[sheepdog] [PATCH] logger: avoid using SIGHUP for detecting death of sheep

[Hitoshi Mitake]

At Wed, 15 Jan 2014 16:49:23 +0900,
Hitoshi Mitake wrote:
> 
> At Wed, 15 Jan 2014 11:13:50 +0800,
> Liu Yuan wrote:
> > 
> > On Tue, Jan 14, 2014 at 05:46:26PM +0900, Hitoshi Mitake wrote:
> > > It seems that current method of detecting sheep's death from logger
> > > process sometimes fails. The SIGHUP is caught as a request of log
> > > rotation.
> > > 
> > > The problem comes from that SIGHUP is used for both of log rotation
> > > request and death detection, and getppid() somestimes returns value
> > > not equal to 1 when SIGHUP which is caused by the death rises.
> > 
> > why not == 1 if sheep dies? I think we need to find the root cause instead of
> > a workaround.
> 
> I don't know why. It would be a timing problem. So I employed a
> certainly usable way.

The behavior of getppid() in the above case would be out of scope of
POSIX standard. At least I couldn't find any information about
them. So I think we should employ a certain way.

Thanks,
Hitoshi