Parallel.For executes a for loop in which iterations may run in parallel to each other.
Parallel.For executes a for loop in which iterations may run in parallel to each other.
Questions tagged [parallel-for]
98 questions
3
votes
3 answers
OpenMP parallel for with floating-point range
I have the following program:
int main(){
double sum=0;
#pragma omp parallel for reduction(+:sum)
for(double x=0;x<10;x+=0.1)
sum+=x*x;
}
When I compile it, I get the error invalid type for iteration variable ‘x’.
I take this to mean…
Richard
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3
votes
2 answers
OpenCV parallel_for not using multiple processors
I just saw in the new OpenCV 2.4.3 that they added a universal parallel_for. So following this example, I tried to implement it myself. I got it all functioning with my code, but when I timed its processing vs a similar loop done in a typical serial…
blorgggg
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2
votes
2 answers
allocating memory per thread in a parallel_for loop
I originally have a single-threaded loop which iterates over all pixels of an image and may do various operation with the data.
The library I am using dictates that retrieving pixels from an image must be done one line at a time. To this end I…
Rotem
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2
votes
1 answer
Fastest way of converting image to grayscale using certain coefficients
I need to convert a cv::Mat into grayscale using a custom formula. Each channel of the input matrix has to be multiplied by a certain coefficient.
This is a pseudocode of the operation:
Y = 0.2126*R + 0.7152*G + 0.0722*B
Input matrix is CV_32FC3…
user3501283
- 23
- 3
2
votes
3 answers
Adding double within a parallel loop - std::atomic
I have a parallel code that does some computation and then adds a double to an outside-the-loop double variable. I tried using std::atomic but it does not have suport for arithmetic operations on std::atomic < double > variables.
double dResCross =…
Zdeny
- 65
- 4
2
votes
1 answer
Efficient parallelization of operations on two dimensional array operations in python
I'm trying to parallelize operations on two dimensional array using joblib library in python. Here is the code I have
from joblib import Parallel, delayed
import multiprocessing
import numpy as np
# The code below just aggregates the base_array to…
Ram
- 55
- 8
2
votes
2 answers
C++ How can I run three diffrent parallel_for functions at once apart from using tbb::task_group?
I have code where I have to run parallel_for (independent from each other) at once parallely.
Code is something like:
tbb::parallel_for(range1,func1());//first
tbb::parallel_for(range2,func2());//second
tbb::parallel_for(range3,func3());//third
I…
Vibhor
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- 5
2
votes
0 answers
Unidentifiable error in parallel_for
I'm trying to learn how to use a parallel_for loop for simple tasks. I am trying to use the following code:
Concurrency::parallel_for(int(0), 50, [&](int i)
{
try
{
printf("%d,", i);
}
catch (exception e)
{
…
SFX
- 139
- 10
2
votes
2 answers
Parallel.For SendAsync to BufferBlock to Async Transform?
I am learning about the TPL Dataflow Library. So far it's exactly what I was looking for.
I've created a simple class (below) that performs the following functions
Upon execution of ImportPropertiesForBranch I go to a 3rd party api and get a list…
madebybear
- 359
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2
votes
0 answers
What's the best way to return values from parallel_for
I have simple parallel_for loop and results of every iteration I am inserting to concurrent_unordered_map. I see that inserting makes my code much slower. So what is the best way to return pairs from parallel_for to unordered_map? I was trying with…
Queen
- 171
- 1
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2
votes
3 answers
Parallel.For as opposed to for loop
I am experimenting with parallel programming. I have a normal loop:
for (int i = 0; i < 100000; i++)
{
Console.WriteLine("Thread ID: {0} and i is " + i + " Time Elapsed: " + sw.Elapsed,
Thread.CurrentThread.ManagedThreadId);
}
This…
Mage
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2
votes
1 answer
Parallelization of a Genetic Algorithm in Matlab
I'm writing a parallel Genetic Algorithm in Matlab, specifically a Dual Species Genetic Algorithm (DSGA) (more information can be found in this paper here), and I'm having some trouble parallelizing part of the code.
Now I'm a physics and math…
Grant Williams
- 1,379
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2
votes
1 answer
Could this WPF code benefit from Parallel.For and how?
I'm wondering if there is a way to convert this so it would be more performant
by using a Parallel.For for example.
public FrameworkElement FindIntersectingElement(Rect rectangle, UIElement activeElement)
{
foreach (var child in…
TimothyP
- 18,775
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2
votes
1 answer
Replacing TBB parallel_for with OpenMP
I'm trying to come up with an equivalent replacement of an Intel TBB parallel_for loop that uses a tbb::blocked_range using OpenMP. Digging around online, I've only managed to find mention of one other person doing something similar; a patch…
NobodyNothing
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2
votes
2 answers
Converting a for loop into Task.Parallel.For
I have a procedure bool IsExistImage(int i) . the task of the procedure to detect an image and return bool whether it exist or not.
i have a PDF of 100+ pages which i split and send only the file name through the method. file names are actually the…
Abdur Rahim
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