Latency Problem Solved Go GC - Talkstalks.golang.org/2015/go-gc.pdf · 2019. 10. 10. · Tell...

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Go GC: Latency Problem Solved Rick Hudson Google Engineer GopherCon Denver July 8, 2015

Transcript of Latency Problem Solved Go GC - Talkstalks.golang.org/2015/go-gc.pdf · 2019. 10. 10. · Tell...

Page 1: Latency Problem Solved Go GC - Talkstalks.golang.org/2015/go-gc.pdf · 2019. 10. 10. · Tell people that GC is not a barrier with Go’s low latency GC Tune for even lower latency,

Go GC: Latency Problem SolvedRick HudsonGoogle Engineer

GopherCon DenverJuly 8, 2015

Page 2: Latency Problem Solved Go GC - Talkstalks.golang.org/2015/go-gc.pdf · 2019. 10. 10. · Tell people that GC is not a barrier with Go’s low latency GC Tune for even lower latency,

Google Confidential and Proprietary

My Codefendants: The Cambridge Runtime Gang

https://upload.wikimedia.org/wikipedia/commons/thumb/2/2f/Sato_Tadanobu_with_a_goban.jpeg/500px-Sato_Tadanobu_with_a_goban.jpeg

Page 3: Latency Problem Solved Go GC - Talkstalks.golang.org/2015/go-gc.pdf · 2019. 10. 10. · Tell people that GC is not a barrier with Go’s low latency GC Tune for even lower latency,

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Making Go Go: Establish A Virtuous Cycle

News Flash:2X Transistors != 2X Frequency

More transistors == more cores Only if software uses more cores

Long term Establish a virtuous cycle

Short term Increase Go Adoption

Software++

Hardware++

Hardware++

HW++

HW++

Software++

Software++

Software++

#1 Barrier: GC Latency

Page 4: Latency Problem Solved Go GC - Talkstalks.golang.org/2015/go-gc.pdf · 2019. 10. 10. · Tell people that GC is not a barrier with Go’s low latency GC Tune for even lower latency,

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When is the best time to do a GC?

When nobody is looking.

Using camera to track eye movement When subject looks away do a GC.

Recovering

https://upload.wikimedia.org/wikipedia/commons/3/35/Computer_Workstation_Variables.jpg

https://upload.wikimedia.org/wikipedia/commons/3/35/Computer_Workstation_Variables.jpg
https://upload.wikimedia.org/wikipedia/commons/3/35/Computer_Workstation_Variables.jpg
https://upload.wikimedia.org/wikipedia/commons/3/35/Computer_Workstation_Variables.jpg
Page 5: Latency Problem Solved Go GC - Talkstalks.golang.org/2015/go-gc.pdf · 2019. 10. 10. · Tell people that GC is not a barrier with Go’s low latency GC Tune for even lower latency,

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Waiting

Pop up a network wait icon

https://commons.wikimedia.org/wiki/File:WIFI_icon.svg#globalusage

https://commons.wikimedia.org/wiki/File:WIFI_icon.svg#globalusage
https://commons.wikimedia.org/wiki/File:WIFI_icon.svg#globalusage
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Or Trade Throughput for Reduced GC

Latency

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Latency

Nanosecond 1: Grace Hopper Nanosecond 11.8 inchesMicrosecond 5.4: Time light travels 1 mile in vacuumMillisecond 1: Read 1 MB sequentially from SSD 20: Read 1 MB from disk 50: Perceptual Causality (cursor response threshold) 50+: Various network delays 300: Eye blink

Page 8: Latency Problem Solved Go GC - Talkstalks.golang.org/2015/go-gc.pdf · 2019. 10. 10. · Tell people that GC is not a barrier with Go’s low latency GC Tune for even lower latency,

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Go isn’t Java: GC Related Go Differences

JavaTens of Java ThreadsSynchronization via objects/locksRuntime written in C

Objects linked with pointers

GoThousands of Goroutines Synchronization via channels Runtime written in Go

Leverages Go same as usersControl of spatial locality

Objects can be embeddedInterior pointers (&foo.field)

Let’s Build a GC for Go

Page 9: Latency Problem Solved Go GC - Talkstalks.golang.org/2015/go-gc.pdf · 2019. 10. 10. · Tell people that GC is not a barrier with Go’s low latency GC Tune for even lower latency,

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GC 101Scan Phase

Heap

Stacks/RegistersGlobals

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Mark Phase

Stacks/RegistersGlobals

Righteous Concurrent GC struggles with Evil Application changing pointers

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Sweep Phase

Stacks/RegistersGlobals

Page 12: Latency Problem Solved Go GC - Talkstalks.golang.org/2015/go-gc.pdf · 2019. 10. 10. · Tell people that GC is not a barrier with Go’s low latency GC Tune for even lower latency,

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GC Algorithm Phases

Off

Stack scan

Mark

Mark termination

Sweep

Off

Correctness proofs in literature (see me)

WB

on

STW

GC disabledPointer writes are just memory writes: *slot = ptr

Collect pointers from globals and goroutine stacksStacks scanned at preemption points

Mark objects and follow pointers until pointer queue is emptyWrite barrier tracks pointer changes by mutator

Rescan globals/changed stacks, finish marking, shrink stacks, …Literature contains non-STW algorithms: keeping it simple for now

Reclaim unmarked objects as neededAdjust GC pacing for next cycle

Rinse and repeat

Page 13: Latency Problem Solved Go GC - Talkstalks.golang.org/2015/go-gc.pdf · 2019. 10. 10. · Tell people that GC is not a barrier with Go’s low latency GC Tune for even lower latency,

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1.4 Stop the World

GCGC

Application Application

Page 14: Latency Problem Solved Go GC - Talkstalks.golang.org/2015/go-gc.pdf · 2019. 10. 10. · Tell people that GC is not a barrier with Go’s low latency GC Tune for even lower latency,

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Application

Application Application

Assist

GC

Application

Assist

GC

1 ms 3 ms

1.5 Concurrent GC

Page 15: Latency Problem Solved Go GC - Talkstalks.golang.org/2015/go-gc.pdf · 2019. 10. 10. · Tell people that GC is not a barrier with Go’s low latency GC Tune for even lower latency,

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Garbage Benchmark

9

8

7

6

5

4

3

2

1

0

GC

Pau

se (L

ower

is b

ette

r)

S

econ

ds

Heap Size (Gigabytes)

Page 16: Latency Problem Solved Go GC - Talkstalks.golang.org/2015/go-gc.pdf · 2019. 10. 10. · Tell people that GC is not a barrier with Go’s low latency GC Tune for even lower latency,

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1.5 Garbage Benchmark Latency

Heap Size (Megabytes)

GC

Pau

se (

Low

er is

Bet

ter)

Mill

isec

onds

1.5 GC Pauses

Page 17: Latency Problem Solved Go GC - Talkstalks.golang.org/2015/go-gc.pdf · 2019. 10. 10. · Tell people that GC is not a barrier with Go’s low latency GC Tune for even lower latency,

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GOGC=200

Heap Size (Megabytes)

Splay: Increasing Heap Size == Better Performance E

xecu

tion

Tim

e (L

ower

is B

ette

r)

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JSON: Increasing Heap Size == Better Performance

Heap Size (Megabytes)

GOGC=200

Exe

cutio

n Ti

me

(Low

er is

Bet

ter)

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Onward

Tell people that GC is not a barrier with Go’s low latency GC

Tune for even lower latency, higher throughput, more predictabilityFind the sweet spot.

1.6 work will be use case driven: Let’s talk.

Increase Go Adoption Establish Virtuous Cycle

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Questions


How Much Anonymity does Network Latency Leak? · How Much Anonymity Does Network Latency Leak? · 3 using a low-latency anonymity scheme: • A passive linkability attack. When latency

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EVA MUNNIK - Spectrum Lifestyle · palatijn r Trastevere OPMAAK K&C AKKOORD.indd 13 06-09-18 13:53. kids & the city 14 14 go’s & no-go’s – Go‘s • Zorg voor veel wisselgeld

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Stadtteil Bad Neuenahr Dienstleistung | Handwerk Einkaufen … · 2019. 7. 15. · Stand: April 2019 GC GC GC GC GC GC GC GC GC GC GC GC GC GC GC 41. Seidenblumenhaus Elfleur Telegrafenstraße

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GC AND GC/MS

GC AND GC/MS

GC-GEAR COUPLINGS - Deutsche Messe AGdonar.messe.de/exhibitor/hannovermesse/2017/K841192/gc-coupling... · 3 LINE-UP GC – Small Sizes GC-50 – GC-200 GC – Large Sizes GC-220

GC-GEAR COUPLINGS - Deutsche Messe AGdonar.messe.de/exhibitor/hannovermesse/2017/K841192/gc-coupling... · 3 LINE-UP GC – Small Sizes GC-50 – GC-200 GC – Large Sizes GC-220

Gc & gc vs hplc

Gc & gc vs hplc

Prépa Phase Exploration · latency Analysis latency Decision latency Action latency time Counter measure takes effect Counter measure approved Analysis completed Insights about the

Prépa Phase Exploration · latency Analysis latency Decision latency Action latency time Counter measure takes effect Counter measure approved Analysis completed Insights about the

High -Fidelity Latency Measurements in Low -Latency Networks

High -Fidelity Latency Measurements in Low -Latency Networks

GC and GC-MS

GC and GC-MS

superiorrestoration.comsuperiorrestoration.com/catalogs/enCTLG-DASH.pdf · BPT BULL-A CA-8 CB DDVD DRK-I DRK-s FW-G GC-16 GCC GC-C GC-C GC-GUN GC-GUN GC-KIT GC-KIT GC-TIPS GC-TIPS

superiorrestoration.comsuperiorrestoration.com/catalogs/enCTLG-DASH.pdf · BPT BULL-A CA-8 CB DDVD DRK-I DRK-s FW-G GC-16 GCC GC-C GC-C GC-GUN GC-GUN GC-KIT GC-KIT GC-TIPS GC-TIPS

Go GC: Latency Problem Solved

Go GC: Latency Problem Solved

GC Tooth MousserM GC Tooth MousserM GC Tooth MousserM

GC Tooth MousserM GC Tooth MousserM GC Tooth MousserM

Latency LTE

Latency LTE

MODEL: GC-269S GC-309B GC-269SA GC-309BA GC-269SV GC …

MODEL: GC-269S GC-309B GC-269SA GC-309BA GC-269SV GC …

srdf latency

srdf latency

Become a GC Hero · 2017. 7. 19. · Key Performance Indicators 1. Latency 2. Throughput 99.925% 3. Foot Print Memory: 2GB CPU: 30% GC event [s pause time Percentage of time spent

Become a GC Hero · 2017. 7. 19. · Key Performance Indicators 1. Latency 2. Throughput 99.925% 3. Foot Print Memory: 2GB CPU: 30% GC event [s pause time Percentage of time spent

VIRAL LATENCY

VIRAL LATENCY

1. Background - GitHub Pagesopeninx.github.io › ppt › HBASE-21879-document.pdf · 1. Background For reducing the Java GC impact to p99/p999 RPC latency, HBase 2.x has made an

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Real-World ADC Interrupt Latency...Preempt-RT Latency Benchmarking of the Cortex-A53 • Software and Hardware setup • Basic Latency Tests • UDP Ping Pong Ethernet Latency •

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Way To Go’s · 2013. 4. 1. · For most Mt. Baker students the idea of selling way-to-go’s is baffling, yet, an entire black market has formed under the subject. One seventh grade

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