From: Eric Wong <normalperson@...>
Date: 2014-12-26T21:49:10+00:00
Subject: [ruby-core:67155] Re: [ruby-trunk - Feature #10658] [Open] ThreadGroup local variables

godfat@godfat.org wrote:
> * What I was doing before: Assume ThreadGroup#list.first is the owner of
>   the group, thus the worker thread, and use that thread to store the number.
>   Something like:
> 
>       Thread.current.group.list.first[:assertions] += 1
> 
>   This works for Ruby 1.9, 2.0, 2.1, but not for 2.2.
>   This also works for Rubinius. I thought this is somehow an expected behaviour,
>   therefore did a patch for JRuby to make this work:
>   https://github.com/jruby/jruby/pull/2221
>   Until now it failed on Ruby 2.2, did I know the order was not preserved...

Oops, can you try the following?

--- a/vm_core.h
+++ b/vm_core.h
@@ -975,7 +975,7 @@ rb_vm_living_threads_init(rb_vm_t *vm)
 static inline void
 rb_vm_living_threads_insert(rb_vm_t *vm, rb_thread_t *th)
 {
-    list_add(&vm->living_threads, &th->vmlt_node);
+    list_add_tail(&vm->living_threads, &th->vmlt_node);
     vm->living_thread_num++;
 }
 
Ordering is preserved, just backwards.
But I am unsure if order should be spec which is relied on...