[ruby-core:38193] [Ruby 1.9 - Feature #5033] PATCH: 1.9: gc_mark_children: Avoid gc_mark() tail recursion, use goto again.

Issue #5033 has been updated by Kurt  Stephens.


I don't know of a reliable means to record max stack depth, but the speed isn't necessarily better or worse:

 > bash ./profile-gc-mark 
+ export 'CFLAGS=-O2 -I/opt/local/include' LDFLAGS=-L/opt/local/lib
+ CFLAGS='-O2 -I/opt/local/include'
+ LDFLAGS=-L/opt/local/lib
+ for branch in trunk trunk-gc-mark-optimization
+ git checkout trunk
Switched to branch 'trunk'
Your branch is ahead of 'origin/trunk' by 10 commits.
+ prefix=/Users/stephens/local/ruby-trunk
+ make test
+ make test

real	0m51.808s
user	0m19.760s
sys	0m13.118s
+ make test

real	0m49.938s
user	0m19.598s
sys	0m13.396s
+ for branch in trunk trunk-gc-mark-optimization
+ git checkout trunk-gc-mark-optimization
Switched to branch 'trunk-gc-mark-optimization'
+ prefix=/Users/stephens/local/ruby-trunk-gc-mark-optimization
+ make test
+ make test

real	0m51.752s
user	0m19.526s
sys	0m13.336s
+ make test

real	0m50.157s
user	0m19.735s
sys	0m13.487s

BTW: make test-all in trunk hangs for me on OS X 64.

The space improvements would occur for NODES with deep obj->as.node.u3.node, arrays with deep last elements, and OBJECTS where the last IVAR is deep.

obj->as.file.fptr->write_lock, obj->as.regexp.src, obj->as.match.str, obj->as.rational.den, obj->as.complex.imag are likely to be not deep.

So maybe this patch is pointless, except for the removal of the unnecessary "long i" variable in the T_OBJECT case/loop.





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Feature #5033: PATCH: 1.9: gc_mark_children: Avoid gc_mark() tail recursion, use goto again.
http://redmine.ruby-lang.org/issues/5033

Author: Kurt  Stephens
Status: Assigned
Priority: Normal
Assignee: Narihiro Nakamura
Category: core
Target version: 1.9.x


Minor GC improvement.

Avoid recurring into gc_mark() when "goto again;" is sufficient.

-- KAS



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