[Xastir] Fwd: [Bug 454740] [NEW] xastir consumes CPU time in X11 socket I/O

[James Cameron]

G'day,

I've reviewed the Xastir source and the behaviour of the inner event
loop in light of the problem reported by Kevin.

I've tried to reproduce the 10% CPU utilisation, but only managed this
on a particularly old CPU.  On a modern CPU from 2006, the utilisation
is under 1%, though strace does indeed show a regular wake-up of the
process.

Xastir is an OSF/Motif based application with POSIX threads.  It is
built with the LessTif library.  The main function delegates event
handling to the XtAppMainLoop function in the X toolkit.  Xastir doesn't
directly manage the event queue itself.

Kevin's observations about CPU utilisation will be dependent on:

1.  the speed of the CPU he is running Xastir on,

2.  the kernel,

3.  the POSIX threading implementation (libpthreads from libc6 package),

4.  the LessTif implementation (libXm from lesstif2),

5.  the X toolkit implementation (libXt from libx6),

To locate the cause of the change from the older Ubuntu version to the
newer, one potential method is to step-wise upgrade a test system,
replacing first the Xastir, then lesstif2, then libx6, then libc6, and
finally the kernel.  At each point the CPU utilisation of Xastir can be
checked.

You might want to check for other bugs reported against other programs
that use the lesstif2 package.  A regression in the other packages is
equally likely.

-- 
James Cameron
http://quozl.linux.org.au/