Comment by Eric Lindblad 23-02-2016 http://www.nurmi-labs.blogspot.com cf: http://comments.gmane.org/gmane.comp.search.xapian.general/9948 I would suspect the fork here, if there are any threads involved. What Tcl really needs is some pthread_atfork() triggers, but they aren?t exposed in any meaningful way, so you can lose things over a fork split.