[pacman-dev] [PATCH v2 1/3] bacman: allow for parallel packaging

Allan McRae allan at archlinux.org
Thu Sep 1 03:14:24 UTC 2016

On 01/09/16 09:44, Gordian Edenhofer wrote:
> On Thu, 2016-09-01 at 08:28 +1000, Allan McRae wrote:
>> On 01/09/16 08:08, Dave Reisner wrote:
>>> On Wed, Aug 31, 2016 at 11:18:32PM +0200, Gordian Edenhofer wrote:
>>>>>>> The second probably would not be accepted...
>>>>>> I urge you to reconsider. Parallelization increases the speed
>>>>>> of
>>>>>> this
>>>>> I don't think anyone is suggesting that packaging multiple
>>>>> things in
>>>>> parallel isn't useful. I already suggested that nothing needs
>>>>> to be
>>>>> implemented in bacman proper in order for you to parallelize
>>>>> the
>>>>> work.
>>>>> You can write your own "pbacman" as simply as:
>>>>>   for arg; do bacman "$arg" & done; wait
>>>> There is a huge difference between flooding your system with
>>>> ~1000 jobs
>>>> and tightly controlling the maximum number. Adjusting the precise
>>>> number of jobs enables you to organize your resources which
>>>> itself is
>>>> desirable.
>>> Then use a program like 'parallel' which has this sort of knob. I
>>> really
>>> wonder what it is you're doing that requires running bacman with a
>>> large
>>> number of packages with any regularity.
>> Gathering the files etc takes no time.  It is really the compression
>> that is being made parallel.  If only there was a way to set
>> compression
>> to use mutlithreading...
> The actual compression using xz (default) is not necessary the most
> time intensive part. The linux-headers package for example is
> compressed within a few seconds but the whole process before xz is run
> takes way longer. This can be seen with top as an illustration or
> simply by running bacman one time without compression and the other
> with.
> Moreover using bacman to parallelize makes it completely independent
> from the archive format used and still brings gains when recreating
> multiple packages. At the very least it would fill the gap in between
> the compression of multiple packages. Therefore it would be beneficial
> even if compression would take the longest which is doesn't always do.

So read speed is the slow part?   And trying to read more files at the
same time helps?


More information about the pacman-dev mailing list