[sheepdog] [PATCH] lib/logger: nonblocking waitpid to avoid sheep process cannot exit

[Hitoshi Mitake]

At Wed, 11 Jun 2014 11:05:53 +0900,
Hitoshi Mitake wrote:
> 
> At Tue, 10 Jun 2014 18:22:11 +0800,
> Ruoyu wrote:
> > 
> > Sometimes sheep process cannot exit as we expected. I think the
> > problem might be waitpid, the system call waiting for process to
> > change state.
> > 
> > Current log_close function calling waitpid as a void method. It is
> > better to retrieve the return value and pass the nonblocking flag,
> > that is WNOHANG, to it.
> > 
> > Signed-off-by: Ruoyu <liangry at ucweb.com>
> > ---
> >  lib/logger.c | 24 ++++++++++++++++++------
> >  1 file changed, 18 insertions(+), 6 deletions(-)
> > 
> > diff --git a/lib/logger.c b/lib/logger.c
> > index 6829f45..79c60a7 100644
> > --- a/lib/logger.c
> > +++ b/lib/logger.c
> > @@ -711,13 +711,25 @@ int log_init(const char *program_name, enum log_dst_type type, int level,
> >  
> >  void log_close(void)
> >  {
> > -	if (la) {
> > -		la->active = false;
> > -		waitpid(logger_pid, NULL, 0);
> > +	if (!la)
> > +		return;
> >  
> > -		syslog(LOG_WARNING, "logger pid %d stopped\n", logger_pid);
> > -		closelog();
> > -		free_logarea();
> > +	while (true) {
> > +		la->active = false;

Seems that the above assignment statement can be placed before the loop.

Thanks,
Hitoshi

> > +		pid_t pid = waitpid(logger_pid, NULL, WNOHANG);
> 
> Interleaved statement and declaration is not allowed in the current
> coding style of sheepdog.
> # Personally I really like it but it is denied in the past.
> 
> Other part looks good and quite reasonable to me.
> 
> Thanks,
> Hitoshi
> 
> > +		if (pid == 0) {
> > +			usleep(100000);
> > +			continue;
> > +		} else if (pid > 0) {
> > +			syslog(LOG_WARNING, "logger pid %d stopped\n",
> > +					logger_pid);
> > +			closelog();
> > +			free_logarea();
> > +			break;
> > +		} else {
> > +			syslog(LOG_ERR, "waitpid() failure\n");
> > +			exit(1);
> > +		}
> >  	}
> >  }
> >  
> > -- 
> > 1.8.3.2
> > 
> > 
> > -- 
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