Issue #16124 has been updated by ko1 (Koichi Sasada). Status changed from Assigned to Rejected transient heap was removed. ---------------------------------------- Misc #16124: Let the transient heap belong to objspace https://bugs.ruby-lang.org/issues/16124#change-110882 * Author: methodmissing (Lourens Naudé) * Status: Rejected * Assignee: ko1 (Koichi Sasada) ---------------------------------------- As per comment from Nobu in https://github.com/ruby/ruby/pull/2303#issuecomment-523248875 , I took an initial stab @ a tighter integration between objspace and the transient heap in https://github.com/ruby/ruby/pull/2400 ### Benefits * Multi-VM (MVM) friendly - ( vm -> objspace -> theap ) * The 32MB (current size) arena lazy allocated on ruby init is now properly freed on shutdown as well * It feels strange that the evacuation from the current global theap is to objspace, whereas the space evacuated from is a global arena. ### Not so great * A fast reference to a global variable `global_transient_heap` becomes a function call to `rb_objspace_get_theap()` and related pointer chasing from vm -> objspace -> theap * Some internal transient heap structs moved to the header file now leaks into all other reference sites where this source file (`transient_heap.c`) as previously just used for API * I'm not sure exactly of the boundary Koichi had in mind for the GC compile module and how tightly it should (or shouldn't) be coupled to the transient heap. `struct rb_objspace*` declarations elsewhere for example reveals nothing about the structure members for example, whereas with this PR a lot of transient heap internals are exposed via the header file now * Also possible to move `transient_heap.c` into `gc.c` - I feel theap is not an experimental feature anymore and has been stable for quite some time with plausible performance benefits. The downside of that is `gc.c` is quite dense already, but then all ruby heap management concerns belong to one compile unit. In a similar vein the global method cache could perhaps belong to the VM instance as well, effectively better alignment with MVM and also easier to have a balanced VM setup and teardown sequence without anything left dangling on ruby shutdown. Thoughts? -- https://bugs.ruby-lang.org/