how do you permanently disable the screen saver in Xvfb?

Question

I tried disabling extension MIT-SCREEN-SAVER but the screensaver is activated after a little while anyway.

The list of loaded extensions is this

xdpyinfo -display :88|grep 'number of exte' -A 23
number of extensions:    23
    BIG-REQUESTS
    Composite
    DAMAGE
    DOUBLE-BUFFER
    DPMS
    DRI3
    GLX
    Generic Event Extension
    MIT-SHM
    Present
    RECORD
    RENDER
    SECURITY
    SGI-GLX
    SHAPE
    SYNC
    X-Resource
    XC-MISC
    XFIXES
    XInputExtension
    XKEYBOARD
    XTEST
    XVideo

Either fiberlamp or fuzzyflakes come to life at some point and consume a lot of CPU. I am trying to prevent unnecessary waste of CPU cycles for screen-savers.

EDIT on 2016-09-28: disabled extension DPMS, also wrote "mode: off" to file ~/.xscreensaver without any positive effect. The screensaver stubbornly gets activated after approximately 6 minutes (whatever the default is). The parent of the screensaver apps is "xscreensaver -no-splash" whose parent in turn is process 1 (init).

Answer 1

Uncontrollable screen saver is often due to the default configuration of X, which is most conveniently changed by editing or creating a new /etc/X11/xorg.conf. Use sudo nano /etc/X11/xorg.conf to edit the file. Add the following section:

Section "ServerFlags"
    Option "BlankTime" "0"
EndSection

For more information see the xorg.conf manual page

Answer 2

The connection between Xvfb and screensavers is tenuous. Screensavers are controlled by the X system, such as xfce, not by Xvfb. Xvfb is merely a screen to output pixels to, hence high CPU usage in screensaver apps and Xvfb must be disabled at the X(-org) level. You should set "*mode: off" in file /etc/X11/app-defaults/XScreenSaver and restart X or reboot.