debug=False (the default) hides debug output coming from the separate viewer process by capturing stderr with subprocess.PIPE, but (at least on some OSes) that pipe's buffer can fill after which the process hangs indefinitely. The hang is fixed by either setting debug=True or by using subprocess.DEVNULL instead of subprocess.PIPE to capture but ignore the output.
debug=False(the default) hides debug output coming from the separate viewer process by capturingstderrwithsubprocess.PIPE, but (at least on some OSes) that pipe's buffer can fill after which the process hangs indefinitely. The hang is fixed by either settingdebug=Trueor by usingsubprocess.DEVNULLinstead ofsubprocess.PIPEto capture but ignore the output.https://github.com/heremaps/pptk/blob/master/pptk/viewer/viewer.py#L56 is the offending line.