dr2chase/GolangBostonMeetup_2017_06_debugging.md

## GolangBostonMeetup_2017_06_debugging.md

      
    Raw
  

              GolangBostonMeetup_2017_06_debugging.md
            
          
    Here are my notes from the Golang Boston Meetup 2017-06-27 debugging meeting, such as they are.
Corrections/elaborations welcome.
Notes from debugging group.
TLDR: fmt.Println is still very common;
nobody in the room knew everything -- i.e., there's debugging tricks and techniques that you probably don't know;
there's ever so much "upside potential" in the current tools.
Techniques mentioned:

fmt.Println
logging
context.Context
crash dumps / core files
process snapshots
Delve (Go debugger developed by derekparker at CoreOS)
flame graphs for performance problems
counters (for when logging overheads are too high; Netflix uses these)
dtrace
goroutine visualizations ("Divan" is author ?)
Jetbrains Gogland (pre-release; based on Delve)
Visual Studio Go Extensions (VSCode? "good"; also based on Delve)
profligate git branching as a debugging tool (easy to recover what worked, look for changes that matter)
go test; write lots of tests, use them.
pprof
git bisect
runtime trace: https://godoc.org/runtime/trace
vtune

wish list:

a magic command line arg that would make channels "echo" (log of channel behavior)
"how did I get from here to there?" (single step is broken sometimes, and the tedious process could be automated)
"show references" (a reverse garbage collector, "why is this still live?")
logging, seems like nobody gets it right, we keep on writing our own.
a refactoring tool, "I need a context here in f, make it so".
"stack traces" should have an option to provide values of local variables, where possible.
goimports can be a pain if its default is a wrong guess and packages come and go during hacking; repeating the same wrong-guess correction is annoying.
when hacking towards a bug diagnosis/fix, would be nice to have forgive variable declared-not-used (it's friction).
want a tool (gui?) for exploring crash dumps (similar to above for stack traces)

random thoughts/suggestions:

an idiom-from-stackoverflow recognizer ("hey, we could train a neural net....")
git stash is dangerous
(to train better programmers) "Use examples that matter.  Just Say No to Fibonnacci." (real world, there's many new programmers for whom Fibonacci is a new thing, it's not as helpful as the math-is-fun crowd thinks)
what's the latest-greatest in vendoring? some people like "go dep", go vendor can be REALLY slow (150 kloc + 1.5Mloc vendored, 5 minutes)