Re: Tools to debug multiple cores/processes at the same time?

On Wed, 2021-08-18 at 16:53 -0400, Paul Koning wrote:
> There is multiple target support, which I haven't had a chance to try
> yet but from what I remember reading is a recently added GDB
> feature.  It should handle your case plus even stranger ones, such as
> multiple processes running different code, or even running on
> different instruction sets.  It's just what you need for debugging
> distributed applications.

Yeah, I saw that, and it might be the kernel of something that could
support what I'm talking about, except I don't think it manages
different "convenience variable namespaces" per inferior.

But the main thing is it doesn't seem like it supports running the same
command in all inferiors, other than by manually setting each one and
running the command.  Maybe some kind of embedded Python facility could
be created to do this, such as John mentions... I'm not sure what the
python support is currently for multiple inferiors.

Let me give an example of a debugging session:

* start a session with 3 core files

* run a command that shows info about each core (assume a python
"showinfo" command that show all threads with some details about each
one).  Maybe a command like:
  (gdb) all: showinfo
  i1: <info>
  i2: <info>
  i3: <info>

* For each core, go to a certain thread (of course the thread numbers
will be different in each core):
  (gdb) i1: thr 7
  (gdb) i2: thr 9
  (gdb) i3: thr 23

* Run a command that returns some value and stores it in a convenience
variable, on all cores:
  (gdb) all: set $v = $findstuff()

* Run a command that shows some value, on all cores:
  (gdb) all: p $v->someDetail
  i1: $1 = 7
  i2: $1 = 44
  i3: $1 = 165

I dunno, something like that.  Alternatively maybe it would be simpler
for output for each inferior to go to a separate terminal or whatever.