Distributed tracing at Pinterest with new open source tools

Pinterest Engineering
9 min readadvanced
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Overview

The article discusses Pinterest's implementation of distributed tracing using their open-source tool, Pintrace, which tracks requests across microservices in their backend. It highlights the challenges of identifying latency issues and details the architecture and components of the tracing pipeline, including instrumentation, trace processing, and the Pintrace collector.

What You'll Learn

1

How to implement a distributed tracing pipeline using Pintrace

2

Why distributed tracing is essential for identifying latency issues in microservices

3

How to instrument Python and Java applications for tracing

4

When to use sampling in distributed tracing to reduce overhead

Prerequisites & Requirements

  • Understanding of microservices architecture and latency issues
  • Familiarity with Kafka and Spark(optional)

Key Questions Answered

What is Pintrace and how does it improve request tracking?
Pintrace is a distributed tracing pipeline developed by Pinterest that tracks requests across their Python and Java backend services. It provides fine-grained visibility into request execution, helping identify latency issues by capturing causality information and request latency data.
How does the Pintrace collector process spans from Kafka?
The Pintrace collector is a Spark job that reads spans from Kafka, aggregates them into traces, and stores them in an Elasticsearch backend. This allows for real-time analytics and efficient storage management by filtering and grouping spans based on trace IDs.
What role does the sampler play in the tracing process?
The sampler component in Pintrace decides which requests to trace, typically sampling 0.3% of all backend requests. This helps reduce the computational overhead and storage costs associated with capturing spans while still providing valuable insights.
What technologies are used in the Pintrace architecture?
Pintrace utilizes several technologies including Kafka for logging spans, Spark for processing and aggregating spans, and Elasticsearch for storing traces. These technologies work together to create a scalable and efficient tracing pipeline.

Key Statistics & Figures

Sampling rate for tracing requests
0.3 percent
This rate is typically used to reduce the computational overhead while still capturing valuable trace data.

Technologies & Tools

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Key Actionable Insights

1
Implementing distributed tracing can significantly enhance your ability to diagnose performance issues in microservices.
By using tools like Pintrace, you can gain detailed visibility into request flows and identify bottlenecks that affect user experience.
2
Utilize sampling effectively to manage overhead while still capturing essential trace data.
Adjusting the sampling rate allows you to balance the need for detailed insights with the performance impact of tracing.
3
Contributing to open-source projects can foster community collaboration and improve your tools.
By open-sourcing Pintrace, Pinterest encourages contributions that can enhance the tool's capabilities and benefit the broader engineering community.

Common Pitfalls

1
Failing to properly instrument all necessary services can lead to incomplete trace data.
Without comprehensive instrumentation, you may miss critical insights into request flows, making it difficult to diagnose performance issues effectively.
2
Over-sampling can lead to excessive overhead and storage costs.
It's important to find a balance in sampling rates to ensure you capture enough data for analysis without overwhelming your systems.

Related Concepts

Distributed Tracing
Microservices Architecture
Performance Monitoring
Real-time Analytics