FYI, this is quickly and easily reproducible, happens within seconds, and hits the same spot every time. Note-to-self (not for general consumption): my unit test to provoke this is to start the cogserver and run this shell script:
#!/bin/bash i=0 while true ; do let i=$i+1 if [ "$(($i % 2000))" -eq "0" ] ; then echo loop $i fi # echo '(display ctr)' | nc localhost 17001 echo '(NumberNode ctr)' | nc localhost 17001 done other testing variants are described in https://github.com/opencog/opencog/issues/2550