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Re: Parallel processing downgrade

  • To: mathgroup at smc.vnet.net
  • Subject: [mg98904] Re: Parallel processing downgrade
  • From: Bob F <deepyogurt at gmail.com>
  • Date: Tue, 21 Apr 2009 05:10:35 -0400 (EDT)
  • References: <gsh19a$qa$1@smc.vnet.net>

On Apr 19, 11:30 pm, mark mcclure <mcmcc... at unca.edu> wrote:
> The change from Mathematica 7.0.0 to 7.0.1 seems to be a
> downgrade in the area of parallel processing.  Try
> LaunchKernels[8] in both.  Back in good old 7.0.0 you
> get:
> {KernelObject[1, "local"], KernelObject[2, "local"],
>  KernelObject[3, "local"], KernelObject[4, "local"],
>  KernelObject[5, "local"], KernelObject[6, "local"],
>  KernelObject[7, "local"], KernelObject[8, "local"]}
>
> Eight kernels - cool!
>
> In 7.0.1, you get
>
> {KernelObject[1, "local"], KernelObject[2, "local"],
>  KernelObject[3, "local"], KernelObject[4, "local"],
>  $Failed, $Failed, $Failed, $Failed}
>
> A little disappointing.
>
> The results are independent of how many processors your
> computer has.
>
> Mark McClure

Did you change passwords between 7.0.0 and 7.0.1? Seems odd that
without a different password that has a different number of kernels
allowed encoded into it, that you would see this kind of difference.
What platform are you on (Windows, Mac, etc)??

I don't know about the 7.0.0 having 8 kernels available (dont have it
installed any more), but one thing to keep in mind with the new
default of 4 "computation processes" in version 7.0 -- these are NOT
full kernels, they are special Parallel-Only-kernels (well the first
two are regular but the second two are parallel routines only). In
other words try and run 4 notebooks and assign each their own kernel -
you CANNOT do it with the standard license with it's four "computatoin
processes". You can do two, but that is it. If you want to use four
you have to use the new parallel routines in 7.0. So keep this in mind
when you talk about how many kernels that Mathematica now has. They
only let 4 of them run if two or more were invoked from the new 7.0
parallel routines, not from the front end or from the command line.

Notice that Wolfram now refers to these as "Computation Processes" not
as "Processes" like they did on version 6 and earlier I think. I think
these were often called "concurrent kernel processes" or kernels, and
now you have to be careful when comparing the newer "computation
processes" and "controlling processes".

You can purchase additional kernels (in blocks of 4 I believe) if you
need more -- call your Wolfram sales person and get the whole story if
you need more kernels.

-Bob


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