Tian-Ying ChangStorage & Caching, Engineering @ Pinterest

Removable SingularityA Story of HBase Upgrade at Pinterest

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AgendaUsage of HBase in PinterestUpgrading Situation and ChallengesMigration StepsPerformance TuningFinal Notes

HBase @ Pinterest§Early applications: homefeed, search & discovery§UserMetaStore: a generic store layer for all applications using user

KV data§Zen: a graph service layer• Many applications can be modeled as graph• Usage of HBase flourished after Zen release

§Other misc. use cases, e.g., analytics, OpenTSDB

40+ HBase clusters on 0.94

Need Upgrading§HBase 0.94 is not supported by community anymore§Newer version has better reliability, availability and

performance§Easier to contribute back to community

Singularity of HBase 0.96§RPC protocol changes§Data format changes§HDFS folder structure changes

§API changes§Generally considered “impossible” to live upgrade without

downtime

http://blog.cloudera.com/blog/2012/06/the-singularity-hbase-compatibility-and-extensibility/

The Dilemma§Singularity: cannot live upgrade from HBase 0.94 to later

version• Need downtime

§Pinterest hosts critical online real time services on HBase• Cannot afford downtime

§Stuck?

Fast Forward§Successfully upgraded production clusters last year• Chose one of the most loaded clusters as pilot• No application redeploy needed on the day of switching

to 1.2 cluster• Live switch with no interrupt to Pinterest site

§Big performance improvement

P99 L

atenc

y of D

iffere

nt A

PIs

Point of Live Switch

How did we do it?

ZKClient

read/write

HBase 0.94

ZKClient

read/write

HBase 0.94 HBase 0.94nativereplication

ZKClient

read/write

HBase 0.94 HBase 0.94nativereplication

ZKClient

read/write

HBase 0.94

ZKClient

read/write

HBase 0.94 HBase 0.94

1. Build empty cluster

ZKClient

read/write

HBase 0.94 HBase 0.94nativereplication

1. Build empty cluster

2. Setup replication

ZKClient

read/write

HBase 0.94 HBase 0.94nativereplication

1. Build empty cluster

2. Setup replication

3. Export snapshot

ZKClient

read/write

HBase 0.94 HBase 0.94nativereplication

1. Build empty cluster

2. Setup replication

3. Export snapshot4. Recover table from snapshot

ZKClient

read/write

HBase 0.94 HBase 0.94nativereplication

1. Build empty cluster

2. Setup replication

3. Export snapshot4. Recover table from snapshot

5. Replication drain

ZKClient

read/write

HBase 0.94 HBase 0.94nativereplication

ZKClient

read/write

HBase 0.94 HBase 1.2replication

ZKClient

read/write

HBase 0.94 HBase 1.2replication

ZKClient

read/write

HBase 0.94HBase 0.94

ZKClient

read/write

HBase 0.94 HBase 1.2

1. Build empty cluster

HBase 0.94

ZKClient

read/write

HBase 0.94 HBase 1.2non-nativereplication

1. Build empty cluster

2. Setup replication

HBase 0.94

ZKClient

read/write

HBase 0.94 HBase 1.2non-nativereplication

1. Build empty cluster

2. Setup replication

3. Export snapshot

HBase 0.94

ZKClient

read/write

HBase 0.94 HBase 1.2non-nativereplication

1. Build empty cluster

2. Setup replication

3. Export snapshot4. Recover 1.2 table from 0.94 snapshot

HBase 0.94

ZKClient

read/write

HBase 0.94 HBase 1.2non-nativereplication

1. Build empty cluster

2. Setup replication

3. Export snapshot4. Recover table from snapshot

5. Replication drain

HBase 0.94

ZKClient

read/write

HBase 0.94 HBase 1.2non-nativereplicationHBase 0.94

Major Problems to Solve

Client able to talk to both 0.94 and 1.2 automatically

Data can be replicated between HBase 0.94 and 1.2 bi-directional

AsyncHBase Client§Chose AsyncHBase due to better throughput and latency• Stock AsyncHBase 1.7 can talk to both 0.94 and later version by

detecting the HBase version and use different protocol

§But cannot directly use stock AsyncHBase 1.7• We made many private improvements internally• Need to make those private features work with 1.2 cluster

AsyncHBase Client Improvements§ BatchGet (open sourced in tsdb 2.4)§ SmallScan§ Ping feature to handle AWS network issue§ Pluggable metric framework§ Metrics broken down by RPC/region/RS

• Useful for debugging issues with better slice and dice § Rate limiting feature

• Automatically throttle/blacklist requests based on, e.g., latency• Easier and better place to do throttling than at HBase RS side

§ In progress to open source

Live Data Migration§Export snapshots from 0.94, recover tables in 1.2• Relatively easy since we were already doing it between 0.94 and 0.94• Modifying our existing DR/backup tool to work between 0.94 and

1.2

§Bidirectional live replication between 0.94 and 1.2 • Breaking changes in RPC protocol means native replication does not

work• Using thrift replication to overcome the issue

Thrift Replication§Patch from Flurry HBASE-12814§Fixed a bug in the 0.98/1.2 version

• Threading bug exposed during prod data testing with high write QPS• Fixed by implementing thrift client connection pool for each replication sink• Fix also made the replication more performant

§Bidirectional is needed for potential rollback§Verification!!

• Chckr: tool for checking data replication consistency between 0.94 and 1.2 cluster• Used a configurable timestamp parameter to eliminate false positive caused by

replication delay

Upgrade Steps (Recap)§Build new 1.2 empty cluster§Set up master/master thrift replication between 0.94 and 1.2§Export snapshot from 0.94 into 1.2 cluster§Recover table in 1.2 cluster§Replication draining§Monitor health metrics§Switch client to use 1.2 cluster

Performance§Use production dark read/write traffic to verify performance§Measured round trip latency from AsyncHBase layer• Cannot do server latency compare since 1.2 has p999 server side

latency, while 0.94 does not• Use metric breakdown by RPS/region/RS with Ostrich

implementation to compare performance

Get

BatchGet

Put

CompAndSet

Delete

Read Performance§Default config has worse p99 latency **• Bucket cache hurts p99 latency due to bad GC

§Short circuit read helps latency§Use CMS instead of G1GC§Native checksum helps latency

* *The read path off-heap feature from 2.0 should help a lot. HBASE-17138

Write Performance§Use write heavy load user case to expose perf issues §Metrics shows much higher wal sync ops than 0.94§Disruptor based wal sync implementation caused too much wal

sync operation§hbase.regionserver.hlog.syncer.count default is 5, changed to 1

Thanks!

Community helps from Michael Stack and Rahul Gidwani

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