Idea: Implement Concurrent GC on the windows Platform

[Benjamin Thaut]

Hi,

I recently came accross this article:
https://blogs.msdn.microsoft.com/vcblog/2018/09/26/step-back-going-back-in-c-time/
which mentions the following "new" kernel API of Windows.
https://docs.microsoft.com/de-de/windows/desktop/api/processsnapshot/nf-processsnapshot-psscapturesnapshot

It has the following properties (See "under the hood" chapter in 
the first link.)

<quote>
* Create a ‘snapshot’ which looks suspiciously like the child 
process of an existing process that has no threads running.
* Mark the processes memory, it’s page tables (Wikipedia), as 
copy-on-write (Wikipedia). That means that whenever a table is 
written to, the table is copied.
</quote>

Now this looks a lot like a fork. At least it does what you would 
need from a fork for implementing the concurrent GC. If I 
remember correctly the main problem of the concurrent GC on 
windows was that there is no equivalent of fork.

The only problem is that there are no threads running after the 
"fork" but for that CreateRemoteThread could be used.

Unfortunately I currently don't have the time to try this out 
myself. But in case someone has time and is interrested and this 
does work out I could see the concurrent GC become a viable 
replacement option for the current gc.

Main downside is, that this API has been added with Windows 8.1. 
But as windows 7 is going out of support starting in 2020 I think 
this is not that big of a downside.

Kind Regards
Benjamin Thaut