizes for reflection and anonymous classloaders
Stefan Karlsson
stefan.karlsson at oracle.com
Tue Dec 18 16:45:40 UTC 2012
On 18 dec 2012, at 17:30, Jon Masamitsu <jon.masamitsu at oracle.com> wrote:
>
>
> On 12/18/12 04:16, Stefan Karlsson wrote:
>> On 12/18/2012 11:47 AM, Bengt Rutisson wrote:
>>>
>>> Hi Stefan,
>>>
>>> Looks good to me.
>>>
>>> I think this comment in metaspace.cpp can also be removed:
>>>
>>> 2220 // The total words available for metadata allocation. This
>>> 2221 // uses Metaspace capacity_words() which is the total words
>>> 2222 // in chunks allocated for a Metaspace.
>>
>> My change just reverses some of the changes in 3854. This comment was already wrong before that change.
>>
>> Jon, do you think I should remove or reword the comment.
>
> Please remove the comment. The name of the method is
> descriptive enough.
>
> Thanks.
>
> Also, change looks good.
OK.
thanks,
StefanK
>
> Jon
>
>>
>> thanks,
>> StefanK
>>
>>> Bengt
>>>
>>> On 12/18/12 11:02 AM, Stefan Karlsson wrote:
>>>> http://cr.openjdk.java.net/~stefank/8005108/webrev.00/
>>>>
>>>> Description from the bug:
>>>> ---
>>>> The implementation of MetaspaceAux::used_in_bytes(), capacity_in_bytes() and reserved_in_bytes() changed as part of this changeset:
>>>>
>>>> changeset: 3854:90273fc0a981
>>>> user: coleenp
>>>> date: Thu Nov 29 16:50:29 2012 -0500
>>>> summary: 8000662: NPG: nashorn ant clean test262 out-of-memory with Java heap
>>>>
>>>> Before this change it seems like data + classes = total. After this does not seem to hold.
>>>>
>>>> This can be verified by running a simple test that does System.gc() with -XX:+PrintHeapAtGC:
>>>>
>>>> Change 3853:
>>>>
>>>> Metaspace total 3400K, used 2760K, reserved 108544K
>>>> data space 3076K, used 2477K, reserved 6144K
>>>> class space 324K, used 283K, reserved 102400
>>>>
>>>>
>>>> Change 3854:
>>>>
>>>> Metaspace total 3400K, used 3400K, reserved 108544K
>>>> data space 3076K, used 2476K, reserved 6144K
>>>> class space 324K, used 283K, reserved 102400K
>>>>
>>>> In this example capacity and reserved add up, but used does not. I have seen cases where at least capacity also did not add up.
>>>> ---
>>>>
>>>> This patch reverts back to the old implementation. We probably want a better way to count these values, but right now we need consistent numbers.
>>>>
>>>> StefanK
>>>
>>
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