Re: threads and target-function-calls

[Andrew Cagney <ac131313 at redhat dot com>]

> Michael Snyder wrote:
>
> > Andrew Cagney wrote:
> > >
> > > > Hey folks,
> > > >
> > > > Did you know that (at least on x86 linux), if you have a multi-thread
> > > > program and you execute a target function call, all the threads get to
> > > > run?  Doesn't that seem like a bad thing?  Wouldn't we really rather
> > > > only run the thread that is executing the target function call?
> > >
> > > Ha!  That's just the start.  Doing nested inferior function calls on
> > > alternative threads scrables the dummy frame cache:
> > > http://sources.redhat.com/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gdb&pr=468
> > But... that's just sick.   ;-(
> > Wait -- you can't do that.  It isn't meaningful to change threads
> > and then continue/whatever.  It assumes gdb has more control over
> > scheduling than it actually has.
>
> Oh, I think I misunderstood.  You have in mind this:
> 	(gdb) print foo()
> 	[switching thread to xyz]
> 	Breakpoint 2 in foo ()
> 	(gdb) print bar()
>
> not this:
> 	(gdb) print foo ()
> 	breakpoint 2 in foo()
> 	(gdb) thread xyz
> 	(gdb) print bar()
>
> right?
Either.  Or even things like:

	(gdb) print foo()
	[new thread xyx]
	Thread xyz hit breakpoint 2 in foo()
	(gdb) print bar()

(there was talk of trying to only allow one thread to run).

Andrew