????????е?Java?б?????????????????

???????????? ???????[ 2012/5/2 11:14:55 ] ????????

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??????Щ??????????????????в????LinkedList???????????????????????????????????????????н????????????????????????????????????????????????????????????????LinkedList??ArrayList?????????????????????

??????????????????????????С?????????λ?t?????????????λ??????????????м??????????????????????????л??????????????????????????λ?????????????β???м???????????????С???е??100?????????????10??000???????????????1??000??000????????

??????????????У?????????JAVA SDK 1.2.0??1.3.0??е?SUN JVM???????????HOTSPOT JVM 2.0??????????????汾??????1.3.0 SDK???????????????У??????????????????????????SDK 1.2 VM?????????????????????????????????????????????????JVM?????????????JIT??????????????JVM?????????????????????????????????????м??????????β????????????????????????????????β??????????????????????????????μ????????????????飩??????????????????????????????г?????κβ??????????????????????????????????????????????????????????????????????????????У??????????????????????? ??1??????????е??С??????100?????????????е????????????????С??????

??

??1??????????е??С??????100?????????????е????????????????С??????
??	1.2 JVM	1.3 JVM	HotSpot 2.0 JVM
???????ArrayList????	(48.0%)	184.9% (152.0%)	108.0% (66.7%)
???????LinkedList????	135.5%	109.1%	85.3%
???????ArrayList???м?	130.0% (40.6%)	187.4% (158.0%)	84.7% (46.0%)
???????LinkedList???м?	174.0%	135.0%	102.3%
???????ArrayList???β	63.3% (20.7%)	65.9% (25.0%)	60.3% (29.3%)
???????LinkedList???β	106.7%	86.3%	80.3%

????????С??????ArrayList??LinkedList?????????????????????????β??????????????ArrayList???????????????????????????ArrayList?????????????????????????????????????С?????????Java???饗????Object[]?????κμ?????????и??????????????????????????????????????????????????????JVM???????????????????????????

???????磬??????????????????λ?????????1??????У???HotSpot 2.0 JVM??LinkedList???к???????85.3%??????????λ???? 1.2 JVM??ArrayList??????????????????????1.2?м???JIT??????????е???????????????????????к???Ч?????HotSpot?и????JVM?????????????????????????????????????????????????LinkedList??????????????????????code-inlining?????????1.3 JVM??????????????????????????????????????????????????????????JVM?汾?е???????

?????????????????в??????ArrayList?????LinkedList???????????????????????С????????????????????ArrayList?????????????????????С?????磬???????ArrayList???????????100???????????????????????????????????????????????????????1?????е?????????????????????С????????????LinkedList????? SDK 1.3??????????????С??

????????ArrayList??????????????????????????????????????????????????????????????ArrayList??????????????????????????????????????LinkedList????????????κ?????????????????????????????????????????LinkedList?????????????????????????????????Щ??????????κ???С??????????????????ArrayList??????LinkedList?? ??2?????????????????10??000??????

??2?????????????????10??000??????
??	1.2 JVM	1.3 JVM	HotSpot 2.0 JVM
???????ArrayList????	7773%	7537%	7500%
???????LinkedList????		90.34%	65.6%
???????ArrayList???м?	3318%	3412%	3121%
???????LinkedList???м?	26264%	14315%	14209%
???????ArrayList???β	41.4%	41.2%	37.5%
???????LinkedList???β	66.4%	73.9%	61.7%

??2????????????????????????????????????????????????????????????????????????????????????????????????????????????LinkedList?????????γ?????????????????м???????????????????????????ArrayList?????????????????????????????LinkedList??????????????м??????????Щ???????????????????????????????ArrayList?м??????????????

????????????ArrayList????????????????±?????????????????????????????????????λ??????Ρ????????????????????????п????λ???LinkedList???и??????????????????????????????????ArrayList??????????????????????????????????????[size -index]??????????????е?λ?á? ??3????????????????1??000??000??????

??3????????????????1??000??000??????
??	1.2 JVM	1.3 JVM	HotSpot 2.0 JVM
???????ArrayList????	???	???	???
???????LinkedList????		179.5%	144.1%
???????ArrayList???м?	???	???	???
???????LinkedList???м?	???	???	???
???????ArrayList???β	38.3%	47.7%	42.9%
???????LinkedList???β	65.1%	161.5%	139.9%