Suggested fix for JDK-4724038 (Add unmap method to MappedByteBuffer)
Alan.Bateman at oracle.com
Wed Sep 9 12:44:53 UTC 2015
On 09/09/2015 13:41, David M. Lloyd wrote:
> If you have access to a Windows development environment, it seems to
> me that you could help directly with the testing required to determine
> a solution.
> I think my proposed remapping approach will work, but it is contingent
> on testing the following on Windows:
> * Determine if it is possible to remap the pages previously mapped to
> a file view without first unmapping them. Preferably, the pages would
> be remapped as inaccessible (equivalent to POSIX PROT_NONE).
> * Determine if such remapping releases the file to be deleted, or, if
> not, determine if the previously mapped file view can be unmapped
> without affecting the remapped pages.
> If the answer to both of these can be shown to be affirmative, then I
> think there is a real viable solution which allows immediate release
> of backing resources, with the address space being reclaimed by GC.
There are a few contributions from Microsoft on this mailing list and
they might be able to jump in on this discussion. When we last explored
the remapping approach (about 5 years ago) then we didn't find a way to
do it atomically so we gave up. It's good to explore this again with
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