Header size with -XX:-UseCompressedOops

[Stefan Reich]

Hi Thomas,

oh! Never heard about that change. Now I know. And yes this changes the
picture as expected.

Thanks

On Mon, 11 Apr 2022 at 19:28, Thomas Stüfe <thomas.stuefe at gmail.com> wrote:

> Hi Stefan,
>
> I think you want to set CompressedClassPointers.
>
> There used to be a dependency between CompressedOops and
> CompressedClassPointers - switching the former off switched the latter off
> too - but that dependency is gone and these settings are now independent of
> each other.
>
> Cheers, Thomas
>
> On Mon, Apr 11, 2022 at 6:57 PM Stefan Reich <
> stefan.reich.maker.of.eye at googlemail.com> wrote:
>
>> Hi, quick question to the experts.
>>
>> Java object header size is 12 bytes with CompressedOOPS (have verified
>> this
>> many times).
>>
>> Now I did a test with -XX:-UseCompressedOops just for fun and found that
>> headers are still 12 bytes?
>>
>> I verified this in two ways:
>>
>> a. using Unsafe.objectFieldOffset
>> b. making a whole lot of identical objects and measuring heap use before
>> and after (with calls to System.gc)
>>
>> Both these methods give me a size of 16 bytes for an object with a single
>> int field.
>>
>> How is this possible?
>>
>> Many greetings
>> Stefan Reich
>>
>> --
>> == Gaz.AI ==
>>
>

-- 
== Gaz.AI ==