Re: ldirectord fork a new daemon?

On Thu, Sep 08, 2005 at 02:27:53AM +0000, Eric Chan wrote:
> Horms <horms <at> verge.net.au> writes:
> 
> > > Dear Horms,
> > > 
> > > Thanks for your reply.I have carried out another test using a simple perl 
> > > script as below
> > > 
> > > #!/usr/bin/perl
> > > while(1){
> > >  system("rsh pct62 /tmp/alivetcp");
> > >  sleep 1;
> > > }
> > > 
> > > There is no time wait problem. It seems that the problem is not related to 
> the 
> > > rsh.
> > > 
> > > I have put the above perl script within the ldirectord perl script as below 
> and 
> > > the time wait problem occur.
> > > 
> > > 
> > > if ($opt_h) {
> > > 	&system_wrapper("/usr/bin/perldoc -U $LDIRECTORD");
> > > } else {
> > > 	# There is a memory leak in perl's socket code when
> > > 	# the default IO layer is used. So use "perlio" unless
> > > 	# something else has been explicitly set.
> > > 	# http://archive.develooper.com/perl5-porters <at> 
> perl.org/msg85468.html
> > > 	unless(defined($ENV{'PERLIO'})) {
> > > 		$ENV{'PERLIO'} = "perlio";
> > > 		exec_wrapper($0,  <at> OLD_ARGV);
> > > 	}
> > > 
> > > 	$initializing = 1;
> > > 	ld_init();
> > > 	ld_setup();
> > > 	ld_start();
> > > 	ld_cmd_children("start", %LD_INSTANCE);
> > > 	$initializing = 0;
> > > 	#ld_main();
> > >         while(1){
> > >            system("rsh pct62 /tmp/alivetcp");
> > >            sleep 1;
> > >         }
> > > }
> > > 
> > > 
> > > However, once I have comment the call to the &ld_daemon() within ld_init(), 
> the 
> > > problem disappear.
> > 
> > I suspect the problem is that rsh expects a terminal,
> > however once &ld_daemon() has been called, there isn't one.
> > 
> > If you run ldirectord with the supervised directive in
> > the ldirectord.cf file, then it will not call &ld_daemon(),
> > it will not detatch from the terminal, and you should
> > be able to run rsh. 
> > 
> > Internally, your code could check for $SUPERVISED == 1,
> > and if this is not true then flag an error that the rsh
> > check will not work.
> > 
> > However, a better solution would be to have an implementation
> > of the rsh protocol that did not require a terminal. Perhaps
> > there is one on CPAN. If not, it should be easy enough to create.
> > 
> 
> Dear Horms,
> 
> Thx for your reply. After viewing your advice, I go to have a detail look of 
> the rsh from the man page and discover that there is a bug with rsh. I have 
> copy that part as below
> 
> BUGS
>        If  you  are  using  csh(1)  and put a rsh(1) in the background without
>        redirecting its input away from the terminal, it will block even if  no
>        reads  are  posted  by  the remote command.  If no input is desired you
>        should redirect the input of rsh to /dev/null using the -n option.
> 
> After adding the -n attribute, the time_wait disappear. 

Excellent, I am glad to hear that it is working.

-- 
Horms


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