The Mate DM file manager (caja) triggers randomly tons of per seconds warnings/alerts in autohome.

[fpl]

This is an issue that causes a sucking load of CPU and the filling of tons of GBs for logging. It stops after restarting caja processes.

...
Dec 29 11:04:02 xxxxx autodir[1396]: [autohome] warning: no user found with name .hidden
Dec 29 11:04:03 xxxxx autodir[1396]: [autohome] alert: module autohome failed on .hidden
Dec 29 11:04:12 xxxxx autodir[1396]: [autohome] warning: no user found with name .hidden
Dec 29 11:04:12 xxxxx autodir[1396]: [autohome] alert: module autohome failed on .hidden
Dec 29 11:04:12 xxxxx autodir[1396]: [autohome] warning: no user found with name .hidden
Dec 29 11:04:12 xxxxx autodir[1396]: [autohome] alert: module autohome failed on .hidden
Dec 29 11:04:12 xxxxx autodir[1396]: [autohome] warning: no user found with name .hidden
Dec 29 11:04:12 xxxxx autodir[1396]: [autohome] alert: module autohome failed on .hidden
Dec 29 11:04:12 xxxxx autodir[1396]: [autohome] warning: no user found with name .hidden
Dec 29 11:04:12 xxxxx autodir[1396]: [autohome] alert: module autohome failed on .hidden
Dec 29 11:04:12 xxxxx autodir[1396]: [autohome] warning: no user found with name .hidden
Dec 29 11:04:12 xxxxx autodir[1396]: [autohome] alert: module autohome failed on .hidden
...

apparently, this is Mate-specific. The pattern name changes and often assumes the aspect of <some>.png, <some>.ico and other graphics filenames (where typically 'some' is a username).

[fpl]

I finally found the workflow that causes this problem. The context is a long time use for MATE within a VNC session. If mate-screensaver is allowed to run (default) it triggers caja as pointed. Of course a reasonable workaround is disabling the screensaver activation (which is reasonable in a VNC session).