Re: gdb-ui can't handle mutiple debugging sessions

[Stefan <monnier@iro.umontreal.ca>]

>> When trying to use two debugging sessions at the same time gdb-ui gets
>> completely confused.  As soon as I start the second session all input is
>> sent to it, even when typed in the window of the first session.  This is a
>> serious regression compared the old interface.

> Thats right, gdb-ui can only handle one debugging session at a time. Trying
> to run more seemed to require the code to be a lot more complex and
> at the time only one overlay arrow was available so, in any case the old
> interface didn't do it very well. I have always found the best way to run
> two
> debugging sessions at the same time is to run two versions of Emacs.
> Whats the problem with this approach?

> I don't see this as a serious regression and so far no-one else appears to
> (gdb-ui has been in CVS Emacs for almost two years now). If you
> can convince me otherwise or if others agree with you I will look at
> adding support for multiple sessions. However, I think this would be a
> major task which I could not complete till after the next release.

Do multiple sessions still work (at least as well as before) if you use
`gdb --fullname'?

What's the source of difficulty in supporting multiple sesions with gdb-ui?
My experience in removing the "only one per Emacs process" limitation of
various special modes (such as pcl-cvs) is that it's usually not that hard,
only it requires care (basically: make all the relevant variables
buffer-local in the main buffer and be careful to always select the main
buffer before reading those vars).

In Emacs-21.3, the multiple-session support in gud.el is pretty fragile:
it only works if all the GUD sessions use the same backend (i.e. all gdb,
or all dbx, or all perldb).  That should be added to the TODO (which should
have a KNOWN-BUGS section).



        Stefan