Index: openacs-4/packages/acs-tcl/tcl/cluster-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-tcl/tcl/cluster-procs.tcl,v
diff -u -r1.1.2.16 -r1.1.2.17
--- openacs-4/packages/acs-tcl/tcl/cluster-procs.tcl	11 Jul 2024 05:19:05 -0000	1.1.2.16
+++ openacs-4/packages/acs-tcl/tcl/cluster-procs.tcl	8 Aug 2024 14:30:53 -0000	1.1.2.17
@@ -103,8 +103,9 @@
             acs::cache_flush_all ""
             acs::cache_flush_pattern ""
             lang::message::cache ""
+            ad_parameter_cache_flush_dict ""
             ::acs::cluster "^::acs::cluster\s+join_request"
-            ::acs::cluster "^::acs::cluster\s+disconnect_request"            
+            ::acs::cluster "^::acs::cluster\s+disconnect_request"
         }
 
         #
@@ -276,7 +277,7 @@
                                     set ok 1
                                     break
                                 }
-                            }                            
+                            }
                         }
                     }
                 } else {
@@ -576,7 +577,7 @@
             # entities, we have to map container-internal IP addresses
             # to external accessible addresses.
             #
-            ns_log notice "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX NO USED !!!!!!!!!!!!!!!"
+            ns_log notice "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX NOT USED !!!!!!!!!!!!!!!"
             set containerMapping [::acs::container mapping]
             if {$containerMapping ne ""} {
                 set d [ns_parseurl $qualified_location]
@@ -651,7 +652,7 @@
                 #
                 dict set d host [ns_addrbyhost [dict get $d host]]
             }
-            
+
             set d [:map_inaddr_any -dict $d]
             dict with d {
                 set result [util::join_location -noabbrev -proto $proto -hostname $host -port $port]
Index: openacs-4/packages/acs-tcl/tcl/defs-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-tcl/tcl/defs-procs.tcl,v
diff -u -r1.81.2.29 -r1.81.2.30
--- openacs-4/packages/acs-tcl/tcl/defs-procs.tcl	6 Aug 2024 17:25:04 -0000	1.81.2.29
+++ openacs-4/packages/acs-tcl/tcl/defs-procs.tcl	8 Aug 2024 14:30:53 -0000	1.81.2.30
@@ -523,6 +523,33 @@
         nsv_set ad_param . .
     }
 
+    ad_proc -private ad_parameter_cache_flush_dict {
+        key
+        parmeter_name
+    } {
+        Flush a single value from the nsv cache.
+
+        This proc is necessary in cases, where a node writes a new
+        parameter value before it has read the old one.
+
+        Since a plain "nsv_dict unset ad_param $key $parameter_name"
+        raises an exception, when the pair does not exist, and we do
+        not want to allow in cluster requests arbitrary "catch"
+        commands, we allow "ad_parameter_cache_flush_dict" instead.
+        Probably, the best solution is to add support for
+
+            nsv_dict unset -nocomplain -- ad_param $key $parameter_nam
+
+        The existing nsv_dict was built after Tcl's "dict unset",
+        which does not have the "-nocomplain" option either. However,
+        an atomic operation would certainly be preferable over an exists/unset
+        pair, which is no acceptable solution.
+
+    } {
+        catch {nsv_dict unset ad_param $key $parameter_name}
+    }
+
+
     ad_proc -public ad_parameter_cache {
         -set
         -delete:boolean
@@ -542,9 +569,7 @@
 
     } {
         if {$delete_p} {
-            if {[nsv_dict exists ad_param $key $parameter_name]} {
-                ::acs::clusterwide nsv_dict unset ad_param $key $parameter_name
-            }
+            acs::clusterwide ad_parameter_cache_flush_dict $key $parameter_name
             acs::per_request_cache flush -pattern acs-tcl.ad_param-$key
             return
         }