Allowing PortGroups to bump port revision

[Joshua Root]

On 2018-1-14 02:19 , Clemens Lang wrote:
> Hi,
> 
> On Sun, Jan 14, 2018 at 12:01:34AM +1100, Joshua Root wrote:
>> portindex isn't slow, mportopen is. You have to evaluate the changed
>> Portfiles before you can extract their info.
> 
> I haven't measures this, but I assume the majority of time in mportopen
> is spent by the sub-interpreter loading the port1.0 package (i.e.
> evaluating the PortSystem 1.0 line in the Portfile). Since this set of
> files should be in the buffer cache after the first Portfile was
> evaluated the problem is probably not the disk speed.
> 
> This could be made much faster if Tcl had a way to 'clone' an
> interpreter that already had port1.0 loaded before running the rest of
> the Portfile. If somebody wants to implement that, that would probably
> improve portindex speeds significantly.

That may indeed help in the general case. However I know that there are
some portfiles that take a lot longer than others, such as the gcc
ports. I'm not sure why.

If someone wants to work on improving this, the first step is of course
to profile.

- Josh