Index: openacs-4/packages/acs-lang/tcl/lang-util-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-lang/tcl/lang-util-procs.tcl,v
diff -u -N -r1.54.2.3 -r1.54.2.4
--- openacs-4/packages/acs-lang/tcl/lang-util-procs.tcl	1 Jul 2019 16:55:43 -0000	1.54.2.3
+++ openacs-4/packages/acs-lang/tcl/lang-util-procs.tcl	18 May 2020 21:13:20 -0000	1.54.2.4
@@ -368,10 +368,9 @@
     @param locale  Name of a locale, as language_COUNTRY using ISO 639 and ISO 3166
     @return        IANA MIME character set name
 } {
-    # DRB: cache this now that ad_conn tracks it
-    set key ::lang::util::charset_for_locale($locale)
-    if {[info exists $key]} {return [set $key]}
-    set $key [db_string -cache_key ad_lang_mime_charset_$locale charset_for_locale {}]
+    return [acs::per_thread_cache eval -key acs-lang:charset_for_locale($locale) {
+        db_string -cache_key ad_lang_mime_charset_$locale charset_for_locale {}
+    }]
 }
 
 ad_proc -private lang::util::default_locale_from_lang_not_cached {