DNS resolution fails after resolv.conf update

[Stanislav Baiduzhyi]

Hi Christos,

On Monday 04 May 2015 21:16:40 Christos Zoulas wrote:
> I don't think it is the job of the JDK to handle this. For example
> many systems (like NetBSD for example) work just fine without
> needing this, because their libc keeps track of resolv.conf changes.

Normally I would agree with you, but if the OS does not provide that 
functionality for any reason we still have to provide working solution from 
java perspective.

> On other systems, calling res_init() does not even work properly
> because the getaddrinfo() call uses the re-entrant API to be thread
> safe (res_ninit()/res_nsend() etc.).
> 
> Additionally res_init() isn't even thread-safe (on most implementations),
> so multiple threads calling it at the same time can corrupt the
> resolver state.
> 
> Fixing it the way you propose means that every application that
> does hostname/address resolution would need to be modified in order
> to work.

Good point. I see that some patches to glibc to handle this issue are using 
lock mechanism, plus Bernd suggested to use a separate thread for this. I'll 
try implementing both of those variants and will return with another webrev.

-- 
Regards,
    Stas