Syscalls inside loops + runtime.KeepAlive

[Caleb Spare]

I have a question about this runtime.KeepAlive call:

https://github.com/golang/go/blob/041ecb697f0e867a2bb0bf219cc2fd5f77057c2e/src/os/dir_unix.go#L68

(There are other examples in the stdlib as well, I think.)

It seems to me that, strictly speaking, KeepAlive is unnecessary here
since the compiler/runtime cannot know whether the loop will terminate
before the result of the ReadDirent is seen. Is that true?

I'm not arguing that the KeepAlive should be removed; it's probably
best to stick with the pattern syscall(f.Fd(), ...);
runtime.KeepAlive(f) in most cases. I'm just checking my understanding
here.

Thanks!
Caleb

[Ian Lance Taylor]

Yes, I think you are correct.

Ian

[Caleb Spare]

Thanks, Ian.