toni@purkki:~$ valgrind --tool=massif fastgallery -i -o output input
==1904160== Massif, a heap profiler
==1904160== Copyright (C) 2003-2017, and GNU GPL'd, by Nicholas Nethercote
==1904160== Using Valgrind-3.16.1 and LibVEX; rerun with -h for copyright info
==1904160== Command: fastgallery -i -o tempgallery /home/toni/Dropbox/Pictures/Matti/Matin\ valokuvat/
==1904160== 
Creating gallery...
10 / 459 [--->______________________________________________________________________________________________________________________________________________] 2.18% 1 p/s==1904160== Can't extend stack to 0xfffffffffffff0b8 during signal delivery for thread 20:
==1904160==   too small or bad protection modes
==1904160== 
==1904160== Process terminating with default action of signal 11 (SIGSEGV)
==1904160==  Access not within mapped region at address 0xFFFFFFFFFFFFF0B8
==1904160==    at 0x38688BD9: ??? (in /run/user/1000/orcexec.mIQUuO (deleted))
==1904160==  If you believe this happened as a result of a stack
==1904160==  overflow in your program's main thread (unlikely but
==1904160==  possible), you can try to increase the size of the
==1904160==  main thread stack using the --main-stacksize= flag.
==1904160==  The main thread stack size used in this run was 8388608.
==1904160== 
==1904160== Process terminating with default action of signal 11 (SIGSEGV)
==1904160==  Access not within mapped region at address 0xFFFFFFFFFFFFFF78
==1904160==    at 0x4832130: _vgnU_freeres (in /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_core-amd64-linux.so)
==1904160==  If you believe this happened as a result of a stack
==1904160==  overflow in your program's main thread (unlikely but
==1904160==  possible), you can try to increase the size of the
==1904160==  main thread stack using the --main-stacksize= flag.
==1904160== 
Segmentation fault (core dumped)