@Danilo the ticket for the async issue is already here: https://sft.its.cern.ch/jira/browse/ROOT-9277
@couet I run ROOT in batch mode (root -b), I invoke a function, which creates TCanvas object on stack. Then it draws some histograms and calls TCanvas::Print. I will recheck, but it seems that I got segfaults just because I’ve tried to run this functions inside async, with implicit MT with more than 1 thread enabled.