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how to write ParallelSubmit in a Do loop? trying to use up all CPU

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  • Subject: [mg131443] how to write ParallelSubmit in a Do loop? trying to use up all CPU
  • From: alex <0899607 at gmail.com>
  • Date: Sun, 7 Jul 2013 23:20:47 -0400 (EDT)
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when it comes a heavily calculation, it takes time, but not fully cpu usage
i found a scrip using ParallelSubmit, which is quite powerful and really shorten the time in calculating

http://mathematica.stackexchange.com/questions/10969/parallelization-problem-in-linearsolve-and-minimize


t = AbsoluteTime[];
job1 = ParallelSubmit[Table[Prime[k], {k, 1, 2500000}]];
job2 = ParallelSubmit[Table[Prime[k], {k, 2500001, 5000000}]];
job3 = ParallelSubmit[Table[Prime[k], {k, 5000001, 7500000}]];
job4 = ParallelSubmit[Table[Prime[k], {k, 7500001, 10000000}]];
job5 = ParallelSubmit[Table[Prime[k], {k, 10000001, 12500000}]];
job6 = ParallelSubmit[Table[Prime[k], {k, 12500001, 15000000}]];
job7 = ParallelSubmit[Table[Prime[k], {k, 15000001, 17500000}]];
job8 = ParallelSubmit[Table[Prime[k], {k, 17500001, 20000000}]];
{a1, a2, a3, a4, a5, a6, a7, a8} =
 WaitAll[{job1, job2, job3, job4, job5, job6, job7, job8}];
time2 = AbsoluteTime[] - t

t = AbsoluteTime[];





then i try to rewrite the script by using Do loop, so i can just setup the initial and final value then it can be separated into 8 parts automatically , but i failed.


t = AbsoluteTime[];
initial = 1
final = 20000000
step = (final - initial + 1)/8
Clear["job"]
Clear["i"]

Do[job[i]=ParallelSubmit[Table[Prime[k], {k, step*i + 1, step*(i + 1)}]]
 , {i, 0, 7}]

Clear["a"]
Table[a[jj], {jj, 1, 8}] = WaitAll[Table[job[j], {j, 0, 7}]]

time2 = AbsoluteTime[] - t 



it keeps showing Null, it seems that it cant replace the variable in Do loop exactly, it is still a variable. 

how do i rewrite the scrip? to make it be separated into 8 parts automatically? 
thank you for your help ^^



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