go gc algorithm 101

©2019 Wantedly, Inc. Go GC algorithm 101 Go Conference 2019
Autumn Oct 28, 2019 - Takuma Shiotsu(@taxio_tech)

©2019 Wantedly, Inc. ࣗݾ঺հ ‣ Wantedly. Inc. 20ଔ಺ఆऀ ‣ ژ౎޻ܳણҡେֶେֶӃ
M2 - ιϑτ΢ΣΞ޻ֶݚڀࣨ 5BLVNB4IJPUTV !UBYJP@UFDI

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3FMFBTF/PUFͷ3VOUJNFͷ߲໨Λ ϫΫϫΫ͠ͳ͕ΒோΊΔ͖͔͚ͬΛ࣋ͭ

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ߏ੒͢Δཧ࿦ͱ࣮૷ʯ ‣ தଜ੒༸ FUD ʮΨϕʔδίϨΫγϣϯͷΞϧΰϦζϜͱ࣮૷ʯ w ॻ੶΍ϒϩάΛެ։͍ͯͩͬͯ͘͠͞Δํʑɼ ͦͯ͠ԿΑΓ(PͷDPOUSJCVUPSͷํʑʹਂ͘ײँ͠·͢

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w ࿩͞ͳ͍͜ͱ ‣ (P͕࠾༻͍ͯ͠ͳ͍ଞͷ($ΞϧΰϦζϜ ‣ ώʔϓߏ଄ɼ"MMPDBUJPO΍&TDBQFղੳͷ࿩

©2019 Wantedly, Inc. "HFOEB w ࠓ೔ͷηογϣϯͷྲྀΕ ‣ ($ͷجૅͷઆ໌ ‣ (Pͱ.BSL4XFFQ($
‣ (Pͱ$PODVSSFOU.BSL4XFFQ($ w ཧ࿦࣮૷ཧ࿦࣮૷ͷॱͰઆ໌͍͖ͯ͠·͢

©2019 Wantedly, Inc. ($ͱ͸ʁ w (BSCBHF$PMMFDUJPO w ώʔϓྖҬʹ֬อ͞Εͨɼ ΋͏࢖ΘΕͳ͍Ͱ͋Ζ͏ϝϞϦΛղ์͢Δ w
(PͰ͸3VOUJNFʹ౥ࡌ͞Ε͍ͯΔ

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‣ GOGCɼGODEBUGʹ৭ʑ ‣ IUUQTRJJUBDPNNBUUOJUFNTFDGG

©2019 Wantedly, Inc. ($ͷجૅ༻ޠ w ΦϒδΣΫτ ‣ ώʔϓྖҬ͔Β֬อ͢Δ σʔλߏ଄ͷ୯Ґ ‣
ϔομΦϒδΣΫτͷϝλ৘ใ ‣ ϑΟʔϧυ஋΍ଞͷΦϒδΣΫτͷࢀর w ϛϡʔςʔλ ‣ ΦϒδΣΫτͷੜ੒ "MMPDBUJPO ΍ ߋ৽Λߦ͏ )FBEFS 'JFMET

©2019 Wantedly, Inc. ($ͷجૅ༻ޠ w 3PPU ‣ ΦϒδΣΫτͷࢀরؔ܎Λ௥͏ͨΊͷ࢝఺ ‣ TUBDL΍TUBUJDྖҬʹอ࣋͞ΕΔม਺ͳͲ
‣ 3PPUʹଘࡏ͢ΔΦϒδΣΫτΛ3PPUΦϒδΣΫτͱݴ͏ w ࢮΜͰ͍ΔΦϒδΣΫτ ‣ 3PPU͔ΒḷΕͳ͍ΦϒδΣΫτ͸΋͏࢖ΘΕͳ͍͸ͣ ͜ΕΛճऩ͍ͨ͠ %FBE 3PPU

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ಈ͖ଓ͚ΔϛϡʔςʔλͱͲ͏͍͏࿈ܞΛऔΔͷ͔ w ධՁ࣠ ‣ -BUFODZϛϡʔςʔλͷ ࠷େ ఀࢭ࣌ؒ ‣ 5ISPVHIQVU୯Ґ࣌ؒ͋ͨΓͷώʔϓαΠζॲཧೳྗ ‣ ଞʹ΋ώʔϓྖҬͷঢ়ଶʹ͍͔ؔͯͭ͘͠

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$PNNVOJDBUJPOPGUIF"$. "QS w ͭͷϑΣʔζ͔Β੒Δ ‣ ੜ͖͍ͯΔΦϒδΣΫτΛ୳͢.BSLϑΣʔζ ‣ ࢮΜͰ͍ΔΦϒδΣΫτΛճऩ ղ์ ͢Δ4XFFQϑΣʔζ w ($͕ىಈ͔ͯ͠Βऴྃ͢Δ·Ͱɼϛϡʔςʔλ͸ಈ࡞͠ͳ͍ ‣ 458 4UPQ5IF8PSME ‣ ͜Ε͕MBUFODZͷओͳཁҼ

©2019 Wantedly, Inc. .BSLϑΣʔζ w ੜ͖͍ͯΔΦϒδΣΫτΛݟ͚ͭΔϑΣʔζ w 3PPU͔Β୳ࡧ͍͖ͯ͠ɼ ݟ͚ͭͨΦϒδΣΫτͷϔομʹ.BSLΛ෇͚͍ͯ͘ ✔
✔ ✔ Root

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‣ ࣍ͷ"MMPDBUJPOʹ࢖͏ͨΊͷ४උ ‣ ྫ͑͹GSFFͳPCKFDUΛ؅ཧ͓ͯ͘͠Ϧετʹ௥Ճ ✔ ✔ ✔ Heap

©2019 Wantedly, Inc. .BSL4XFFQ($ w ϝϦοτ ‣ ୯७Ͱൺֱత࣮૷͕؆୯ w σϝϦοτ
‣ ϝϞϦͷஅยԽ ϑϥάϝϯςʔγϣϯ ‣ ௿଎ͳ"MMPDBUJPO ‣ 458ͷӨڹͰMBUFODZ͕େ͖͍

©2019 Wantedly, Inc. (Pͱ.BSL4XFFQ($ w (P·Ͱओʹ͜ͷΞϧΰϦζϜ w લճͷ($ͰNBSLͨ͠ੜଘΦϒδΣΫτͷ૯αΠζ
GOGC ͷϝϞϦ͕৽͘͠"MMPDBUF͞Εͨͱ͖ʹىಈ ‣ NBSLࡁΈ૯αΠζͷॳظ஋͸.# ‣ GOGC=offͷ৔߹($͸ىಈ͠ͳ͍ w ΋ͪΖΜ͜Ε͚ͩͩͱ஗͍ͷͰɼ ͍ͭ͘΋޻෉͕੝Γࠐ·Ε͍ͯΔ ‣ #JUNBQNBSLJOH 1BSBMMFMJNQM 5$.BMMPD FUD

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.BSLϑϥάΛ໭͢ͷָ͕ ‣ $PQZPO8SJUFͱͷ૬ੑ͕͍͍

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ࣦΘΕͳ͍Α͏ʹ͢Δ ‣ ࠷ऴతʹ($Λ׬ྃ͢Δ w Ͳ͏΍ͬͯ͜ΕΒΛຬͨ͠ͳ͕Βฒߦ࣮ߦ͢Δͷ͔ʁ ‣ ৭NBSLJOH ‣ 8SJUFCBSSJFS

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NBSLແ͠ ‣ փ୳ࡧத NBSLࡁΈϦετʹೖΕ͓ͯ͘ ‣ ࠇ୳ࡧࡁΈ NBSLࡁΈϦετʹແ͍ w Ϧετ͔ΒΦϒδΣΫτͷࢀরΛऔΓग़͠ɼ ͦͷGJFMEΛ୳ࡧ͍ͯ͘͠ ‣ (PͰ͸RVFVFͱ࣮ͯ͠૷͞Ε͍ͯΔ Root

©2019 Wantedly, Inc. 8SJUFCBSSJFS w ΦϒδΣΫτ͕໎ࢠʹͳΔ৚݅ ‣ ϛϡʔςʔλ͕നΦϒδΣΫτ΁ͷϙΠϯλΛ ࠇΦϒδΣΫτʹॻ͖ࠐΉ
શͯͷփ৭ΦϒδΣΫτ͔Βͷɼ ͦͷനΦϒδΣΫτ΁ͷܦ࿏͕ଘࡏ͠ͳ͍ w ͜ͷ৚͕݅ୡ੒͞Εͳ͍Α͏ʹ ϛϡʔςʔλͷΦϒδΣΫτૢ࡞ʹҰఆͷॲཧΛڬΉ ‣ ৭ʑͳख๏͕͋Δ ‣ (P͕࠾༻͍ͯ͠Δख๏͸ޙͰղઆ

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3PPUΦϒδΣΫτΛશͯփ৭ʹృΔ SVOUJNFͷ($ʹඞཁͳ͋Ε͜ΕͷॳظԽ ‣ $PODVSSFOUNBSL ‣ .BSLUFSNJOBUJPO 458 ඞཁͳ৔߹͸3PPUΛ࠶૸ࠪ ‣ $PODVSSFOUTXFFQ ‣ 4XFFQUFSNJOBUJPO 458

©2019 Wantedly, Inc. $PODVSSFOU.BSL4XFFQ($ w ϝϦοτ ‣ 458࡟ݮʹΑͬͯMBUFODZ͕ݮΔ w σϝϦοτ
‣ 8SJUFCBSSJFSʹΑͬͯεϧʔϓοτ͕Լ͕Δ

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փPSࠇ ৔߹͸Կ΋͠ͳ͍ Ͳ͔͔͜Βͷࢀর

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w SFGHJUIVCDPNHPMBOHHPCMPCFBTSD SVOUJNFNCBSSJFSHP

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.BSL .BSLUFSNJOBUJPO 4XFFQ w SFGHJUIVCDPNHPMBOHHPCMPCFBTSD SVOUJNFNHDHP

©2019 Wantedly, Inc. .BSLUFSNJOBUJPO w 458 w NBSLϑΣʔζͷޙॲཧ ‣ gcphase_GCmark_GCmarktermination
‣ "TTJTUͳͲͷແޮԽ ‣ ࣍ͷ($ىಈ༻ͷώʔϓαΠζΛࢉग़

©2019 Wantedly, Inc. 4XFFQ w લॲཧ ‣ gcphase_GCmarktermination_GCoff ‣ 8SJUFCBSSJFSΛແޮԽ
w (P͸5$.BMMPDΛϕʔεͱͨ͠"MMPDBUJPOػߏ ‣ ίϨΫλ͕·ͩݟ͍ͯͳ͍ྖҬʹΦϒδΣΫτΛ֬อ͠ͳ͍Α ͏ʹɼ"MMPDBUJPO͢ΔલʹͦͷαΠζͷQBHFͷTXFFQॲཧΛ ਐΊ͓ͯ͘ ɾɾɾ ͜͜·ͰͷྖҬͳΒ  നΦϒδΣΫτΛ֬อͯ͠΋େৎ෉ Heap (Page)

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IUUQTCMPHHPMBOHPSHJTNNLFZOPUF *4.. ‣ ϨΠςϯγ͸Լ͕Δ͕8SJUFCBSSJFSʹΑͬͯɼ εϧʔϓοτ͕Լ͕ΔՄೳੑ͕͋Δ w ۩ମతͳٞ࿦͸·ͩݟ౰ͨΒͳ͍ ݟ͚ͭͯͳ͍ ͕ɼ (PͳͲͰͲ͏มΘָ͍͔͕ͬͯ͘͠Έ

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w ($͸੒௕͠ଓ͚͍ͯΔ ‣ 3FMFBTFOPUF΍1SPQPTBMΛಡΉͷָ͕͠ΈͰ͢Ͷ

go gc algorithm 101

go gc algorithm 101

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