# \#parallel-computing

**URL:** https://discourse.julialang.org/tag/parallel-computing/1557.md

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## [Parallelization in Julia vs C++](https://discourse.julialang.org/t/parallelization-in-julia-vs-c/136083)

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**Author:** [@Rkiefe](https://discourse.julialang.org/u/Rkiefe)\
**Replies:** 21\
**Last updated:** [March 11, 2026, 1:04pm UTC](https://discourse.julialang.org/t/parallelization-in-julia-vs-c/136083 "2026-03-11T13:04:01Z")

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Do you tend to have problems parallelizing thousands of fast computations over a large matrix? I’m going to show a Julia and then a C++ version of the code snippet. I get a lot more performance benefits from parallelizat…

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## [Memory kills this code](https://discourse.julialang.org/t/memory-kills-this-code/133583)

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**Author:** [@raman\_kumar](https://discourse.julialang.org/u/raman_kumar)\
**Replies:** 5\
**Last updated:** [November 3, 2025, 9:33pm UTC](https://discourse.julialang.org/t/memory-kills-this-code/133583 "2025-11-03T21:33:45Z")

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This code is giving accurate plot but needs too much memory and is slow. I have been working since few months to get 3D volume plot of this Astrophysical data linked here. You can download this data by clicking on Downlo…

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## [Different running performance in parallelization of Threads](https://discourse.julialang.org/t/different-running-performance-in-parallelization-of-threads/133397)

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**Author:** [@Xu\_Shan](https://discourse.julialang.org/u/Xu_Shan)\
**Replies:** 22\
**Last updated:** [October 27, 2025, 5:07pm UTC](https://discourse.julialang.org/t/different-running-performance-in-parallelization-of-threads/133397 "2025-10-27T17:07:21Z")

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Hi Guys, I am running a model which use a for-loop to run on 17 independently different sites. Each site does not share memory with each other. But all of the inputs for 17 sites are collected in a list, of which the el…

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## [Asynchronous tasks vs multi-threading](https://discourse.julialang.org/t/asynchronous-tasks-vs-multi-threading/131485)

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**Author:** [@WalterMadelim](https://discourse.julialang.org/u/WalterMadelim)\
**Replies:** 16\
**Last updated:** [August 10, 2025, 10:48pm UTC](https://discourse.julialang.org/t/asynchronous-tasks-vs-multi-threading/131485 "2025-08-10T22:48:01Z")

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Parallel is a section of Julia’s doc containing the following 2 subsections Asynchronous “tasks”, or coroutines Multi-threading I notice that setting JULIA\_NUM\_THREADS to \>1 (proper physical multi-threading) is only r…

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## [Memory problem when using SlurmClusterManager.jl to add workers](https://discourse.julialang.org/t/memory-problem-when-using-slurmclustermanager-jl-to-add-workers/131039)

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**Author:** [@CeterisPartybus](https://discourse.julialang.org/u/CeterisPartybus)\
**Replies:** 6\
**Last updated:** [July 28, 2025, 5:32pm UTC](https://discourse.julialang.org/t/memory-problem-when-using-slurmclustermanager-jl-to-add-workers/131039 "2025-07-28T17:32:11Z")

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I am new to using Distributed.jl on a cluster. I am trying to run jobs on a cluster with multiple nodes. Even though I specify a single node my Julia program should run on in the batch file, there seems to be a problem t…

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## [How to make parallel within the parallel?](https://discourse.julialang.org/t/how-to-make-parallel-within-the-parallel/130642)

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**Author:** [@Xu\_Shan](https://discourse.julialang.org/u/Xu_Shan)\
**Replies:** 0\
**Last updated:** [July 11, 2025, 1:22pm UTC](https://discourse.julialang.org/t/how-to-make-parallel-within-the-parallel/130642 "2025-07-11T13:22:41Z")

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Hi Guys, Right now I am running a model optimization to optimize one set of parameter for several sites (in total 47 sites). Site computation is independent with each other. I am using CMAES to minimise the cost. For no…

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## [How to make a variable available on all processes (when using Distributed)](https://discourse.julialang.org/t/how-to-make-a-variable-available-on-all-processes-when-using-distributed/128460)

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**Author:** [@Torkel](https://discourse.julialang.org/u/Torkel)\
**Replies:** 21\
**Last updated:** [April 28, 2025, 8:43am UTC](https://discourse.julialang.org/t/how-to-make-a-variable-available-on-all-processes-when-using-distributed/128460 "2025-04-28T08:43:21Z")

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I have a workflow which first does some preparations. Next, it does a heavy bit of computing which I would like to carry out in parallel. In practise it looks something like: # Fetch packages. @everwhere using Distribut…

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## [Floops multithreading HasBoxedVariableError](https://discourse.julialang.org/t/floops-multithreading-hasboxedvariableerror/127139)

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**Author:** [@s\_amap](https://discourse.julialang.org/u/s_amap)\
**Replies:** 7\
**Last updated:** [March 19, 2025, 3:54pm UTC](https://discourse.julialang.org/t/floops-multithreading-hasboxedvariableerror/127139 "2025-03-19T15:54:34Z")

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I’ve been trying to adjust a parallel loop after some changes, and I need some clarification to make sure I’m not at risk of false sharing. The loop conceptually works like this: object # holds a state, which is a tupl…

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## [Alternatives for parallel programming with nvidia cards with CUDA versions lower than 9-10](https://discourse.julialang.org/t/alternatives-for-parallel-programming-with-nvidia-cards-with-cuda-versions-lower-than-9-10/118345)

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**Author:** [@Alex\_73](https://discourse.julialang.org/u/Alex_73)\
**Replies:** 0\
**Last updated:** [August 18, 2024, 8:36pm UTC](https://discourse.julialang.org/t/alternatives-for-parallel-programming-with-nvidia-cards-with-cuda-versions-lower-than-9-10/118345 "2024-08-18T20:36:43Z")

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I’m starting to study parallel programming and would like to use the nvidia drivers. In my case, I have a GeForce 820M video card with drivers 390.157, the latest for this hardware. I also tried to install the CUDA versi…

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## [Parallel computation to speed up for loops](https://discourse.julialang.org/t/parallel-computation-to-speed-up-for-loops/126006)

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**Author:** [@AP9](https://discourse.julialang.org/u/AP9)\
**Replies:** 3\
**Last updated:** [February 18, 2025, 7:00pm UTC](https://discourse.julialang.org/t/parallel-computation-to-speed-up-for-loops/126006 "2025-02-18T19:00:02Z")

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I am computing the Lyapunov exponents in 2D for the system below, by doing a for loop over two parameters (ωA, A) and it takes a really long time. using Parameters, ChaosTools, DifferentialEquations, Distributed, Shared…

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## [Using @distributed for loop](https://discourse.julialang.org/t/using-distributed-for-loop/117831)

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**Author:** [@Sahil\_Khan](https://discourse.julialang.org/u/Sahil_Khan)\
**Replies:** 10\
**Last updated:** [August 5, 2024, 10:26am UTC](https://discourse.julialang.org/t/using-distributed-for-loop/117831 "2024-08-05T10:26:41Z")

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Hello everyone, Can someone point out why following setup is not working ? Issue is that I want to copy function result in xm variable that is defined by @everywhere to not have issue with workers. But when I run loop i…

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## [(Course) Parallel Computing in Julia](https://discourse.julialang.org/t/course-parallel-computing-in-julia/117383)

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**Author:** [@Noel\_Araujo](https://discourse.julialang.org/u/Noel_Araujo)\
**Replies:** 0\
**Last updated:** [July 23, 2024, 12:38pm UTC](https://discourse.julialang.org/t/course-parallel-computing-in-julia/117383 "2024-07-23T12:38:19Z")

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Hello everyone After years of topics asking for help, finally I am posting something different. I have an Udemy course in Parallel Computing, and I made a real effort to showcase something different from computing Pi o…

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## [Looking to parallelize (not parametrize) the solution to a large and highly stiff ODE system](https://discourse.julialang.org/t/looking-to-parallelize-not-parametrize-the-solution-to-a-large-and-highly-stiff-ode-system/116727)

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**Author:** [@balaji\_sriram](https://discourse.julialang.org/u/balaji_sriram)\
**Replies:** 7\
**Last updated:** [July 13, 2024, 12:41pm UTC](https://discourse.julialang.org/t/looking-to-parallelize-not-parametrize-the-solution-to-a-large-and-highly-stiff-ode-system/116727 "2024-07-13T12:41:42Z")

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I am solving a system of linear differential equations (of type \[dx/dt\]= \[Jacobian\]\*\[ x \] ) with about 1 million simultaneous differential equations. The system is highly stiff and the jacobian is sparse and banded. I us…

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## [@everywhere works, sort of](https://discourse.julialang.org/t/everywhere-works-sort-of/116746)

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**Author:** [@ilovemath](https://discourse.julialang.org/u/ilovemath)\
**Replies:** 2\
**Last updated:** [July 8, 2024, 6:29am UTC](https://discourse.julialang.org/t/everywhere-works-sort-of/116746 "2024-07-08T06:29:36Z")

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I am working on setting up a parallel code, and I am putting in one piece at a time to make sure I actually understand how to do this properly. Primarily, I put the following piece of code in to Julia on the front end o…

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## [\`MPI.jl\` RMA function's usage](https://discourse.julialang.org/t/mpi-jl-rma-functions-usage/115328)

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**Author:** [@Devansh1106](https://discourse.julialang.org/u/Devansh1106)\
**Replies:** 11\
**Last updated:** [June 7, 2024, 2:39pm UTC](https://discourse.julialang.org/t/mpi-jl-rma-functions-usage/115328 "2024-06-07T14:39:35Z")

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using MPI MPI.Init() comm = MPI.COMM\_WORLD rank = MPI.Comm\_rank(MPI.COMM\_WORLD) size = MPI.Comm\_size(MPI.COMM\_WORLD) buf = fill(0, 10) win = MPI.MPI\_Win MPI.API.MPI\_Win\_allocate(10\*sizeof(Int), sizeof(Int), MPI.INFO\_NU…

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## [Several questions on distributed computing from a beginner](https://discourse.julialang.org/t/several-questions-on-distributed-computing-from-a-beginner/114620)

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**Author:** [@WuSiren](https://discourse.julialang.org/u/WuSiren)\
**Replies:** 21\
**Last updated:** [May 28, 2024, 3:00pm UTC](https://discourse.julialang.org/t/several-questions-on-distributed-computing-from-a-beginner/114620 "2024-05-28T15:00:53Z")

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Hi, everyone! I’d like to ask several questions that have confused me very much during my learning distributed computing as a complete beginner. So I came here looking for some confirmation, and also hope it can help oth…

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## [Can I use \`pmap\` on a recursive program?](https://discourse.julialang.org/t/can-i-use-pmap-on-a-recursive-program/114684)

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**Author:** [@WuSiren](https://discourse.julialang.org/u/WuSiren)\
**Replies:** 1\
**Last updated:** [May 25, 2024, 6:46am UTC](https://discourse.julialang.org/t/can-i-use-pmap-on-a-recursive-program/114684 "2024-05-25T06:46:16Z")

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Can I use pmap on a recursive program? Take the following recursive function as an example: using Distributed addprocs(3) function mymax(x) n = length(x) if n == 1 x\[1\] else y = pmap(mymax, \[…

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## [\`KeyError\` when using \`pmap\`](https://discourse.julialang.org/t/keyerror-when-using-pmap/114464)

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**Author:** [@WuSiren](https://discourse.julialang.org/u/WuSiren)\
**Replies:** 3\
**Last updated:** [May 20, 2024, 3:42am UTC](https://discourse.julialang.org/t/keyerror-when-using-pmap/114464 "2024-05-20T03:42:19Z")

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I’m trying to use pmap form Distributed.jl for parallel computing in the runtests.jl file of a package (MyPkg) that is in development. The code is like: # runtests.jl using Distributed: @everywhere, addprocs, pmap usin…

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## [Abstract - Programming Parallel Computers with Julia](https://discourse.julialang.org/t/abstract-programming-parallel-computers-with-julia/111326)

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**Author:** [@benslinux](https://discourse.julialang.org/u/benslinux)\
**Replies:** 1\
**Last updated:** [March 17, 2024, 4:04pm UTC](https://discourse.julialang.org/t/abstract-programming-parallel-computers-with-julia/111326 "2024-03-17T16:04:28Z")

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Came upon this abstract while investigating whether the Julia language had ever been applied in attempting to solve the ‘Three Body Problem’ - though this paper doesn’t address that, it’s interesting in that it really pu…

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## [Julia Slurm Output with MPI](https://discourse.julialang.org/t/julia-slurm-output-with-mpi/111635)

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**Author:** [@erny123](https://discourse.julialang.org/u/erny123)\
**Replies:** 0\
**Last updated:** [March 15, 2024, 12:32am UTC](https://discourse.julialang.org/t/julia-slurm-output-with-mpi/111635 "2024-03-15T00:32:42Z")

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I have a simple script to use in slurm and I’m having trouble understanding the output: #MPItest.jl using MPI println("Testing MPI") That I run on slurm with the following sbatch script: #!/bin/bash #SBATCH -p free…