Thread-safety issues in QtHandles

[Michael Goffioul]

Hi,

As you might know, I've designed QtHandles to run the UI in a separate
thread from octave (which provides a much more responsive interface).
Unfortunately, octave code is not thread-safe (for instance the
internal reference counting system is not) and despite all my efforts
to put guards to avoid race conditions, I experience crashes randomly
within QtHandles under medium/heavy load. This is pretty difficult to
track down as this happens randomly, is not reproducible and usually
disappears when I run within a debugger or valgrind.

To to some investigation, I'd like to block the octave REPL loop
(basically using the graphics lock), but I'm not sure where to put
that. Any pointers in the internals of the REPL loop would be greatly
appreciated.

Michael.