1.5.21-1(?): XWin.exe runs at 50-100% processor usage

[Aaron Miller]

Hi. I don't know whether I've found a bug or whether there's some conflict
between XWin and some other package I have installed or what, and my skill at
programming doesn't extend as far as figuring it out for myself, so I'm
asking. Please slap my hands if I'm being an idiot.

I hadn't updated my cygwin installation for a while, so when I installed some
random package (syslog-ng 1.6.11-1 or so, IIRC), setup took the opportunity to
download and install all the newest fun, including the latest versions of the
various installed xorg packages. Other than the cygwin update, nothing has
recently changed on the machine.

After the restart, I noticed that XWin.exe was using a surprisingly high
percentage of my processor: instead of the '00' percentage usually reported in
Windows task manager when I'm not doing anything involving X, it ran at about
93%, and continued to do so for several minutes -- I gave it plenty of time to
initialize and settle down, and it didn't settle down.

My system is configured to start c:\cygwin\X11R6\bin\startxwin.bat at login
time, so I popped into a command shell, went there, and tried running the
batch file by hand, with the same high-processor-usage result. I killed that
and looked into the batch file; the command it uses to start XWin.exe is
%RUN% XWin -multiwindow -silent-dup-error -clipboard, which I tried by hand.
Doing it that way yielded an XWin instance which ran at only about 46-48%
sustained processor usage.

I have no idea how to interpret strace output, especially when it's just
dumping everything it can to the terminal. Nonetheless, I tried 'strace XWin
-multiwindow -silent-dup-error -clipboard', just to see. Some XWin instances I
start this way behave normally, at least in terms of processor usage; others
go right up to 46-48% or 90-93% and stay there. xterm won't start under any
XWin that's run by strace.

For whatever it's worth, the strace output shows a lot of this:

--- Process 1080, exception C0000005 at 610B41FB
   2324 181975455 [main] XWin 1080 _cygtls::handle_exceptions: In
cygwin_except_handler exc 0xC0000005 at 0x610B41FB sp 0x228400
--- Process 1080, exception C0000005 at 610AC3FA
   2405 181980399 [main] XWin 1080 _cygtls::handle_exceptions: In
cygwin_except_handler exc 0xC0000005 at 0x610AC3FA sp 0x2283F0

These two exception reports repeat at a rate too high for me to eyeball, but
which appears to be at least a hundred or so per second -- I'll happily
provide strace output on request, as well as anything else that'll help.

Unfortunately, I'm not sure what to do to reproduce this problem; I have no
difficulty doing so on my machine, of course, but without updating my other
Cygwin installs, which I'm understandably not sprinting to do, I have no way
of knowing whether this problem will occur anywhere else. The best clue I've
got for a test case is to download and install the latest xorg packages, try
starting XWin, and see what happens.

I've STFW, with little result; I found a thread from May regarding what looked
like it might be a similar problem ('XWin 100% CPU Usage (Remote Desktop)').
In that thread, Larry Hall suggested trying the latest cygwin-1.dll snapshot.
I haven't tried that yet; it's possible it might help, but I tend slightly to
doubt it, as nothing else which uses cygwin-1.dll is giving me any trouble. If
someone with a clue tells me to try it, I'll try it; until then I'd rather
leave well enough alone.

Please find attached output of cygcheck -s -v -r from the machine that's
having the trouble. Apologies for the slight disjointedness of my report, too;
if there's any other information which might be of use, please let me know,
and I'll provide it.

Thank you for your time and attention.

-- Aaron

-------------- next part --------------
An embedded and charset-unspecified text was scrubbed...
Name: cygcheck.out
URL: <http://cygwin.com/pipermail/cygwin-xfree/attachments/20060725/a0144504/attachment.ksh>
-------------- next part --------------
--
Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple
Problem reports:       http://cygwin.com/problems.html
Documentation:         http://x.cygwin.com/docs/
FAQ:                   http://x.cygwin.com/docs/faq/