Bug 8500 – DList extremely wasteful in node allocation

Status
NEW
Severity
enhancement
Priority
P4
Component
phobos
Product
D
Version
D2
Platform
All
OS
All
Creation time
2012-08-02T14:18:38Z
Last change time
2024-12-01T16:15:27Z
Assigned to
No Owner
Creator
Alex Rønne Petersen
Moved to GitHub: phobos#9933 →

Comments

Comment #0 by alex — 2012-08-02T14:18:38Z
The DList container currently allocates a Node struct with the GC instead of managing their memory manually. I don't know if there's anything preventing manual memory management here, but the current approach is extremely wasteful.
Comment #1 by issues.dlang — 2012-08-02T15:38:29Z
I wouldn't expect it to do anything else until custom allocators are implemented. Then the allocator used will determine the allocation scheme used.
Comment #2 by andrei — 2012-08-02T15:45:27Z
This is following the traditional approach of Java and other languages. Allocators will take care of this.
Comment #3 by alex — 2012-08-02T17:57:31Z
> I wouldn't expect it to do anything else until custom allocators are implemented. Then the allocator used will determine the allocation scheme used. I'd honestly expected it to use malloc/free like Array(T). > This is following the traditional approach of Java and other languages. Allocators will take care of this. Right, I'm just saying that the inefficiency of insertions (which is one of the most common operations next to removal) in DList almost negates any performance gained by using it instead of a plain Array(T) for some use cases (for me, instruction streams in a JIT compiler). For large workloads, it'll induce a lot of GC cycles, scanning, and freeing, which is way worse for throughput than the slightly less efficient insertion and removal algorithms on an Array(T) which at least use malloc/free. I know allocators will solve this, but I think that a malloc/free approach in the meantime would be reasonable enough (if doable).
Comment #4 by robert.schadek — 2024-12-01T16:15:27Z
THIS ISSUE HAS BEEN MOVED TO GITHUB https://github.com/dlang/phobos/issues/9933 DO NOT COMMENT HERE ANYMORE, NOBODY WILL SEE IT, THIS ISSUE HAS BEEN MOVED TO GITHUB