[ic] Restart and stop problems (multilple processes)

[Daniel Hutchison]

> > FWIW, I did try to look into this issue a little more in depth. However,
> > I havn't had a whole lot of time. I havn't found anything definite yet,
> > just some suspicions.  
> > 
> > >From what I can tell, the problem seems to be in the locking of the pid
> > file.  Eg. interchange attempts to lock the pid file when it starts up. 
> > If it can't lock the pid file, it assumes another interchange process is
> > running.  What I suspect is that interchange locks the pid file before
> > it forks. Since on solaris, locks created with flock() aren't inherited
> > across forks.   As a result, when the parent process exits the pid file
> > becomes unlocked.  When interchange is then run with the shutdown
> > command it detects that the pid file unlocked and thinks that there
> > isn't a running interchange process.
> > 
> > What I have done is verify that the default install of interchange on my
> > solaris box uses the flock() function to lock the pid file.  I've also
> > created a mini perl program that just locks files based off the code in
> > interchange.  The file locking works fine until I throw a fork() in
> > it...
> > 
> > Anyway, I hope this helps a bit.  
> 
> Turns out the files lock fine, but LOCK_NB is not working, at least on the
> solaris server I tested on (thanks Dorothy). It doesn't work no matter the
> state of fork. In any case, grab_pid happens in the context of the last
> fork, as I thought.
> 
> I could add a -badlock option at the commandline, but it would seem
> to make sense to just fix Perl on the affected systems. 

Looks like we were both wrong...  I was able to track the problem down
to the read_pid() that was being called from the server_start_message()
in lib/Vend/Server.pm.  It appears that read_pid() is releasing the lock
when it opens and closes the pid file.

Anyway, here is a simple patch that fixes the problem on Solaris:

diff -rNu ../interchange-4.9.7-200301240658-orig/lib/Vend/Server.pm ./lib/Vend/Server.pm
--- ../interchange-4.9.7-200301240658-orig/lib/Vend/Server.pm   Fri Dec 13 07:11:35 2002
+++ ./lib/Vend/Server.pm        Thu Feb  6 10:40:21 2003
@@ -1200,7 +1200,7 @@
        push (@types, 'SOAP') if $Global::SOAP;
        push (@types, 'mod_perl') if $Global::mod_perl;
        my $server_type = join(" and ", @types);
-       my $pid = read_pidfile();
+       my $pid = $$;
        my @args = $reverse ? ($server_type, $pid) : ($pid, $server_type);
        return ::errmsg ($fmt , @args );
 }