golang

Profiling Go Services with pprof

LeetCode

— 1 min read

What Is Profiling and Why Should You Care?

Imagine your Go application is like a car. Profiling is like running a diagnostic test to find out why your car is slow or using too much fuel. In programming terms, profiling helps you understand which parts of your code are using the most CPU time or memory.

Meet pprof: Your Go Profiling Tool

pprof is a built-in tool in Go that helps you analyze your program's performance. It's like having a mechanic's toolkit for your code. You can use it to:

  • Find slow functions (CPU profiling)
  • Detect memory leaks (memory profiling)
  • See where goroutines are stuck (block profiling)

How to Start Profiling with pprof

Using pprof is surprisingly simple. Here's how to add it to your Go service:

Step 1: Import the Package

import _ "net/http/pprof"

Step 2: Start Your HTTP Server

go func() {
    log.Println(http.ListenAndServe("localhost:6060", nil))
}()

Real-World Example: Finding a Performance Problem

Let's say you have a web service that's running slowly. Here's how you'd use pprof to investigate:

1. Generate Some Load

First, use a tool like curl or your browser to hit your endpoints and create some activity.

2. Capture the Profile

go tool pprof http://localhost:6060/debug/pprof/profile?seconds=30

3. Analyze the Results

pprof will show you a list of functions ordered by how much CPU time they use. The ones at the top are your bottlenecks!

Understanding pprof Output

When you run pprof, you'll see information like:

  • Flat: Time spent in the function itself
  • Cum: Time spent in the function plus functions it calls
  • %: Percentage of total time

Different Types of Profiles

pprof can show you different aspects of your program:

CPU Profile

Shows which functions are using the most processor time.

Memory Profile

Reveals where your program is allocating memory.

Block Profile

Helps find where goroutines are getting stuck.

Visualizing the Data

pprof can generate visual graphs that make it easier to understand relationships:

go tool pprof -http=:8080 profile.out

When to Use Profiling

Consider using pprof when:

  • Your service is slower than expected
  • Memory usage keeps growing (possible leak)
  • You're optimizing performance before a big release

Tips for Effective Profiling

  • Profile in production-like environments
  • Compare before/after when making optimizations
  • Focus on the biggest bottlenecks first

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