--- loncom/lonnet/perl/lonnet.pm	2004/09/27 19:00:16	1.548
+++ loncom/lonnet/perl/lonnet.pm	2004/10/06 09:48:39	1.550
@@ -1,7 +1,7 @@
 # The LearningOnline Network
 # TCP networking package
 #
-# $Id: lonnet.pm,v 1.548 2004/09/27 19:00:16 albertel Exp $
+# $Id: lonnet.pm,v 1.550 2004/10/06 09:48:39 foxr Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -52,6 +52,7 @@ use Apache::lonlocal;
 use Storable qw(lock_store lock_nstore lock_retrieve freeze thaw);
 use Time::HiRes qw( gettimeofday tv_interval );
 my $readit;
+my $max_connection_retries = 10;     # Or some such value.
 
 =pod
 
@@ -116,14 +117,40 @@ sub logperm {
 sub subreply {
     my ($cmd,$server)=@_;
     my $peerfile="$perlvar{'lonSockDir'}/$server";
-    my $client=IO::Socket::UNIX->new(Peer    =>"$peerfile",
-                                     Type    => SOCK_STREAM,
-                                     Timeout => 10)
-       or return "con_lost";
-    print $client "$cmd\n";
-    my $answer=<$client>;
-    if (!$answer) { $answer="con_lost"; }
-    chomp($answer);
+    #
+    #  With loncnew process trimming, there's a timing hole between lonc server
+    #  process exit and the master server picking up the listen on the AF_UNIX
+    #  socket.  In that time interval, a lock file will exist:
+
+    my $lockfile=$peerfile.".lock";
+    while (-e $lockfile) {	# Need to wait for the lockfile to disappear.
+	sleep(1);
+    }
+    # At this point, either a loncnew parent is listening or an old lonc
+    # or loncnew child is listening so we can connect or everything's dead.
+    #
+    #   We'll give the connection a few tries before abandoning it.  If
+    #   connection is not possible, we'll con_lost back to the client.
+    #   
+    my $client;
+    for (my $retries = 0; $retries < $max_connection_retries; $retries++) {
+	$client=IO::Socket::UNIX->new(Peer    =>"$peerfile",
+				      Type    => SOCK_STREAM,
+				      Timeout => 10);
+	if($client) {
+	    last;		# Connected!
+	}
+	sleep(1);		# Try again later if failed connection.
+    }
+    my $answer;
+    if ($client) {
+	print $client "$cmd\n";
+	$answer=<$client>;
+	if (!$answer) { $answer="con_lost"; }
+	chomp($answer);
+    } else {
+	$answer = 'con_lost';	# Failed connection.
+    }
     return $answer;
 }