Repository navigation
Wrap() duplicates call stack #242
Description
I am currently considering using pkg/errors.
However, I have a question, so I'm leaving a question.
I ran the example code and expected the output shown in the code comments.
However, if you look at the output attached below, you can see that the output is completely different. The problem is that duplicate stacks are displayed.
And this also happens when I wrap the error passed to New() and WithStack(). Is this the intended behavior?
Environment:
pkg/errors version: 0.9.1
Go version: 1.16
OS version: macOS Big Sur 11.0.1
My output:
error
main.fn
/Users/choedongcheol/Workspace/temp/test/main.go:100
main.ExampleWrap_extended
/Users/choedongcheol/Workspace/temp/test/main.go:116
main.main
/Users/choedongcheol/Workspace/temp/test/main.go:208
runtime.main
/Users/choedongcheol/.gvm/gos/go1.16/src/runtime/proc.go:225
runtime.goexit
/Users/choedongcheol/.gvm/gos/go1.16/src/runtime/asm_amd64.s:1371
inner
main.fn
/Users/choedongcheol/Workspace/temp/test/main.go:101
main.ExampleWrap_extended
/Users/choedongcheol/Workspace/temp/test/main.go:116
main.main
/Users/choedongcheol/Workspace/temp/test/main.go:208
runtime.main
/Users/choedongcheol/.gvm/gos/go1.16/src/runtime/proc.go:225
runtime.goexit
/Users/choedongcheol/.gvm/gos/go1.16/src/runtime/asm_amd64.s:1371
middle
main.fn
/Users/choedongcheol/Workspace/temp/test/main.go:102
main.ExampleWrap_extended
/Users/choedongcheol/Workspace/temp/test/main.go:116
main.main
/Users/choedongcheol/Workspace/temp/test/main.go:208
runtime.main
/Users/choedongcheol/.gvm/gos/go1.16/src/runtime/proc.go:225
runtime.goexit
/Users/choedongcheol/.gvm/gos/go1.16/src/runtime/asm_amd64.s:1371
outer
main.fn
/Users/choedongcheol/Workspace/temp/test/main.go:103
main.ExampleWrap_extended
/Users/choedongcheol/Workspace/temp/test/main.go:116
main.main
/Users/choedongcheol/Workspace/temp/test/main.go:208
runtime.main
/Users/choedongcheol/.gvm/gos/go1.16/src/runtime/proc.go:225
runtime.goexit
/Users/choedongcheol/.gvm/gos/go1.16/src/runtime/asm_amd64.s:1371
Activity
davecheney commentedon Jun 12, 2021
Yes, this is how it works. I couldn’t think of an algorithm to collapse related stack frames. I recommend not using WithStack at intermediary levels as it adds little value. WithStack was added because sometimes errors cross stack boudnaires, ie being lsssd through a channel to another goroutine.
puellanivis commentedon Jun 12, 2021
This is a well known caveat with
pkg/errors. You should try to ensure that at the earliest layer, all errors that are returned should be returned with a stack trace, and then each layer returning an error from a call into your own code usesWithMessage.As davecheney points out, it’s really hard to algorithmically figure out when and where a stack trace should be attached, while for humans it’s a comparatively simple matter of policy enforcement.
dc7303 commentedon Jun 15, 2021
@davecheney @puellanivis Thank you so much for your reply.
shubhamJay commentedon Aug 28, 2021
@davecheney @puellanivis , I understood
WithStackshouldn't be used at intermediary levels. But would like to understand your thoughts onWithStackfunction idempotent (by adding a condition to check if passed error is already awithStacktype), so there may not be need of complex algo to collapse stack frames ORWithStackmultiple times.Ps: I am very new to Golang, so please point out If I am missing out on something very obvious.
puellanivis commentedon Aug 29, 2021
We already have as rich of an error type as is feasible to represent an error with a stack. It is not really feasible that functions should return any error type other than
error. The ubiquity of theerrortype is an important part of ensuring ease of interoperability and consistency of code.It is not always the right thing to do to never allow adding a secondary stacktrace. In 99% of cases, it never makes sense, but especially if a piece of code has a significant amount of error handling, a second stacktrace might actually make sense.
shubhamJay commentedon Aug 30, 2021
Got it. Thank you @puellanivis.