How Can I Capture and Store the Stack Trace of a Panic in Go?

Retrieving and Storing Panic Stack Traces

When a panic occurs in a Go program, a stack trace providing valuable debugging information is automatically printed to standard output. However, when recovering from a panic, recover() only returns an error string indicating the cause of the panic.

This raises the question of whether it's possible to store the printed stack trace for further analysis.

Solution: Utilizing the Runtime/Debug Package

To address this issue, we can leverage the runtime/debug package. By wrapping our code in a deferred function that invokes recover(), we can capture the panic and access the stack trace using debug.Stack().

Below is an example code snippet showcasing this approach:

package main

import (
    "fmt"
    "runtime/debug"
)

func main() {
    defer func() {
        if r := recover(); r != nil {
            fmt.Println("stacktrace from panic: \n" + string(debug.Stack()))
        }
    }()

    var mySlice []int
    j := mySlice[0]

    fmt.Printf("Hello, playground %d", j)
}

When run, this code will output the following stack trace upon panicking:

stacktrace from panic:
goroutine 1 [running]:
runtime/debug.Stack(0x1042ff18, 0x98b2, 0xf0ba0, 0x17d048)
    /usr/local/go/src/runtime/debug/stack.go:24 +0xc0
main.main.func1()
    /tmp/sandbox973508195/main.go:11 +0x60
panic(0xf0ba0, 0x17d048)
    /usr/local/go/src/runtime/panic.go:502 +0x2c0
main.main()
    /tmp/sandbox973508195/main.go:16 +0x60

This stack trace provides a detailed view of the function call chain leading up to the panic, making it easier to pinpoint the source of the error.

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