Francesco P Lovergine 
#Perl multi-threaded script. Do suggestions about how to debug such type of issues? Maybe in the main thread? Of course that does not happen always.
Toshiro N.@gisgeek Yes, don't do multithreading in perl.
@cpnt eh, that is the final solution, a bit too drastic. Consider that this happens only during a specific pipeline, the whole beast works like a charm 😀