# Longlife gc

**URL:** <https://www.ruby-forum.com/t/longlife-gc/167634>\
**Category:** Development\
**Created:** [May 10, 2009, 5:21pm UTC](https://www.ruby-forum.com/t/longlife-gc/167634 "2009-05-10T17:21:25Z")\
**Posts on this page:** 9\
**Page:** 1

<div class="post-metadata">

**Author:** ![Narihiro\_N](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/9fc29f/32.png) [@Narihiro\_N](https://www.ruby-forum.com/u/Narihiro_N)\
**Post date:** [May 10, 2009, 5:21pm UTC](https://www.ruby-forum.com/t/longlife-gc/167634/1 "2009-05-10T17:21:25Z")

</div>

nariと申します．

GW中にGCã®æ”¹è‰¯ã‚’è¡Œã„ã¾ã—ãŸã®ã§ï¼Œå ±å‘Šã„ãŸã—ã¾ã™ï¼Ž

= Railsのヒープ調査  
2ヶ月ほど前に，ふと気になってRailsがどんな風にヒープを使用しているか調査してみました．  
以下のグラフはscaffoldしたRailsアプリを動かした際のものです．  
[![](http://www.narihiro.info/resource/image/gc_count_statistic_from_rails.png) ](http://www.narihiro.info/resource/image/gc_count_statistic_from_rails.png)

èª¿æŸ»å‰ã¯æ¼ ç„¶ã¨ã€Œæ–‡å­—åˆ—ãŒä¸€ç•ªå¤šã„ã‚“ã˜ã‚ƒãªã„ã‹ãªãã€ã¨è€ƒãˆã¦ã„ãŸã®ã§ã™ãŒï¼Œå®Ÿéš›ã«  
ã¯æ§‹æ–‡æœ¨ã‚ªãƒ–ã‚¸ã‚§ã‚¯ãƒˆãŒãƒ’ãƒ¼ãƒ—ã®åŠåˆ†ã‚’å ã‚ã¦ã„ã‚‹ã‚ˆã†ã§ã™ï¼Ž  
その構文木オブジェクトを更に詳しく調べたグラフが以下です．  
[![](http://www.narihiro.info/resource/image/gc_count_statistic_for_node_from_rails.png) ](http://www.narihiro.info/resource/image/gc_count_statistic_for_node_from_rails.png)

このグラフにあるNODE\_METHODやNODE\_CFUNC，NODE\_FBODYはメソッド定義の際に  
使用され，NODE\_WHILEやNODE\_BLOCKはVMの内部で使用されているようです．

= 長寿命GC  
更に調査をすると，これらのオブジェクトはとても長生きな事が分かりました．  
ãã“ã§ï¼Œã“ã‚Œã‚‰ã‚’é•·å¯¿å‘½é ˜åŸŸã«éš”é›¢ã—ã¦ã—ã¾ãŠã†ï¼Œã¨ã„ã†æ”¹å–„ã‚’ä»Šå›žè¡Œã„ã¾ã—ãŸï¼Ž  
部分的な世代別GCというイメージです．  
このアイデアは，まつもとさんからアドバイスしていただいたものです．

= 実装メモ  
major gcを行うタイミングはヒープが拡張される時とGC.startの時にしています．  
ライトバリアの手法にはremembered\_setを使いました．オブジェクトがライト  
バリアにあることを示す為に FL\_RESERVED フラグを使用しています．

= ベンチマーク  
scaffoldしただけのRailsアプリでGCのプロファイルを取りました．  
GC回数  
改善前 : 35  
改善後 : 31

総GC時間(ms)  
改善前 : 332.02  
改善後 : 284.01

平均GC時間(ms)  
改善前 : 9.48  
改善後 : 9.16

また，Railsアプリのヒープの状態を作り出すようなベンチマークコードを書い  
て，そのプロファイルも取りました．  
GC回数  
改善前 : 7  
改善後 : 6

総GC時間(ms)  
改善前 : 1452.09  
改善後 : 1208.07

平均GC時間(ms)  
改善前 : 207.44  
改善後 : 201.34

使用したコードは本メールに添付しております．

= パッチ  
現在の最新のrevisionへのパッチとruby1.9.1-p0へのパッチを作成しました．  
本メールに添付しております．

よろしくお願いいたします．

---

<div class="post-metadata">

**Author:** ![Narihiro\_N](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/9fc29f/32.png) [@Narihiro\_N](https://www.ruby-forum.com/u/Narihiro_N)\
**Post date:** [May 10, 2009, 5:43pm UTC](https://www.ruby-forum.com/t/longlife-gc/167634/2 "2009-05-10T17:43:45Z")

</div>

e$B$^$D$b$He(B e$B$f$-$R$m!we(BEurukoe$B:G=\*F|$G$9e(B

In message “Re: [ruby-dev:38423] longlife gc”  
on Mon, 11 May 2009 00:20:38 +0900, Narihiro N.  
[removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) writes:

|GWe$BCf$Ke(BGCe$B$N2~NI$r9T$$$^$7$?$N$G!$Js9p$$$?$7$^$9!%e(B

e$B;d$,@z$C$?$3$H$b$“$j$^$9$,!“0-$/$J$k%1!\<%9$,$J$$e(B or e$B\>/$J$$$Ne(B  
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e$B;n$7$F$_$h$&$H;W$$$^$9$,!”$$$D;~4V$,\<h$l$k$+J,$+$i$J$$$N$G!#e(B

---

<div class="post-metadata">

**Author:** ![Narihiro\_N](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/9fc29f/32.png) [@Narihiro\_N](https://www.ruby-forum.com/u/Narihiro_N)\
**Post date:** [May 10, 2009, 8:54pm UTC](https://www.ruby-forum.com/t/longlife-gc/167634/3 "2009-05-10T20:54:17Z")

</div>

e$B!!$5$5$@$G$9!%e(B

Narihiro N. wrote::

> e$B$3$N%0%i%U$K$"$ke(BNODE\_METHODe$B$de(BNODE\_CFUNCe$B!$e(BNODE\_FBODYe$B$O%a%=%C%IDj5A$N:]$Ke(B  
> e$B;HMQ$5$l!$e(BNODE\_WHILEe$B$de(BNODE\_BLOCKe$B$Oe(BVMe$B$NFbIt$G;HMQ$5$l$F$$$k$h$&$G$9!%e(B

e$B!!$\*Hh$lMM$G$9!%$9$P$i$7$$%G!\<%?$@$H;W$$$^$9!%e(B

> = e$BD9\<wL?e(BGC  
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e$B$H;W$$$^$9!%e(B

---

<div class="post-metadata">

**Author:** ![Narihiro\_N](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/9fc29f/32.png) [@Narihiro\_N](https://www.ruby-forum.com/u/Narihiro_N)\
**Post date:** [May 11, 2009, 3:11pm UTC](https://www.ruby-forum.com/t/longlife-gc/167634/4 "2009-05-11T15:11:34Z")

</div>

narie$B$G$9!%e(B

2009/05/11 3:52 SASADA Koichi [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid):

> e$B!!$5$5$@$G$9!%e(B

(snip)

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e$B$7$?$N$G$9$,!$5U$K$o$+$j$E$i$+$C$?$+$b$7$l$^$;$s!%e(B

---

<div class="post-metadata">

**Author:** ![Narihiro\_N](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/9fc29f/32.png) [@Narihiro\_N](https://www.ruby-forum.com/u/Narihiro_N)\
**Post date:** [May 11, 2009, 3:05pm UTC](https://www.ruby-forum.com/t/longlife-gc/167634/5 "2009-05-11T15:05:40Z")

</div>

narie$B$G$9!%e(B

2009/05/11 0:39 Yukihiro M. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid):

> e$B;n$7$F$\_$h$&$H;W$$$^$9$,!"$$$D;~4V$,\<h$l$k$+J,$+$i$J$$$N$G!#e(B

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e$B$h$m$7$/$\*4j$$$$$?$7$^$9!%e(B

---

<div class="post-metadata">

**Author:** ![Narihiro\_N](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/9fc29f/32.png) [@Narihiro\_N](https://www.ruby-forum.com/u/Narihiro_N)\
**Post date:** [May 13, 2009, 8:22am UTC](https://www.ruby-forum.com/t/longlife-gc/167634/6 "2009-05-13T08:22:23Z")

</div>

e$B$^$D$b$He(B e$B$f$-$R$m$G$9e(B

In message “Re: [ruby-dev:38424] Re: longlife gc”  
on Mon, 11 May 2009 00:39:12 +0900, Yukihiro M.  
[removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) writes:

|In message “Re: [ruby-dev:38423] longlife gc”  
| on Mon, 11 May 2009 00:20:38 +0900, Narihiro N. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) writes:  
|  
||GWe$BCf$Ke(BGCe$B$N2~NI$r9T$$$^$7$?$N$G!$Js9p$$$?$7$^$9!%e(B  
|  
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benchmarke$B0J2\<$N%9%/%j%W%H$G;n$7$F$\_$^$7$?!#$H$j$“$($:7kO@$H$7e(B  
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---

<div class="post-metadata">

**Author:** ![Narihiro\_N](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/9fc29f/32.png) [@Narihiro\_N](https://www.ruby-forum.com/u/Narihiro_N)\
**Post date:** [May 13, 2009, 4:08pm UTC](https://www.ruby-forum.com/t/longlife-gc/167634/7 "2009-05-13T16:08:41Z")

</div>

narie$B$G$9!%e(B

2009/05/13 15:21 Yukihiro M. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid):

> |e$B;d$,@z$C$?$3$H$b$“$j$^$9$,!“0-$/$J$k%1!\<%9$,$J$$e(B or e$B\>/$J$$$Ne(B  
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> 
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e$B$"$j$,$H$&$4$6$$$^$9!%e(B  
e$B%3%\_%C%H$7$F$\*$-$^$9!%e(B

---

<div class="post-metadata">

**Author:** ![Narihiro\_N](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/9fc29f/32.png) [@Narihiro\_N](https://www.ruby-forum.com/u/Narihiro_N)\
**Post date:** [May 13, 2009, 11:06pm UTC](https://www.ruby-forum.com/t/longlife-gc/167634/8 "2009-05-13T23:06:06Z")

</div>

In article  
[removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid),  
Narihiro N. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) writes:

> e$B%3%\_%C%H$7$F$\*$-$^$9!%e(B

test-all e$B$G0[\>o=\*N;$9$k$h$&$G$9$M!#e(B

Segmentation fault:  
[http://www.rubyist.net/~akr/chkbuild/debian/ruby-trunk/log/20090514T030700.log.txt.gz](http://www.rubyist.net/~akr/chkbuild/debian/ruby-trunk/log/20090514T030700.log.txt.gz)

Bus Error:  
[http://chkbuild.n-z.jp/ruby/ppc-mac-mini/ruby-trunk/log/20090514T034826.log.txt.gz](http://chkbuild.n-z.jp/ruby/ppc-mac-mini/ruby-trunk/log/20090514T034826.log.txt.gz)

---

<div class="post-metadata">

**Author:** ![Narihiro\_N](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/9fc29f/32.png) [@Narihiro\_N](https://www.ruby-forum.com/u/Narihiro_N)\
**Post date:** [May 14, 2009, 3:57am UTC](https://www.ruby-forum.com/t/longlife-gc/167634/9 "2009-05-14T03:57:29Z")

</div>

narie$B$G$9!%e(B

2009/05/14 6:05 Tanaka A. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid):

> Bus Error:  
> [http://chkbuild.n-z.jp/ruby/ppc-mac-mini/ruby-trunk/log/20090514T034826.log.txt.gz](http://chkbuild.n-z.jp/ruby/ppc-mac-mini/ruby-trunk/log/20090514T034826.log.txt.gz)

e$B$&$%!$$9$\_$^$;$s!%e(B  
e$BD4::$7$^$9!%e(B