--- loncom/lonmaxima	2007/11/09 18:47:01	1.34
+++ loncom/lonmaxima	2007/11/09 18:51:10	1.35
@@ -3,7 +3,7 @@
 # The LearningOnline Network with CAPA
 # Connect to MAXIMA CAS
 #
-# $Id: lonmaxima,v 1.34 2007/11/09 18:47:01 albertel Exp $
+# $Id: lonmaxima,v 1.35 2007/11/09 18:51:10 albertel Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -44,6 +44,7 @@ use strict;
 # global variables
 my $PREFORK                = 5;        # number of children to maintain
 my $MAX_CLIENTS_PER_CHILD  = 50;       # number of clients each child should process
+my $extra_children         = 0;
 my %children               = ();       # keys are current child process IDs
 my $children               = 0;        # current number of children
 my $status;                            # string for current status
@@ -60,8 +61,13 @@ sub REAPER {                        # ta
                                     # and MAXIMA processes
     $SIG{CHLD} = \&REAPER;
     my $pid = wait;
-    $children--;
-    delete($children{$pid});
+    if (exists($children{$pid})) {
+	$children--;
+	delete($children{$pid});
+	if ($extra_children) {
+	    $extra_children--;
+	}
+    }    
 }
  
 sub HUNTSMAN {                      # signal handler for SIGINT
@@ -126,6 +132,10 @@ sub catchexception {
 }
 
 
+sub child_announce_death {
+    $SIG{USR1} = \&child_announce_death;
+    $extra_children++;
+}
 
 # ---------------------------------------------------------------- Main program
 # -------------------------------- Set signal handlers to record abnormal exits
@@ -133,6 +143,7 @@ sub catchexception {
  
 $SIG{'QUIT'}=\&catchexception;
 $SIG{__DIE__}=\&catchexception;
+$SIG{USR1} = \&child_announce_death;
  
 # ---------------------------------- Read loncapa_apache.conf and loncapa.conf
 &status("Read loncapa.conf and loncapa_apache.conf");
@@ -212,7 +223,7 @@ for (1 .. $PREFORK) {
 while (1) {
     &status('Parent process, sleeping');
     sleep;                          # wait for a signal (i.e., child's death)
-    for (my $i = $children; $i < $PREFORK; $i++) {
+    for (my $i = $children; $i < $PREFORK+$extra_children; $i++) {
         &status('Parent process, starting child');
         &make_new_child($server);           # top up the child pool
     }
@@ -238,6 +249,7 @@ sub make_new_child {
     } else {
         # Child can *not* return from this subroutine.
         
+	my $ppid = getppid();
      
         # unblock signals
         sigprocmask(SIG_UNBLOCK, $sigset)
@@ -274,6 +286,7 @@ sub make_new_child {
                     last;
                 } elsif ($reply=~/^Error\:/) {
                     &logthis('Died through '.$reply);
+		    kill('USR1' => $ppid);
                     $client->close();
                     $command->hard_close();     
                     exit;
@@ -283,6 +296,7 @@ sub make_new_child {
             }
         }
 
+	kill('USR1' => $ppid);
 	print $command ("quit();\n");
         # tidy up gracefully and finish