Why does OSThread exist?

[coleen.phillimore at oracle.com]

I've been unhappy with thread.hpp being catch-all for everything with 
nothing factored out.  Thread can still point to things but I'd hate to 
see more stuff go into thread.hpp/cpp.  Please don't go in this direction.

See also: https://bugs.openjdk.java.net/browse/JDK-8264145

thanks,
Coleen

On 12/7/21 8:56 AM, Thomas Stüfe wrote:
> Hi David,
>
> On Tue, Dec 7, 2021 at 10:25 AM David Holmes <david.holmes at oracle.com>
> wrote:
>
>> Hi Thomas,
>>
>> On 7/12/2021 4:30 pm, Thomas Stüfe wrote:
>>> Hi,
>>>
>>> does anybody know what the point is of a separate OSThread companion
>> class
>>> to Thread? I understand that there is OS-specific information one wants
>> to
>>> factor out on a per-platform base, but why two physically separate
>>> structures? AFAICS they never exist separately (an OSThread makes no
>> sense
>>> without a Thread, and vice versa). We pay unnecessarily for two
>>> allocations, C-heap fragmentation, and for one additional dereferencing
>> hop
>>> when accessing OSThread.
>> Can say for sure as it is historical - it's just the way the OS specific
>> part was factored out.
>>
>> We had a project to try and get rid of it a few years ago but it wasn't
>> a clean/simple as thought at the time and the project was dropped. But
>> Solaris complicated things and now that's gone so ...
>>
>>
> Thanks for the explanation. This tickles my cleanup sense and maybe I try
> my hands on it, now Solaris is gone.
>
> Cheers, Thomas
>
>
>
>> Cheers,
>> David
>>
>>> Thanks, Thomas
>>>