From: "peterzhu2118 (Peter Zhu)" Date: 2021-12-13T22:29:01+00:00 Subject: [ruby-core:106647] [Ruby master Feature#18364] Add GC.stat_pool for Variable Width Allocation Issue #18364 has been updated by peterzhu2118 (Peter Zhu). > This seems incompatible and might break existing code which expects GC.stat to return a Hash[Symbol,Integer]. Quoting the dev meeting log: > ko1: Also jruby already extends this method so that it returns more than just a number. > matz: If so I guess we can follow jruby? Personally, I don't have a strong opinion on which route we should take (whether we extend `GC.stat` or add a new method). > Also what should size_t rb_gc_stat(VALUE) return/raise for such a case? I think we should change API for rb_gc_stat to return `VALUE` instead. There probably isn't many users of this API so it shouldn't be a breaking change for many. > Also it's likely to make GC.stat()/GC.stat(hash) slower and use more allocations, which seems suboptimal. > Notably, GC.stat(hash) no longer avoids allocations and becomes useless. We can still achieve this by checking that the non-numeric values of the key are of the correct type and re-using it. Although, this would significantly increase the complexity of the code for `GC.stat`. ---------------------------------------- Feature #18364: Add GC.stat_pool for Variable Width Allocation https://bugs.ruby-lang.org/issues/18364#change-95318 * Author: peterzhu2118 (Peter Zhu) * Status: Open * Priority: Normal * Assignee: matz (Yukihiro Matsumoto) ---------------------------------------- # GitHub PR: https://github.com/ruby/ruby/pull/5177 We're proposing an API to get statistics for size pools for Variable Width Allocation similar to `GC.stat`. This will make it easier for us (and other developers) to tune VWA. Before 3.1 release, we plan to keep this method hidden from the documentation using `:nodoc:` since it is not useful when not using VWA. For example: ```ruby # Get stats for size pool 2 puts GC.stat_pool(2) #=> {:slot_size=>160, :heap_allocatable_pages=>80, :heap_eden_pages=>14, :heap_eden_slots=>1424, :heap_tomb_pages=>0, :heap_tomb_slots=>0} puts GC.stat_pool(2, :heap_eden_pages) #=> 14 ``` We aim to keep the keys in the outputted hash the same as the keys used in `GC.stat`. We chose to implement a new method instead of re-using an existing API (`GC.stat`) because the keys returned by `GC.stat_pool` will not be the same as `GC.stat`. We believe that having `GC.stat` return different shapes of hashes based on its arguments is confusing. -- https://bugs.ruby-lang.org/ Unsubscribe: