From: "tmm1 (Aman Gupta)" <ruby@...1.net>
Date: 2013-10-04T10:53:43+09:00
Subject: [ruby-core:57653] [ruby-trunk - Bug #8983] [PATCH]	GC.stat[:heap_free_num] returns number of unused slots on heap


Issue #8983 has been updated by tmm1 (Aman Gupta).


>  (2) count zombie_num
>  
>  (objspace->heap.limit -
>    (objspace_live_num(objspace) - zombie_num)

I like this approach. This will be useful also for debugging finalizer leaks.

Once we replace heap_free_num with this formula, I would like to rename the existing heap.free_num counter. Do you have any suggestion for a better name? Maybe heap.reused_num or heap.swept_num
----------------------------------------
Bug #8983: [PATCH] GC.stat[:heap_free_num] returns number of unused slots on heap
https://bugs.ruby-lang.org/issues/8983#change-42271

Author: tmm1 (Aman Gupta)
Status: Assigned
Priority: Normal
Assignee: ko1 (Koichi Sasada)
Category: 
Target version: current: 2.1.0
ruby -v: ruby 2.1.0dev (2013-10-03 trunk 43129) [x86_64-darwin12.4.1]
Backport: 1.9.3: UNKNOWN, 2.0.0: UNKNOWN


In ruby 1.9 and 2.0, gc_stat() used to call rest_sweep() so heap_free_num always equals the number of free slots (ObjectSpace.count_objects[:FREE]). In 2.1 the rest_sweep() was removed, so free_num is not always accurate. This patch fixes compatibility with the previous behavior.

With this patch, it is also easier to perform "out-of-band" GC in unicorn and passenger. For example: if your application requires 100k objects per request, then you can run the following in-between every request:

  GC.start if GC.stat[:heap_free_num] < 100_000

I also added a objspace->heap.limit because HEAP_OBJ_LIMIT*heap_used is not accurate due to memory re-alignment in heap_assign_slot.

https://github.com/tmm1/ruby/compare/gc-stat-free-num
https://github.com/tmm1/ruby/compare/gc-stat-free-num.patch


-- 
http://bugs.ruby-lang.org/