getsentry / getsentry/sentry-go

Reporting Unrecovered Panics

Open
#968 3 comments 0 reactions 0 assignees View on GitHub
Errors Feature Go
Dominant language
Go
Stars
1.1k
Forks
262
Avg merge
1d 48m
Merged PRs (30d)
7

Description

### Problem Statement

The current SDK will not report a panic if it isn't caught in a recover. The following example does not report any errors to Sentry. Panics and unhandled crashes are arguably the highest value errors an SRE would want to monitor and alert on in a production environment.

By default, Go will print the panic trace to stderr before exiting, but there is no opportunity for another go routine to recover the panic before the process terminates (note the absence of "Main exiting" in the output below).

There are a whole host of reasons a go program could panic, from data races to nil pointer dereferences, and there does not seem to be a good way to enforce panic recovery in every single go routine a developer might add to the codebase.

```
package main

import (
"log"
"time"
"github.com/getsentry/sentry-go"
)

func main() {
// Initialize Sentry SDK
err := sentry.Init(sentry.ClientOptions{
Dsn: "https://your-dsn@sentry.io/your-project",
Debug: true,
})
if err != nil {
log.Fatalf("sentry.Init: %s", err)
}
defer sentry.Flush(2 * time.Second)

// Main goroutine recovery attempt (won't help)
defer func() {
if r := recover(); r != nil {
log.Println("Main recovered:", r)
}
}()

// Start problematic goroutine
go func() {
panic("goroutine panic - unrecovered")
}()

// Keep main alive to observe behavior
time.Sleep(1 * time.Second)
log.Println("Main exiting")
}
```

Ouputs:
```
...
[Sentry] 2025/02/20 16:41:01 Integration installed: GlobalTags
panic: goroutine panic - unrecovered

goroutine 24 [running]:
main.main.func2()
/Users/chodges/go-panic/panic.go:29 +0x2c
created by main.main in goroutine 1
/Users/chodges/go-panic/panic.go:28 +0xbc
```

### Solution Brainstorm

Triggering a core dump is one way to get around this problem and report the error to Sentry, however that has its own set of drawbacks:
- Exposes sensitive data
- Generates large files which could fill the disk
- High file I/O could compromise performance of the compute node

Another option would be to take a config option in the SDK initialization that has a file path to stderr output for the process. Then on SDK startup, it could go through the stderr output and look for panic stack traces and report them to Sentry. Parsing logs for errors is messy, but given how Golang handles unrecovered panics there is really nothing that can be done with error handling post-panic and before process termination.

Contributor guide

Open the contributing guide

Assessment

This issue has not been assessed yet.

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.