Master Thesis on Shenandoah

[Andrew Haley]

On 24/10/17 13:46, Aleksey Shipilev wrote:
> On 10/24/2017 02:43 PM, Andrew Haley wrote:
>> On 18/10/17 21:32, Dominik Inführ wrote:
>>> I was actually hoping that you would tell me this is overkill ;) I will try
>>> to find some and take a heap dump of them.
>>
>> Here's what I got from Eclipse, excluding arrays:
>>
>>     {14571, 491336, 23885, 346712, 745867, 919, 2215, 3782, 3096, 17753, 559, 35539, 127, 27, 474, 10, 144, 9, 11, 10, 8, 5, 1, 17, 515, 1, 16, 0, 0, 0, 0, 0, 17, 1, 0, 0, 0, 0, 0, 2, 0, 34, 37, 23, 10, 42, 26, 47, 26, 8, 7, 6, 15, 5, 5, 0, 28, 36, 25, 7, 10, 11, 4, 0, 1};
>>
>> This is the frequency of objects of various sizes, starting at 0 machine words.
>> This doesn't include the two words at the start of each object.
> 
> That's good, but not enough. We really need to get the shape of the objects (e.g. the number and the
> type of fields) to say if fwdptr compression is able to fit into the alignment gaps within the
> object, thus trimming down the footprint.

Surely it always will, won't it?  Or is this in the case where the
VM manages to get a field in the class gap?

-- 
Andrew Haley
Java Platform Lead Engineer
Red Hat UK Ltd. <https://www.redhat.com>
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