We started to shard on 1,000,000 daily users and no cache (Splash 2011)

Who is that guy? Jesper Richter-‐Reichhelm Twi1er: @jrirei Head of Engineering wooga Berlin, Germany

wooga is #3 game developer on Facebook

Wooga has dedicated game teams Cooming soon

Flash client sends state changes to backend Flash client Ruby backend

Social games need to scale quite a bit 400 million PIs / month

Social games need to scale quite a bit 14 billion requests / month

Social games need to scale quite a bit 14 billion requests / month 100,000 DB operaKons / second

Social games need to scale quite a bit 14 billion requests / month 50,000 DB updates / second

Social games need to scale quite a bit 14 billion requests / month 50,000 DB updates / second no cache

A journey to 1,000,000 daily users Start of the journey 6 weeks of pain Paradise Conclusion

October 2009: wooga’s ﬁrst simulaKon game

Instead of PHP we used Ruby

Our database was MySQL

Our database was MySQL even user ids odd user ids

And we went into the cloud

Master-‐slave replicaKon for DBs worked ﬁne lb app app app db db

We added a few applicaKon servers over Kme lb app app app app app app app app app db db

250K daily users and no problems&$!!!$!!!"%$#!!$!!!"%$!!!$!!!" #!!$!!!" Life was good !" ()*%!" +,-*%!" ./0*%!" +12*%%" ()*%%" +,-*%%" ./0*%%"

Life was well and I went on a nice vacaKon TO DO <picture: Jesper in clot canyon>

Our bane: MySQL hiccups (!!"# !"# &!"# %!"# $!"# !"# !# )# (!# ()# $!# $)# *!# *)# %!#

A journey to 1,000,000 daily users Start of the journey 6 weeks of pain Paradise Conclusion

SQL queries generated by Rubyamf gem AMF responses to Flash client

SQL queries generated by Rubyamf gem AMF responses to Flash client Wrong conﬁg... ... so associated data was included, too

SQL queries generated by Rubyamf gem AMF responses to Flash client Wrong conﬁg... ... so associated data was included, too => Easy to ﬁx

More traﬃc using the same cluster lb app app app app app app app app app db db

Config tweaks brought us to 300K DAU&$!!!$!!!"%$#!!$!!!"%$!!!$!!!" #!!$!!!" Config fixes !" ()*%!" +,-*%!" ./0*%!" +12*%%" ()*%%" +,-*%%" ./0*%%"

AcKveRecord’s checks caused 20% extra DB Checking connecKon state MySQL process list full of ‘status’ calls

AcKveRecord’s checks caused 20% extra DB Checking connecKon state MySQL process list full of ‘status’ calls => Fixed by 1 line of code

I/O on MySQL masters sKll was the bo^leneck New Relic: 60% of all UPDATEs on ‘Kles’ table

Tiles are part of the core game loop Core game loop 1) plant 2) wait 3) harvest

We started to shard on model, too Adding new shards old old master slave

We started to shard on model, too Adding new shards 1) Setup new masters as slaves of old ones old old new master slave master

We started to shard on model, too Adding new shards 1) Setup new masters old old new new master slave master slave

We started to shard on model, too Adding new shards 1) Setup new masters 2) Start using new masters old old new new master slave master slave

We started to shard on model, too Adding new shards 1) Setup new masters 2) Start using new masters 3) Cut replica<on old old new new master slave master slave

We started to shard on model, too Adding new shards 1) Setup new masters 2) Start using new masters 3) Cut replica<on 4) Truncate old old new new master slave master slave

4 DB masters and a few more servers lb app app app app app app app app app app app app app app app app <les <les db db db db

Sharding by model brought us to 400K DAU&$!!!$!!!"%$#!!$!!!"%$!!!$!!!" #!!$!!!" Shard by model !" ()*%!" +,-*%!" ./0*%!" +12*%%" ()*%%" +,-*%%" ./0*%%"

We improved our MySQL setup RAID-‐0 of EBS volumes

We improved our MySQL setup RAID-‐0 of EBS volumes Using XtraDB

We improved our MySQL setup RAID-‐0 of EBS volumes Using XtraDB Tweaking my.cnf

Sharding gem circumvented AR’s internal cache AcKveRecord caches SQL queries...

Sharding gem circumvented AR’s internal cache AcKveRecord caches SQL queries... ... only in our development environment!

Sharding gem circumvented AR’s internal cache AcKveRecord caches SQL queries... ... only in our development environment! => Fixed by 2 lines of code

I/O sKll was not fast enough If 2 + 2 is not enough, ...

I/O sKll was not fast enough If 2 + 2 is not enough, ... … perhaps 4 + 4 masters will do?

It’s no fun to handle 8+8 MySQL DBs lb app app app app app app app app app app app app app app app app app app <les <les db db db db

It’s no fun to handle 8+8 MySQL DBs lb app app app app app app app app app app app app app app app app app app <les <les <les <les db db db db db db db db

At 500K DAU we were at a dead end&$!!!$!!!"%$#!!$!!!"%$!!!$!!!" #!!$!!!" !" ()*%!" +,-*%!" ./0*%!" +12*%%" ()*%%" +,-*%%" ./0*%%"

I/O remained bo^leneck for MySQL UPDATEs Each DB master could do about 1000 DB write/s.

I/O remained bo^leneck for MySQL UPDATEs Each DB master could do about 1000 DB write/s. That’s not enough!

Pick the right tool for the job!

Redis is fast but goes beyond simple key/value Redis is a key-‐value store Hashes, Sets, Sorted Sets, Lists Atomic opera<ons like set, get, increment

Redis is fast but goes beyond simple key/value Redis is a key-‐value store Hashes, Sets, Sorted Sets, Lists Atomic opera<ons like set, get, increment 50,000 transacKons/s on EC2 Writes are as fast as reads

Wooga has dedicated game teams

Shelf Kles : An ideal candidate for using Shelf Kles: { plant1 => 184, plant2 => 141, plant3 => 130, plant4 => 112, … }

Shelf Kles : An ideal candidate for using Redis Redis Hash HGETALL HGETHSET HINCRBY …

Migrate on the ﬂy when accessing new model

Migrate on the ﬂy -‐ but only once true if id could be added else false

Typical migraKon throughput over 3 days

Migrate on the ﬂy -‐ and clean up later 1. Let migraKon run unKl everything cools down

Migrate on the ﬂy -‐ and clean up later 1. Let migraKon run unKl everything cools down 2. Migrate the rest manually

Migrate on the ﬂy -‐ and clean up later 1. Let migraKon run unKl everything cools down 2. Migrate the rest manually 3. Remove migraKon code

Migrate on the ﬂy -‐ and clean up later 1. Let migraKon run unKl everything cools down 2. Migrate the rest manually 3. Remove migraKon code 4. Wait unKl no fallback necessary

Migrate on the ﬂy -‐ and clean up later 1. Let migraKon run unKl everything cools down 2. Migrate the rest manually 3. Remove migraKon code 4. Wait unKl no fallback necessary 5. Remove SQL table

A journey to 1,000,000 daily users Start of the journey 6 weeks of pain Paredise (or not?) Conclusion

Again: Tiles are part of the core game loop Core game loop 1) plant 2) wait 3) harvest

Size ma^ers for migraKons MigraKon check overload Migra<on only on startup

Size ma^ers for migraKons MigraKon check overload Migra<on only on startup Overlooked an edge case Only migrate 1% of users Con<nue if everything is ok

In-‐memory DBs don’t like to dump to disk Dumping to disk SAVE is blocking BGSAVE needs free RAM

In-‐memory DBs don’t like to dump to disk Dumping to disk SAVE is blocking BGSAVE needs free RAM Latency increase by 100%

In-‐memory DBs don’t like to dump to disk Dumping to disk SAVE is blocking BGSAVE needs free RAM Latency increase by 100% => BGSAVE on slaves every 15 minutes

Redis replicaKon starts with a BGSAVE BGSAVE on master Slave imports dumped ﬁle

Redis replicaKon starts with a BGSAVE BGSAVE on master Slave imports dumped ﬁle => No RAM means no new slaves

Redis had a memory fragmenKon problem 44 GB in 8 days 24 GB

Redis had a memory fragmenKon problem 38 GB in 3 days 24 GB

If MySQL is a truck Fast enough Disk based Robust Fast enough disk based robust

If MySQL is a truck, Redis is a race car Super fast RAM based Fragile Super fast RAM based fragile

Big and staKc data in MySQL, rest goes to Redis 256 GB data 60 GB data 10% writes 50% writes hSp://www.ﬂickr.com/photos/erix/245657047/

Lots of boxes, but automaKon helps a lot! lb lbapp app app app app app app app app app app app appapp app app app app app app app app app app app appapp app app app app app app app app app app app appdb db db db db redis redis redis redis redis

We reached 1 million daily users!&$!!!$!!!"%$#!!$!!!"%$!!!$!!!" 1,000,000 -‐ Big party! #!!$!!!" !" ()*%!" +,-*%!" ./0*%!" +12*%%" ()*%%" +,-*%%" ./0*%%"

We started archiving inacKve users&$!!!$!!!"%$#!!$!!!" 50% DB%$!!!$!!!" reducKon #!!$!!!" !" ()*%!" +,-*%!" ./0*%!" +12*%%" ()*%%" +,-*%%" ./0*%%"

We even survived a complete data center loss&$!!!$!!!" EBS no%$#!!$!!!" more!%$!!!$!!!" #!!$!!!" !" ()*%!" +,-*%!" ./0*%!" +12*%%" ()*%%" +,-*%%" ./0*%%"

We improved our MySQL schema on-‐the-‐ﬂy&$!!!$!!!" 30% DB%$#!!$!!!" reducKon%$!!!$!!!" #!!$!!!" !" ()*%!" +,-*%!" ./0*%!" +12*%%" ()*%%" +,-*%%" ./0*%%"

Will we reach 2 million daily users?&$!!!$!!!"%$#!!$!!!"%$!!!$!!!" #!!$!!!" !" ()*%!" +,-*%!" ./0*%!" +12*%%" ()*%%" +,-*%%" ./0*%%"

A journey to 1,000,000 daily users Start of the journey 6 weeks of pain Paredise (or not?) Conclusion

You do not know the future Plan ahead

You do not know the future Plan ahead Learn

You do not know the future Plan ahead Learn Adapt

EvoluKon every week EVOLUTION of sonware &$!!!$!!!" %$#!!$!!!" %$!!!$!!!" #!!$!!!" !" ()*%!" +,-*%!" ./0*%!" +12*%%" ()*%%" +,-*%%" ./0*%%"

EvoluKon every week EVOLUTION of sonware

EvoluKon every week, RevoluKon if necessary REVOLUTION of sonware

EvoluKon every week, RevoluKon if necessary REVOLUTION of sonware &$!!!$!!!" %$#!!$!!!" %$!!!$!!!" #!!$!!!" !" ()*%!" +,-*%!" ./0*%!" +12*%%" ()*%%" +,-*%%" ./0*%%"

Each new game is a revoluKon

Each new game is a revoluKon Cooming soon

Works for teams ...

Works for teams and for companies !""#$%&"()"*+,

Thank you!Jesper Richter-‐Reichhelm @jrirei slideshare.net/wooga wooga.com/jobs