How Can I Capture Stack Traces from Panics in Go?

Retrieving Stack Traces from Panics

Panics in Go generate valuable stack traces displayed on stdout. However, when recovering from a panic, only an error message is returned, limiting debugging capabilities.

This article explores the possibility of storing the panic's stack trace for enhanced debugging.

Solution: Utilizing the Runtime/Debug Package

As suggested by Volker and mentioned in the comments, Go's runtime/debug package provides the functionality to capture stack traces. Here's a code example demonstrating its usage:

package main

import (
    "fmt"
    "runtime/debug"
)

func main() {
    // Define a deferred function to recover from the panic and store the stack trace.
    defer func() {
        if r := recover(); r != nil {
            stacktrace := string(debug.Stack())
            fmt.Println("Stack trace from panic:\n", stacktrace)
        }
    }()

    // Panic with an out-of-range index access.
    var mySlice []int
    var index = 0
    _, _ = mySlice[index]

    fmt.Println("This line will never run after the panic!")
}

When you run this code, it prints the stack trace from the panic:

Stack trace from panic:
goroutine 1 [running]:
runtime/debug.Stack(0x1fd66a1e, 0x741000, 0x229080, 0xd92df0)
    /usr/lib/go/src/runtime/debug/stack.go:24 +0xc0
main.main.func1()
    /home/user/go/src/example.com/myapp/main.go:14 +0x60
panic(0x1feed5f8, 0xd92df0)
    /usr/lib/go/src/runtime/panic.go:562 +0x2c0
main.main()
    /home/user/go/src/example.com/myapp/main.go:20 +0x132

This output provides the line in the source code (main.go:14) that caused the panic, making it easier to identify the cause.

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