• Per =?UTF-8?B?Tm9yZGzDtnc=?= (10/10) Oct 13 2018 If a D-program GC-allocates via `new` an array spanning multiple
• Sjoerd Nijboer (4/14) Oct 13 2018 I don't believe the GC frees half of allocated memory if there
• Kagamin (3/7) Oct 13 2018 IIRC GC never frees anything

Per =?UTF-8?B?Tm9yZGzDtnc=?= <per.nordlow gmail.com> writes:

If a D-program GC-allocates via `new` an array spanning multiple 
pages but after processing only keeps a slice to it that fits 
inside a single `mmape`d page will GC-collection then free the 
other unreferenced pages?

I realize that such a feature in a GC of any language and type 
must rely on the OS memory manager being able to free parts of a 
previously allocated set of continuously positioned pages.

Does this depend on whether the used page is the first, last or a 
page in the middle of the set of pages allocated in one call to 
mmap.

Sjoerd Nijboer <dlang sjoerdnijboer.com> writes:

On Saturday, 13 October 2018 at 18:40:58 UTC, Per Nordlöw wrote:
 If a D-program GC-allocates via `new` an array spanning 
 multiple pages but after processing only keeps a slice to it 
 that fits inside a single `mmape`d page will GC-collection then 
 free the other unreferenced pages?

 I realize that such a feature in a GC of any language and type 
 must rely on the OS memory manager being able to free parts of 
 a previously allocated set of continuously positioned pages.

 Does this depend on whether the used page is the first, last or 
 a page in the middle of the set of pages allocated in one call 
 to mmap.

I don't believe the GC frees half of allocated memory if there 
are no references to the unreferenced point.
It would break c style strings I think.

Kagamin <spam here.lot> writes:

On Saturday, 13 October 2018 at 18:40:58 UTC, Per Nordlöw wrote:
 If a D-program GC-allocates via `new` an array spanning 
 multiple pages but after processing only keeps a slice to it 
 that fits inside a single `mmape`d page will GC-collection then 
 free the other unreferenced pages?

IIRC GC never frees anything 
https://issues.dlang.org/show_bug.cgi?id=3284 was it fixed?