Strange, intermittent panic issues

[brik...@gmail.com]

Hi folks,

We're using Go to write an open source CLI tool called terragrunt. We cross-compile binaries for the tool for multiple OS's. Some of the users are reporting intermittent crashes due to mysterious panic errors. Here are two examples:

• https://github.com/gruntwork-io/terragrunt/issues/41 (crash log) 
  
• https://github.com/gruntwork-io/terragrunt/issues/68 (crash log)
  

The panics seem to happen in strange places. For example, one happens deep in a call to the Printf method of a logger. Another in malloc.

We're at a loss for how to debug these as this doesn't seem to be caused by the usual culprits (e.g. a nil in the code) and can only be reproduced intermittently. Any suggestions?

Thanks,

Jim

[Tamás Gulácsi]

Compile with -race flag, and run that binary, and "go test -race", to eliminate the most possible reason: data race.

[r...@golang.org]

0xb01dfacedebac1e is a poison pill that usually indicates misuse of unsafe.Pointer.

If there is any use of unsafe.Pointer or CGO in the program that would be a good

place to start looking.

You can google "0xb01dfacedebac1e" for more details.

[brik...@gmail.com]

0xb01dfacedebac1e is a poison pill that usually indicates misuse of unsafe.Pointer. If there is any use of unsafe.Pointer or CGO in the program that would be a good place to start looking.

Interesting. As far as I know, we don't use unsafe.Pointer or cgo anywhere in the code, but I'll poke around. Maybe some dependency of ours does. 

Also, The particular line of code that leads to one of the panics is deep inside Go logger Printf code, so I'm not sure how anything in my code could lead to that?

Thanks,

Jim

[Dave Cheney]

On Wednesday, 7 December 2016 12:52:17 UTC+9, brik...@gmail.com wrote:

0xb01dfacedebac1e is a poison pill that usually indicates misuse of unsafe.Pointer. If there is any use of unsafe.Pointer or CGO in the program that would be a good place to start looking.

Interesting. As far as I know, we don't use unsafe.Pointer or cgo anywhere in the code, but I'll poke around. Maybe some dependency of ours does. 

Also, The particular line of code that leads to one of the panics is deep inside Go logger Printf code, so I'm not sure how anything in my code could lead to that?

The memory corruption probably happened before that line. If there is a data race in the program, then all bets are off.

[brik...@gmail.com]

Ah, I gotcha. OK, off I go to dig for unsafe.Pointer and cgo usages in a dependency :)

Thanks!

Jim