Installing ports in parallel

[James Linder]

On 13/09/2012, at 3:00 AM, macports-users-request at lists.macosforge.org 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port installs where parts of the dependency chains overlapped, and some of those overlapping dependencies were outdated or not installed yet, things did not work.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.

Since you don't believe, why not enable 'Activity Monitor'.
For me a build holds all 4 cores at the red line for a lot of time. Given this the effort to enable multiple builds will clearly not be worth the effort.
Likewise the occasional 8 hour stint (overnight ?) compared to the time to implement the 'feature' and debug/troubleshoot (as explained) is time wasted that I would much prefer to be spent on real problems.

James