On Thu, Nov 10, 2016 at 3:18 AM, <iakov.davy...@gmail.com> wrote:
>
> I don't have a minimal example yet, but this looks very suspicious. It seems
> that sometimes defer called before the function finishes, if cgo code with
> callbacks is called in it.
>
> Here's the code:
>
> func (n *NLOPT) Run(iterations int) {
> log.Debug("entering Run method")
> ...
> nID := registerObject(n)
> defer unregisterObject(nID)
> ...
> // this will call some go function
> n.optRes = C.nlopt_optimize(n.gopt,
> (*C.double)(unsafe.Pointer(&x[0])), &maxf)
> ....
> log.Debug("leaving Run method")
> }
>
>
> Here's what I see in my logs:
>
> entering Run method
> register: 1 (0xc82000a900)
> ... other messages, no "leaving Run method" ...
> unregister: 1 (0xc82000a900)
> panic: interface conversion: interface {} is nil, not *optimize.NLOPT
> (this panic happens because something was prematurely unregistered)
>
> So defer is executed before the method exits.
>
> I tried this in go v1.5 and v1.7, linux64. Sometimes it happens not
> immediately, but after some time.
>
> Are there any special defer rules regarding cgo & callbacks which I do not
> know?
I doubt it. Please show us a minimal example.
Ian
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