Ann mentioned to have added a "package require Thread"... which is not the way to go. My guess is that she took the thread library, which is a the result of a off-the-shelf Tcl installation, and loaded this this way - leading to the broken behavior.
The problem here is, that libthread can be compiled as a tcl package or as a AOLserver/Naviserver module. The latter is required here. In order to compile libthread as AOLserver/NaviServer module, it has to be configured with "--with-naviserver=..." and then loaded as a module (see e.g. [1]).
But of course, the easiest approach is get it via install-ns [2], which does this for you. Maybe Ann has done this, and was brought to the wrong track by the 2-server config file, which was stripped down from the classical sample config files doing already the right thing.
i will update the wiki page concerning libthread....
all the best
-g
[1] https://bitbucket.org/naviserver/naviserver/src/70aaa5cfbd474b3b94a9a98e868f1e42e23861fd/openacs-config.tcl#lines-752
[2] https://openacs.org/xowiki/naviserver-openacs
