[Pharo-project] [Ann] Ephemerons for Cog
"But if the dependents are stored in some global dictionary from model to sequence of dependents then the reference from the global dictionary keeps both the model and the dependents alive." When I hear "global dictionary" I think of a namespace. Perhaps namespaces could add efficiency to the GC. Chris
On 24 May 2011 14:46, Chris Cunnington <smalltalktelevision@gmail.com> wrote:
"But if the dependents are stored in some global dictionary from model to sequence of dependents then the reference from the global dictionary keeps both the model and the dependents alive."
When I hear "global dictionary" I think of a namespace. Perhaps namespaces could add efficiency to the GC.
I don't see how this could improve anything. During full GC, it has to mark all reachable objects, because those which won't be marked will be reclaimed. So, how presence of namespaces could make GC faster?
Chris
-- Best regards, Igor Stasenko AKA sig.
On 05/24/2011 02:57 PM, Igor Stasenko wrote:
On 24 May 2011 14:46, Chris Cunnington<smalltalktelevision@gmail.com> wrote:
"But if the dependents are stored in some global dictionary from model to sequence of dependents then the reference from the global dictionary keeps both the model and the dependents alive."
When I hear "global dictionary" I think of a namespace. Perhaps namespaces could add efficiency to the GC.
I don't see how this could improve anything. During full GC, it has to mark all reachable objects, because those which won't be marked will be reclaimed.
So, how presence of namespaces could make GC faster? If you know up-front that the namespace doesn't disappear, you could separate those objects from the rest of the objects (in a separate heap) and avoid marking/sweeping altogether. Basically a multi-heap generational GC; with namespaces rather than just generations based on age. Pointers going from one heap to another would have to go over a handle table, as is usual...
Good point Toon. This is what HotSpot does actually. Alexandre On 24 May 2011, at 09:20, Toon Verwaest wrote:
On 05/24/2011 02:57 PM, Igor Stasenko wrote:
On 24 May 2011 14:46, Chris Cunnington<smalltalktelevision@gmail.com> wrote:
"But if the dependents are stored in some global dictionary from model to sequence of dependents then the reference from the global dictionary keeps both the model and the dependents alive."
When I hear "global dictionary" I think of a namespace. Perhaps namespaces could add efficiency to the GC.
I don't see how this could improve anything. During full GC, it has to mark all reachable objects, because those which won't be marked will be reclaimed.
So, how presence of namespaces could make GC faster? If you know up-front that the namespace doesn't disappear, you could separate those objects from the rest of the objects (in a separate heap) and avoid marking/sweeping altogether. Basically a multi-heap generational GC; with namespaces rather than just generations based on age. Pointers going from one heap to another would have to go over a handle table, as is usual...
-- _,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;: Alexandre Bergel http://www.bergel.eu ^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;.
On 24 May 2011 15:20, Toon Verwaest <toon.verwaest@gmail.com> wrote:
On 05/24/2011 02:57 PM, Igor Stasenko wrote:
On 24 May 2011 14:46, Chris Cunnington<smalltalktelevision@gmail.com> Â wrote:
"But if the dependents are stored in some global dictionary from model to sequence of dependents then the reference from the global dictionary keeps both the model and the dependents alive."
When I hear "global dictionary" I think of a namespace. Perhaps namespaces could add efficiency to the GC.
I don't see how this could improve anything. During full GC, it has to mark all reachable objects, because those which won't be marked will be reclaimed.
So, how presence of namespaces could make GC faster?
If you know up-front that the namespace doesn't disappear, you could separate those objects from the rest of the objects (in a separate heap) and avoid marking/sweeping altogether. Basically a multi-heap generational GC; with namespaces rather than just generations based on age. Pointers going from one heap to another would have to go over a handle table, as is usual...
Yes. Object spaces with gates between them. But this is orthogonal to Ephemerons. -- Best regards, Igor Stasenko AKA sig.
In VisualWorks, the place where objects that are likely never garbage live is called perm space. You get a GC speedup roughly proportional to the fraction of the image that is perm space (because you don't have to scan it or mark it), as long as the GC is not global (i.e.: when you also want to get rid of perm space garbage). On 5/24/11 7:29 , Igor Stasenko wrote:
On 24 May 2011 15:20, Toon Verwaest<toon.verwaest@gmail.com> wrote:
On 05/24/2011 02:57 PM, Igor Stasenko wrote:
On 24 May 2011 14:46, Chris Cunnington<smalltalktelevision@gmail.com> wrote:
"But if the dependents are stored in some global dictionary from model to sequence of dependents then the reference from the global dictionary keeps both the model and the dependents alive."
When I hear "global dictionary" I think of a namespace. Perhaps namespaces could add efficiency to the GC.
I don't see how this could improve anything. During full GC, it has to mark all reachable objects, because those which won't be marked will be reclaimed.
So, how presence of namespaces could make GC faster?
If you know up-front that the namespace doesn't disappear, you could separate those objects from the rest of the objects (in a separate heap) and avoid marking/sweeping altogether. Basically a multi-heap generational GC; with namespaces rather than just generations based on age. Pointers going from one heap to another would have to go over a handle table, as is usual...
Yes. Object spaces with gates between them.
But this is orthogonal to Ephemerons.
participants (5)
-
Alexandre Bergel -
Andres Valloud -
Chris Cunnington -
Igor Stasenko -
Toon Verwaest