[Xquartz-dev] xquarz uses 100% of CPU when not focused

[Gene Selkov]

I started a bare xterm as suggested and worked for a couple hours with
the osx apps, occasionally using that xterm as well. Everything was
cool. Literally. The CPU temperature remained in the lower forties
(C), and the fan didn't come on even momentarily.

Then I started icewm and gimp, and spent about 10 minutes abusing the
latter. I know how to break it simply by drawing lines with a stylus.
But that's a different story, I just want to comment that breaking
gimp under icewm appeared to be somewhat more difficult that under
quartzwm. It tends to break when it draws a continuous line too
quickly and for too long -- to the point that the undo operation
doesn't completely erased the line; it only erases random rectangular
panels, leaving other panels unerased.

Then, after 10 minutes, I noticed the 100% load by X11. Killing icewm
brought it back to idle, and there it stayed for maybe another hour of
gimp abuse, and everything was cool. I must also mention that without
any wm, gimp worked even smoother.

Then I started icewm again to rearrange the windows, and killed it
again as soon as the windows were in the right pusitions. The load
went up to 100% again and never came back to idle. Killing gimp didn't
bring it back to idle either. So it remained at 100% with the sole
xterm running. Killing X11 was enough to cool it down, but starting it
again with a single xterm and no wm brought it back to 100%.

So this sort of confirms the report that it is possible to have the
hot idle effect with a sole xterm and no wm. I havenr't obesrved it
long enough to know if it would ever arise without more sophisticated,
albeit transient, use of X11; and I don't know enough to say whether
wm has anything to do with that (it is hard to use anything more
complicated than xterm without a window manager). All I can see is
that once the situation arises, it tends to persist.

I have just restarted the system, and it's again running with a single
undecorated xterm, with X11 being essentially idle,  wether or not I
do anything in that xterm or in other apps.

Now, please pardon my ignorance -- I am years of reading away from
understanding any of the X11, wm or osx GUI stuff, but is there such a
thing as event queue? If there is such a thing, or perhaps several,
given what a nice hack XQuartz is, can it (they) be clogged with
something unexpected? I am imagining something that gets inserted into
the queue, then gets "read", whatever that means, but not cleaned up?
Or even not read? Or, can an empty queue look non-empty? Just a WAG
trying to explain why the effect is intermittent, why it is so
drastic, as well as why it tends to persist even after whatever
"thing" responsible for it is gone, and even after X11 is restarted.

Regards,

--Gene


On Mon, Feb 9, 2009 at 2:51 AM, Jeremy Huddleston <jeremyhu at apple.com> wrote:
>
> Someone reported this without quartz-wm running (.xinitrc was just 'exec
> xterm').
>
> Ken, could you please make your ~/.xinitrc just contain this line:
> exec /usr/X11/bin/xterm
>
> Then relaunch X11.app?  You should get an undecorated xterm window.  Can you
> see the 100% CPU usage in this scenario?