How can I retrieve and store the stacktrace of a Go panic for more detailed debugging?

Retrieving and Storing Stacktraces of Panics

Panics in Go, by default, output a stacktrace to the standard output, providing valuable debugging information. However, recovering from a panic using recover() only returns an error description.

Is there a way to retrieve and store the stacktrace produced during a panic, making it easier to identify the exact location of the issue?

Using the runtime/debug Package

The answer lies in the runtime/debug package. This package provides a mechanism to access and store the stacktrace associated with a panic. Here's how:

package main

import (
    "fmt"
    "runtime/debug"
)

func main() {
    defer func() {
        if r := recover(); r != nil {
            fmt.Println("Panic detected:", r)
            stacktrace := debug.Stack()
            fmt.Println("Stacktrace:", string(stacktrace))
        }
    }()

    // Trigger a panic
    var mySlice []int
    j := mySlice[0] // Index out of bounds panic

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

This code defines a deferred function that handles any panics. When a panic occurs, the recover() function captures the error. Additionally, the debug.Stack() function is used to retrieve the stacktrace associated with the panic and store it as a string variable. Finally, both the error and the stacktrace are printed to the console for debugging purposes.

Running this code will output the following:

Panic detected: runtime error: index out of range
Stacktrace:
goroutine 1 [running]:
main.main.func1()
    /tmp/sandbox773777618/main.go:11 +0x60
panic(0xf9e00, 0x2078e0)
    /usr/local/go/src/runtime/panic.go:502 +0x2c0
main.main()
    /tmp/sandbox773777618/main.go:17 +0x60

In this output, the stacktrace clearly shows the line in the code that caused the panic, providing more valuable debugging information than just the error description.

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