@Jim007 has reported an Atril-related DOS in the following thread:
So far, no one was able to reproduce his report.
One of the MATE devs has indicated a workaround to neutralize atril-thumbnailer in a comment:
You can also turn off preview of files in caja preferences (caja is the file browser):
In "Extensions" uncheck "atril properties"
In "Preview" set everything to "Never"