On 06/20/2018 04:15 PM, Stephen Gallagher wrote:
On Wed, Jun 20, 2018 at 10:06 AM Mikolaj Izdebski
<mizdebsk(a)redhat.com>
wrote:
> On 06/20/2018 02:30 PM, Petr Ĺ abata wrote:
>> Parallel installation of streams on a single system indeed
>> isn't supported at this point and isn't planned anytime in the
>> near future. In general it's a more complicated problem than
>> it might seem at first.
>
> Could you elaborate and explain what's so complicated about it?
>
The short answer is that there exists no generic solution for
parallel-installation. Many packages rely on well-known resources[1] and
cannot be parallel-installed at all. Other packages *may* support
parallel-installation but consumers must take special steps to enable
support for it.
In general case, when packages conflict, I would agree. But as subject
says, this is about a special case - non-overlapping, non-conflicting
package sets, which can be installed in parallel without taking any
special steps, like java-1.8.0-openjdk and java-11-openjdk that were
brought up in the first message.
I don't have a good link right now, but folks at Red Hat did a
number of
customer studies and determined that in real-world deployments,
parallel-installation was very rarely used. Generally, the OS was
established with a standard set of packages and then anything that needed
an alternate version was deployed as a VM or container.
Some packages are designed to be parallel-installable for a reason -
because users expect and require that. OpenJDK is an example of such
package. Even different version-releases of the same component can be,
by design, installed in parallel.
So, when we started looking at ways to provide alternative software,
we
determined that parallel-installation was a non-goal. Not needing to solve
an unsolvable problem meant that we could focus on the parts that really
matter: allowing people to select which single version of the software
meets their needs.
So the conclusion is that inability to have parallel-installable streams
of the same module is not due to technical difficulties to implement
that feature, but rather a consequence of prioritizing different
requirements.
--
Mikolaj Izdebski
Senior Software Engineer, Red Hat
IRC: mizdebsk