Openzipkin conf: Zipkin at Yelp

1. Zipkin @ Prateek Agarwal @prat0318

2. - Prateek Agarwal - Software Engineer - Infrastructure team @ Yelp - Have worked on - python Swagger clients, - Zipkin infrastructure, - Maintaining Cassandra, ES clusters About me

3. Yelp’s Mission Connecting people with great local businesses.

4. Yelp Stats As of Q1 2016 90M 3270%102M

5. - Zipkin Infrastructure - pyramid_zipkin / swagger_zipkin - Lessons learned - Future plans Agenda

6. - 250+ services - We <3 Python - Pyramid/uwsgi framework - SmartStack for service discovery - Swagger for API schema declaration - Zipkin transport : Kafka | Zipkin datastore : Cassandra - Trace is generated on live traffic at a very very low % rate (0.005%) - Can also be generated on-demand by providing a particular query-param Infrastructure overview

7. Infrastructure overview Let’s talk about a scenario where service A calls B.

8. pyramid_zipkin - A simple decorator around every request - Able to handle scribe | kafka transport - Attaches a `unique_request_id` to every request - No changes needed in the service logic - Ability to add annotations using python’s `logging` module - Ability to add custom spans Service B pyramid_zipkin pyramid uwsgi

9. pyramid_zipkin Service B pyramid_zipkin pyramid uwsgi - Ability to add custom spans

10. swagger_zipkin - Eliminates the manual work of attaching zipkin headers - Decorates over swagger clients - swaggerpy (swagger v1.2) - bravado (swagger v2.0) Service A swagger_client swagger_zipkin

11. Lessons Learned - Cassandra is an excellent datastore for heavy writes - Typical prod writes/sec : 15k - It was able to even handle 100k writes/sec

12. Lessons Learned - Allocating offheap memory for Cassandra helped in reducing write latency by 2x - Pending compactions also went down.

13. Lessons Learned - With more services added, fetching from Kafka became a bottleneck - Solutions tried: - Adding more kafka partitions - Running more instances of collector - Adding multiple kafka consumer threads - with appropriate changes in openzipkin/zipkin - WIN - Batching up messages before sending to Kafka - with appropriate changes in openzipkin/zipkin - BIG WIN

16. Lessons Learned - With more services added, fetching from Kafka became a bottleneck - Solutions tried: - Running more instances of collector - Adding more kafka partitions - Adding multiple kafka consumer threads - with appropriate changes in openzipkin/zipkin - WIN - Batching up messages before sending to Kafka - with appropriate changes in openzipkin/zipkin - BIG WIN

17. Lessons Learned - With more services added, fetching from Kafka became a bottleneck - Solutions tried: - Running more instances of collector - Adding more kafka partitions - Adding multiple kafka consumer threads - with appropriate changes in openzipkin/zipkin - WIN - Batching up messages before sending to Kafka - with appropriate changes in openzipkin/zipkin - BIG WIN

18. Future Plans - To be used during deployments to check degradations - Validate the differences in number of downstream calls - Check against any new dependency sneaking in - Time differences in the spans - Create trace aggregation infrastructure using Splunk (wip) - A missing part of Zipkin - Redeploy zipkin dependency graph service after improvements - The service was unprovisioned because it created 100s of Gigs of /tmp files - These files got purged after the run (in ~1-2 hours) - Meanwhile, ops got alerted due to low disk space remaining - Didn’t give much of a value addition

19. @YelpEngineering fb.com/YelpEngineers engineeringblog.yelp.com github.com/yelp