Re: [Boost-users] [mapreduce] Prim Calculator

Subject: Re: [Boost-users] [mapreduce] Prim Calculator
From: Christian Henning (chhenning_at_[hidden])
Date: 2009-08-22 14:49:55

I'm afraid to admit that I f***ed up. The program is now working. I
invalidated the iterators with a for loop before the for_each call.
When I remove my for loop, the results are inside the output files.

Cool stuff,
Christian

On Sat, Aug 22, 2009 at 2:15 PM, Christian Henning<chhenning_at_[hidden]> wrote:
> Craig,
>
>>>
>>> Well, it all compiles and runs but the results is empty. I have
>>> intercepted the reduce function and the supplied list is correct.
>>> Meaning all primes are in there. Weird. Dunno what's wrong here.
>>
>> Did you try defining the job to write the results to file? This will work
>> until I fix the iterator issue.
>
> Yes, I'm using reduce_file_output. But all files are empty. Can you
> reproduce that? Please make sure to get the latest from my subversion.
>
>>
>> A small optimization in the is_prime is to check for %2 - this avoids
>> expensive sqrt & loops for even numbers that are always not prime
>>
>> bool const is_prime(long const number)
>> {
>>    if (number == 0 || number == 1)
>>        return false;
>>    else if (number == 2)
>>        return true;
>>    else if (number%2 == 0)
>>        return false;
>>    ...
>> }
>
> Thanks. ;-) Most important for me right now is to learn how to solve
> problems with mapreduce. Ideas for some other problems?
>
> Christian
>