Race condition in startup

[KnicKnic]

I found this while trying to embed gobetween and not run it standalone so it may not hit as easily in normal case, but the race is still there.

gobetween/main.go

Lines 83 to 89 in 7d8a736

	go api.Start((*cfg).Api)
	/* setup metrics */
	go metrics.Start((*cfg).Metrics)
	// Start manager
	go manager.Initialize(*cfg)

These calls all initialize defaults, however it is possible for the them not to complete before API calls get in. This then ends up in dereference of null.

I hit it in this case.

gobetween/src/manager/manager.go

Line 558 in 7d8a736

*server.MaxConnections = *defaults.MaxConnections

Ideally what main should do is run all of these synchronously to init them, and only then launch agents.

api.Initialize()
metrics.Initialize()
manager.Initialize()
go api.Start()
go metrics.Start()
go manager.Start()

[yyyar]

Could you please show the exact error message you got and steps to reproduce?

[KnicKnic]

.\test.exe  
panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xc0000005 code=0x0 addr=0x0 pc=0xa6c23e]

goroutine 1 [running]:
github.com/yyyar/gobetween/manager.prepareConfig(0xc129cb, 0x3, 0xc00018a048, 0x0, 0x0, 0x0, 0xc1961f, 0xd, 0xc12abe, 0x3, ...)
        C:/Users/nmaliwa/go/src/github.com/yyyar/gobetween/src/manager/manager.go:572 +0xbce
github.com/yyyar/gobetween/manager.Create(0xc129cb, 0x3, 0x0, 0x0, 0x0, 0x0, 0xc1961f, 0xd, 0xc12abe, 0x3, ...)
        C:/Users/nmaliwa/go/src/github.com/yyyar/gobetween/src/manager/manager.go:193 +0x218
main.main()
        C:/Users/nmaliwa/go/src/github.com/yyyar/gobetween/src/test/testapp.go:26 +0x1e4

so I effectively coppied your main.go into launch\launch.go
I then used the launch package to embed into a test app and add servers using the manager package.

see my repro commit
KnicKnic@d454094

[yyyar]

Thanks, I See. I suppose, for standalone gobetween, just reordering like this may be enough to fix a race condition:

 // Init metrics
metrics.Start((*cfg).Metrics)

// Init manager
manager.Initialize(*cfg)

// Start API
go api.Start((*cfg).Api)

[yyyar]

fixed by #261