Installing ports in parallel

[Peng Yu]

On Tue, Sep 11, 2012 at 12:50 PM, Ryan Schmidt <ryandesign at macports.org> wrote:
>
> On Sep 11, 2012, at 11:57, Peng Yu <pengyu.ut at gmail.com> wrote:
>
>> I don't find a way to let port install multiple independent ports in
>> parallel to maximally use the cores on a machine. Is there a way to do
>> so? Thanks!
>
> This used to be allowed (unintentionally, I think) and would sometimes work, as long as the ports you were installing were truly independent of one another (including their complete dependency chains). But as soon as you started trying to do simultaneous port installs where parts of the dependency chains overlapped, and some of those overlapping dependencies were outdated or not installed yet, things did not work. Confusing error messages were printed that users often did not understand.
>
> We "fixed" the problem a few versions of MacPorts by introducing a lock mechanism that ensures that you can only install one port at a time. I miss the parallel install capability we used to have, but appreciate that this reduces the number of confusing problems our users could encounter, and thus decreases the number of problem reports we receive, which frees up our time to work on more interesting problems.

There are many tools out there to handle dependencies for compiling
software and for many other purpose as well. For example, GNU make,
cmake, ant, maven, etc. I think that there should be (at least
theoretically) some way of harness some of these tools to handle
parallel builds of multiple ports even if they share dependency
chains. Whether it is easy to implement is another issue and I don't
know the answer.

My inclination is that the feature that I request can be useful. As I
can port using binaries for only a very small fraction of ports.
Enabling parallel port can truly use all the cores to speed the
process. Recently, I just migrate from Snow Leopard to Mountain Loin,
It took almost 8 hours for me to completely install what had been
previously installed. There should be something done to improve this
process.

-- 
Regards,
Peng