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From Dirk Lutzebaeck <lut...@aeccom.com>
Subject Re: How to restart the root server from within modperl?
Date Wed, 13 Aug 2003 15:48:19 GMT

Thanks, I made it a bit more simple:

  use POSIX;

  if (! fork) { # child
     setsid;
     POSIX::close(0);
     POSIX::close(1);
     exec("restart-apache-command");
  }

Works great!

Thanks,

Dirk




Torsten Foertsch writes:
 > -----BEGIN PGP SIGNED MESSAGE-----
 > Hash: SHA1
 > 
 > On Tuesday 12 August 2003 11:50, Dirk Lutzebaeck wrote:
 > > Dennis Stout writes:
 > >  > On a whim, I would try writing a second script to do the actual shutdown
 > >  > and restart of Apache.
 > >  >
 > >  > Then have your mod_perl program either run it in the background (with a
 > >  > &) or fork it into another process.
 > >
 > > Did exactly that but is has the effect that when the parent (root)
 > > apache is killed it kills all children including the script itself. So
 > > the server wont start again.
 > 
 > I have done something like this several times. My code (it works since 1998 on 
 > a highly used WEB Server with perl5.005_3) looks like that:
 > 
 > ...
 > 
 > sub sysclose {
 >   require 'syscall.ph';
 >   syscall &SYS_close, shift()+0;
 > }
 > 
 > sub RLIMIT_NOFILE {7;}		# this is for LINUX
 > sub getrlimit {
 >   require 'syscall.ph';
 >   my $x="x"x8;			# result
 >   syscall &SYS_getrlimit, shift()+0, $x;
 >   unpack "ii", $x;
 > }
 > 
 > sub close_fd {
 >   my @l=getrlimit( RLIMIT_NOFILE );
 >   my $l;
 > 
 >   for( $l=0; $l<$l[0]; $l++ ) {
 >     next if( $l==2 );		# close all file descriptors except of STDERR
 >     sysclose $l;
 >   }
 > }
 > 
 > sub disconnect_from_apache {
 >   use POSIX qw/setsid/;
 > 
 >   setsid;
 >   close_fd;
 > }
 > 
 > ...
 > 
 >     my $child=fork;
 >     unless( defined $child ) {
 >       ...
 >       return OK;
 >     }
 >     if( $child ) {
 >       my $child_status=0;
 >       if( waitpid( $child, 0 )==$child ) {
 > 	$child_status=$?;
 >       }
 > 
 >       if( $child_status==0 ) {
 >         ...
 > 	return OK;
 >       } else {
 > 	# The first fork succeeded but the second failed
 >         ...
 > 	return OK;
 >       }
 >     } else {
 >       # Child process: fork again to detach from parent process
 >       $child=fork;
 >       CORE::exit( 0 ) if( $child ); # parent exits
 >       unless( defined $child ) {
 >         ...
 > 	CORE::exit( 1 );
 >       }
 >       # Now we are the 2nd child process.
 >       $self->disconnect_from_apache;
 >       $self->doit( ... );                   # <== here comes the real code
 >       CORE::exit( 0 );
 >     }
 > 
 > ...
 > 
 > $self->doit() is called in a separate process group and is not killed by a 
 > signal sent to the apache process group. Further, all files save STDERR are 
 > closed. This is needed since the code runs under mod_perl and the long 
 > running child process inherits the open connection to the browser. If this 
 > connection is not closed the browser shows an endless spinning globe or 
 > something like that in the upper right corner.
 > 
 > Torsten
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 > 
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 > =xId6
 > -----END PGP SIGNATURE-----
 > 

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