Index: openacs-4/packages/acs-tcl/tcl/apm-init.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-tcl/tcl/apm-init.tcl,v
diff -u -r1.3.2.1 -r1.3.2.2
--- openacs-4/packages/acs-tcl/tcl/apm-init.tcl	2 Sep 2021 17:10:27 -0000	1.3.2.1
+++ openacs-4/packages/acs-tcl/tcl/apm-init.tcl	2 Sep 2021 18:35:54 -0000	1.3.2.2
@@ -12,18 +12,6 @@
 nsv_array set apm_package_info [list]
 nsv_set apm_properties reload_level 0
 
-namespace eval apm {
-
-    # Cache the singleton_p property of all packages.
-    db_foreach get_singleton {
-        select package_key, singleton_p
-        from apm_package_types
-    } {
-        set ::apm::package_singleton_p($package_key) $singleton_p
-    }
-
-}
-
 # Local variables:
 #    mode: tcl
 #    tcl-indent-level: 4
Index: openacs-4/packages/acs-tcl/tcl/apm-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-tcl/tcl/apm-procs.tcl,v
diff -u -r1.114.2.33 -r1.114.2.34
--- openacs-4/packages/acs-tcl/tcl/apm-procs.tcl	2 Sep 2021 17:10:27 -0000	1.114.2.33
+++ openacs-4/packages/acs-tcl/tcl/apm-procs.tcl	2 Sep 2021 18:35:54 -0000	1.114.2.34
@@ -362,16 +362,12 @@
 } {
     @return boolean telling whether a package is a singleton or not
 } {
-    if {[info exists ::apm::package_singleton_p($package_key)]} {
-        return $::apm::package_singleton_p($package_key)
-    } else {
-        # Fallback for code executed when the cache has not been
-        # populated, or for new packages before restart.
-        return [db_string check_singleton {
+    return [acs::per_thread_cache eval -key acs-tcl.apm-singleton-$package_key {
+        db_string check_singleton {
             select singleton_p from apm_package_types
             where package_key = :package_key
-        } -default f]
-    }
+        } -default f
+    }]
 }
 
 ad_proc -public apm_version_loaded_p { version_id } {