RFR: 8058963: CollectorPolicy::satisfy_failed_metadata_allocation can avoid some safepoints

[Erik Helin]

On 2014-09-29 10:14, Bengt Rutisson wrote:
>
> On 2014-09-26 16:45, Erik Helin wrote:
>> Hi Bengt,
>>
>> On 2014-09-26 12:49, Bengt Rutisson wrote:
>>>
>>> Hi Erik,
>>>
>>> The change looks good.
>>
>> thanks!
>>
>> On 2014-09-26 12:49, Bengt Rutisson wrote:
>>> One minor thing is that Metaspace::expand_and_allocate() and
>>> Metaspace::allocate() have different exposure even though they are both
>>> supposed to be internal to Metaspace. It would be nice to treat them the
>>> same way. Talked to Erik and we think that keeping the friend
>>> declaration of CollectorPolicy makes sense and in that case we can move
>>> expand_and_allocate() from being public to being private.
>>
>> Good idea, I've uploaded new webrevs:
>> - full: http://cr.openjdk.java.net/~ehelin/8058963/webrev.01/
>> - inc: http://cr.openjdk.java.net/~ehelin/8058963/webrev.00-01/
>
> Looks good.

Thanks!
Erik

> Bengt
>
>
>
>>
>> Thanks,
>> Erik
>>
>>> Thanks,
>>> Bengt
>>>
>>>
>>> On 2014-09-23 17:15, Erik Helin wrote:
>>>> Hi all,
>>>>
>>>> this small change enables us to skip two possible safepoints in
>>>> CollectorPolicy::satisfy_failed_metadata_allocation:
>>>>
>>>> 1. When a thread continues a loop after having been stalled due to a
>>>> GC_locker initiated Full GC.
>>>> 2. When the VM_CollectForMetadata VM operation's prologue fails
>>>> because a full GC has already been run just prior to the
>>>> CollectForMetadata VM operation.
>>>>
>>>> The way this is done is simply by trying to allocate at the start of
>>>> the loop. This way, whenever we loop around and a full GC has
>>>> happened, the allocation request might be satisfied and we can do an
>>>> early return.
>>>>
>>>> Webrev:
>>>> http://cr.openjdk.java.net/~ehelin/8058963/webrev.00/
>>>>
>>>> Bug:
>>>> https://bugs.openjdk.java.net/browse/JDK-8058963
>>>>
>>>> Testing:
>>>> - JPRT
>>>> - Aurora:
>>>>   - Kitchensink
>>>>   - Weblogic+Medrec
>>>>   - runThese
>>>>   - vm.quick, regression, gc, compiler, runtime, parallel class
>>>> loading,
>>>>     metaspace, oom
>>>>   - JTReg tests
>>>>
>>>> Thanks,
>>>> Erik
>>>
>