Ruby Issue Tracking System

01/26/2026

06:01 PM Ruby Feature #21846 (Closed): Add a fast path for GC sweeping

Applied in changeset commit:git|c21f3490d1f28b43564639ae8563bc2e02e828a4.
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Implement a fast path for sweeping (gc_sweep_fast_path_p).
[Feature #21846]
There is a single path through our GC Sweeping code, and we always call
r... eightbitraptor (Matt V-H)

06:01 PM Ruby Revision c21f3490 (git): Implement a fast path for sweeping (gc_sweep_fast_path_p).

[Feature #21846]
There is a single path through our GC Sweeping code, and we always call
rb_gc_obj_free_vm_weak_references and rb_gc_obj_free before adding the
object back to the freelist.
We do this even when the object has no externa... eightbitraptor (Matt V-H)

06:01 PM Ruby Revision 211714f1 (git): Clarify the use of some FLAGS

eightbitraptor (Matt V-H)

06:01 PM Ruby Revision efde37b7 (git): Move the gc fast path out of the default GC impl

It relies too much on VM level concerns, such that it can't be built
with modular GC enabled.
We'll move it into the VM, and then expose it to the GC
implementations so they can use it. eightbitraptor (Matt V-H)

06:01 PM Ruby Revision 8e73aa7f (git): We don't need this wrapper function anymore

eightbitraptor (Matt V-H)

06:01 PM Ruby Revision 7444f415 (git): rename rb_gc_obj_free_on_sweep -> rb_gc_obj_needs_cleanup_p

eightbitraptor (Matt V-H)

06:01 PM Ruby Revision d15117e2 (git): BIGNUM can't have fields other than object_id

eightbitraptor (Matt V-H)

06:01 PM Ruby Revision 3c634893 (git): Remove the unnecesary integer comparison

Most compilers will optimise this anyway eightbitraptor (Matt V-H)

01/23/2026

07:40 PM Ruby Feature #21846: Add a fast path for GC sweeping

My original implementation of this idea had an extra bitmap used to determine whether each object needed a "full sweep" or not. I abandoned this idea partly because having to remember to manually update the flag and keep it in sync when ... eightbitraptor (Matt V-H)

01/20/2026

11:29 AM Ruby Feature #21846 (Closed): Add a fast path for GC sweeping

[Github PR 15885](https://github.com/ruby/ruby/pull/15885)
## Summary
This proposal adds a fast path through the garbage collector's sweep phase that skips expensive cleanup operations for objects that don't require them. Simple em... eightbitraptor (Matt V-H)