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Questions tagged [parallelization]

Questions on parallel computing in Mathematica.

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45
votes
1answer
2k views

Transferring a large amount of data in parallel calculations

Bug fixed in version 11.1 Functions like MemberQ, FreeQ, etc. no longer unpack. Yay! This question is inspired by one of @...
41
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1answer
4k views

Why won't Parallelize speed up my code?

What reasons are there that can cause parallelized Mathematica code not to run with full performance?
32
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4answers
2k views

How to collect result continuously (interruptible calculation) when running parallel calculations?

This is the most common pattern to compute a table of results: Table[function[p], {p, parameters}] (regardless of how it's implemented, it could be a ...
13
votes
2answers
3k views

ParallelTable and Table do not give same result

I have a question regarding the use of Parallelize. In the help one can read that “Parallelize[Table[expr,iter, …]] (which is ...
43
votes
3answers
4k views

Are built-in Mathematica functions already parallelized?

I've been noticing something strange since updating to Mathematica 8, and that is that occaisionally I'll see that the MathKernel is using up to 800% CPU in my Activity Monitor on OS X (I have 8 cores)...
36
votes
3answers
4k views

Monitor doesn't work with ParallelTable

I can't monitor ParallelTable: Monitor[ParallelTable[Pause[3]; i, {i, 1, 10}], i] just displays i until it is finished. Do ...
12
votes
3answers
620 views

Why is this parallel evaluation with Dispatch[] so slow?

Can you efficiently parallelize this? The parallel versions are much slower than the sequential version, and I'm not sure why. Does SetSharedVariable allow ...
7
votes
1answer
271 views

Register “initialization code” to run on any newly started parallel kernel

Is it possible to register a some "initialization code" to be run on any newly started parallel kernel? This would be similar to how ParallelNeeds registers a ...
9
votes
3answers
2k views

Which processor and graphics card to use for my Mathematica license

Does my Mathematica license support processors with 8 cores? I have to choose between one of the following processors: Intel® Xeon® E5-1630 v4 Prozessor (4 cores, 3,7 GHz, 4,0 GHz Turbo) Intel® ...
61
votes
4answers
4k views

Speeding up this fractal-generating code

I used the code below (which is a sample from this gist containing more similar code) in my answer to my own question about Mandelbrot-like sets for functions other than the simple quadratic on Math....
43
votes
4answers
1k views

Parallelize evaluation of function with memoization

I have a complicated function that I need multiple times, so I want to memoize it and have the first evaluation done in parallel. Unlike in my example below it's not a continuous function, so ...
43
votes
5answers
4k views

Is it possible to speed up ContourPlot on multi-core machines?

It is not very difficult to face a function for which ContourPlot works too slow. And it seems natural that this function can be parallelized well. Anyway, naive <...
15
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6answers
1k views

Efficient conditional Mean[] on a large data set

Consider a list, AK6, that has 382 sublists of length varying from 2500 to 3000. Each "subsublist" is as such : ...
12
votes
1answer
1k views

How to run mathlink external commands in parallel?

I have an external function called increment (for the sake of illustration) that I call from Mathematica using MathLink. I.e., ...
17
votes
1answer
2k views

Does Mathematica take advantage of hyper-threading (if it is available)?

I do not know much about computer architecture, but some Intel processors have hyper-threading technology, which can apparently improve parallelization for applications that take advantage of it. In ...
9
votes
4answers
939 views

Efficient way to utilise Parallel features to make use of many cores

Let's say I have 100 cores/kernels as my disposal and want to compute a function of two variables f[x,y] over {x,1,10}, ...
16
votes
3answers
849 views

Package found with `Needs`, but not with `ParallelNeeds`

I want to use a self-written package in a parallel computation. However while Needs["mypackage`"] works without problems, ...
13
votes
2answers
3k views

Writing data to a common file during parallel processing

I am executing a loop, and in each loop I have to store a parameter in a file. It is like ...
6
votes
1answer
536 views

Cell evaluation and parallel kernels

Is it possible to simply force Mathematica to evaluate one cell with let's say kernel A and another cell with kernel B etc. so that they can be evaluated in parallel? There is a similar answer here ...
4
votes
2answers
309 views

Elegant way to partition list to be faster than `ParallelTable` (using `ParallelSubmit`), or some alternative?

Suppose you have a function fun[x_] := (Pause[.05*x]; x^2); of which you know that its evaluation time increases with its argument - in this case obviously ...
7
votes
1answer
195 views

Local logfiles for remote kernels

I'd like remote slave kernels to produce log files on my local machine, subject to the following constraints: 1) I don't want to install a distributed filesystem or do other administrative work on ...
41
votes
2answers
2k views

Mma 10: Half the parallel power (Macs)?

Here is a comparison of the parallel kernels launched under Mathematica under v9 and v10, on the same identical current 2014 R2-D2 Mac Pro ... [ Update: Valerio has commented that the same issue ...
13
votes
0answers
4k views

Threads vs Cores: How many kernels need to launch in parallel Mathematica?

I have a dual-core intel machine. I would like to test how many parallel local kernels should be launch to get the optimized performance. Knowing that the HyperThreading technology of Intel could run ...
11
votes
1answer
869 views

Parallel optimization of Markov Chain Monte Carlo

I'm trying to reduce the computation time of a MCMC simulation. Essentially I have a set of particles performing a random walk in a periodic random potential. The particles are independent and every ...
8
votes
1answer
1k views

Is there a method to send different Cell evaluation to different core?

I am running Mathematica on a computer with multi CPU and every CPU has multicore. I am wondering if there exist a method to send different cell evaluation to different core? So if I already have a ...
8
votes
2answers
2k views

Filling global arrays in parallel calculations

I want to parallelize heavy computations which has to be done many times, the result should be arrays of data. Each calculation does not depend on others (but uses the same variables though). The ...
5
votes
2answers
723 views

NDSolve in Mathematica won't use all the cores avaiable

When I solve a system of differential equations in Matlab, the task manager shows that all the CPU cores are in use. This is not true when I solve the same system in Mathematica. I have six cores. ...
6
votes
1answer
508 views

How to avoid unpacking from Language`ExtendedFullDefinition

Consider this code: LaunchKernels[]; On["Packing"] a = RandomReal[{0., 1.}, {64, 30000}]; ParallelMap[Fourier, a]; // AbsoluteTiming Developer...
4
votes
2answers
307 views

Mysterious behaviour of ParallelTable

This question is related to Export bug in combination with ParallelTable?. The following code shows an even stranger bug than in the upper question. The y-axis should always be logarithmic, but in ...
2
votes
1answer
183 views

Changing a Part of a variable within ParallelDo

I want to evaluate nested do as a parallel computations. My formula looks like: ...
18
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3answers
2k views

Mathematica Parellelization on HPC

I'm currently using Mathematica on a High Performance Cluster (HPC) which consists of many compute nodes each with around 16 cores. I currently run my Mathematica script on 20 of the nodes that ...
27
votes
2answers
4k views

List of Parallelize[]-able functions

The question is clear and is inspired by this question and the first comment on this question. Although there are many tricks for parallelizing things that are not ...
17
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5answers
2k views

Connecting to and disconnecting from a continuously running kernel, on demand

I realized that there are lots of advantages to driving C/C++/FORTRAN code directly from Mathematica as LibraryLink functions (instead of running them from the command line or a shell script, as I ...
19
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2answers
666 views

Partial Differential Equation in Parallel

is there any native way to implement multi-core parallel solving of PDE in Wolfram Mathematica? WM 10 now supports Finite Elements Method, but it is actually useless without parallelization. Usually ...
11
votes
1answer
2k views

Wolfram Light Weight Grid and parallel computing

I have attempted to set up and use the Wolfram Lightweight Grid Manager so I can do parallel computing from Mathematica using 2 remote processors on another machine on my local network. My ...
14
votes
1answer
2k views

ParallelEvaluate for function minimization

Is there a parallelized version of a minimization routine available in Mathematica? The objective function is non-linear and the gradients have to be numerically computed. Every function evaluation ...
12
votes
1answer
2k views

Nesting Parallel processes

I just attempted to run code that had nested ParallelMap[] functions. It generates the error message: ParallelMap::subpar: Parallel computations cannot be nested; proceeding with sequential ...
9
votes
1answer
788 views

PrintTemporary in ParallelTable

I thought of a possible answer to Monitor doesn't work with ParallelTable but it doesn't work as I hoped it would. This accumulates print cells instead of deleting them as intended. Can it be ...
8
votes
1answer
298 views

Export bug in combination with ParallelTable?

I am programming with Mathematica 10.3.1.0 on Windows 10 Professional 64 Bit and have an i7-4940-MX 3,1 GHz processor (4 cores). When I use in the example code below ...
16
votes
1answer
4k views

Parallelizing Numerical Integration in Mathematica

I have an ugly, six dimensional function that I need to integrate numerically. It works, but it currently take twelve hours to complete the calculation. Is there any good way to parallelize the ...
5
votes
2answers
341 views

Do SetSharedVariable/SetSharedFunction ruin the benefits of ParallelTable?

Edit: I changed the sample code to get at my question better. Slowdown due to accessing a shared variable is a much more relevant issue (to me at least) than slowdown due to writing to a shared ...
5
votes
1answer
2k views

Why is parallel slower?

I always assumed that distributing a computation is faster, but it isn't necessarily true. When I do Sum[i,{i,10^4}] I retrieve an answer much faster then if I do <...
22
votes
2answers
751 views

Restarting Mathematica automatically

I run a large computation in a loop. At each cycle of the loop I produce large arrays that I save on a disk. At each cycle I would like to Quit Mathematica and ...
20
votes
2answers
3k views

Parallelization problem in LinearSolve and Minimize

My CPU has got 8 cores (it is Intel Core i7-2600 3.40 GHz). When I try to solve a linear matrix equation using LinearSolve for large matrices, Mathematica just uses 4 cores to solve the problem (CPU ...
16
votes
2answers
1k views

Speeding up random walk for many particles

I am trying to speed up this code for many particles to take a random walk. I'm not sure why it is so slow for such a simple task. I got a few hints from colleagues to reduce the precision of the ...
14
votes
1answer
259 views

DistributeDefinitions and synchronization in Mathematica 10

The command DistributeDefinitions[z] installs all current definitions for z on the local kernels. A simple example: we assign ...
15
votes
4answers
508 views

How can we implement “Sleep Sort”?

Inspired by Implement Sleep Sort: Sleep Sort is an integer sorting algorithm I found on the Internet. It opens an output stream, and for each input numbers in parallel, delay for the number seconds ...
10
votes
1answer
123 views

How to ensure that a package is always loaded on startup, even in parallel kernels?

Is there a robust way to ensure that a package is always loaded on startup, even in parallel kernels? Parallel kernels do not read Kernel/init.m.
11
votes
1answer
275 views

Can Predict/Classify be parallelized?

Being able to parallelize Predict /Classify would be useful on multiple fronts: Performance/Scale Streaming Pedagogical ...
10
votes
2answers
462 views

ParallelTable behaves differently when it is run inside a package

I've been butting my head against some very weird behaviour by ParallelTable, and its interaction with packages, over the past few weeks, and making relatively ...