Remove first four calls of stacktrace

[bufdev]

When you get a stacktrace, it will always return:

go.uber.org/zap.takeStacktrace(0xc42005d000, 0x400, 0x400, 0x0, 0x0, 0xc4200f9901)
	/Users/peteredge/gocode/src/go.uber.org/zap/stacktrace.go:33 +0x64
go.uber.org/zap.Stack(0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0)
	/Users/peteredge/gocode/src/go.uber.org/zap/field.go:197 +0x7a
go.uber.org/zap.(*Logger).check(0xc420072300, 0x1, 0x12969d2, 0x4, 0xc4200784c0)
	/Users/peteredge/gocode/src/go.uber.org/zap/logger.go:254 +0x212
go.uber.org/zap.(*Logger).Warn(0xc420072300, 0x12969d2, 0x4, 0xc4200784c0, 0x1, 0x1)
	/Users/peteredge/gocode/src/go.uber.org/zap/logger.go:154 +0x44

This doesn't have much use to the user, so we should try to remove these. This might be a little tricky, I'll look into it at some point.

[enjoylife]

@akshayjshah I'm not sure if this is a regression or the intended behavior, but I'm still seeing a large number of frames being returned.

Heres an example call to zap.S().Error from some application code of mine.

2017-05-02T22:03:11.186-0700	ERROR	config/postgres.go:32	Unable to connect to postgres database{error 25 0  dial tcp [::1]:5432: getsockopt: connection refused} {config 2 0  postgresql://gecko_admin:devpass@localhost:%!d(string=5433)}	{"app_name": "ProjectGecko", "version": "0.1.0"}
go.uber.org/zap.Stack
	/Users/matt/Programming/GoDevel/src/go.uber.org/zap/field.go:209
go.uber.org/zap.(*Logger).check
	/Users/matt/Programming/GoDevel/src/go.uber.org/zap/logger.go:273
go.uber.org/zap.(*Logger).Check
	/Users/matt/Programming/GoDevel/src/go.uber.org/zap/logger.go:146
go.uber.org/zap.(*SugaredLogger).log
	/Users/matt/Programming/GoDevel/src/go.uber.org/zap/sugar.go:223
go.uber.org/zap.(*SugaredLogger).Error
	/Users/matt/Programming/GoDevel/src/go.uber.org/zap/sugar.go:102
gecko/config.SetupPostgres
	/Users/matt/Programming/ProjectGecko/src/api/src/gecko/config/postgres.go:32
main.main
	/Users/matt/Programming/ProjectGecko/src/api/server.go:40

My assumption is that those zap specific lines are supposed filtered out. Is that your assumption too, @peter-edge ?

Taking a quick peek at the zap code, I see in stacktrace.go the array called _stacktraceIgnorePrefixes which holds the list of prefixes that get filtered.

My current quick fix is just to add "go.uber.org/zap" to this list which removes the noise from my logs.

I took a look at #311 and the test cases but I can't tell what the intended behavior exactly is.
I have a feeling my quick fix probably filters out too much for other applications and for uber, but it works for my small use case.

[Till--H]

Any update on this one? My logs are also full of stack frames from within zap. It would be great if they're filtered out.

[prashantv]

The original issue was to filter out runtime stacks, and the very last zap stacktraces. I've filed a separate issue #488 to discuss whether all zap stack frames should be removed.