# Julia at Scale

**URL:** https://discourse.julialang.org/c/domain/parallel/34.md

[Latest](https://discourse.julialang.org/latest.md) · [Categories](https://discourse.julialang.org/categories.md) · [Tags](https://discourse.julialang.org/tags.md)

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## [About the Julia at Scale category](https://discourse.julialang.org/t/about-the-julia-at-scale-category/5038)

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**Author:** [@vchuravy](https://discourse.julialang.org/u/vchuravy)\
**Replies:** 0\
**Last updated:** [July 24, 2017, 8:55am UTC](https://discourse.julialang.org/t/about-the-julia-at-scale-category/5038 "2017-07-24T08:55:16Z")

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Julia at Scale is all about running Julia on large parallel distributed computing systems, may it be the cloud or supercomputers. We welcome questions and discussions about how to get started, best practices and challeng…

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## [\[ANN\] Training course “Julia for HPC” in Stuttgart, Germany on Sep 29-Oct 2, 2026](https://discourse.julialang.org/t/ann-training-course-julia-for-hpc-in-stuttgart-germany-on-sep-29-oct-2-2026/137435)

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**Author:** [@carstenbauer](https://discourse.julialang.org/u/carstenbauer)\
**Replies:** 2\
**Last updated:** [June 8, 2026, 12:07pm UTC](https://discourse.julialang.org/t/ann-training-course-julia-for-hpc-in-stuttgart-germany-on-sep-29-oct-2-2026/137435 "2026-06-08T12:07:30Z")

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For the fifth year in a row (see e.g. here or here or here) I’m pleased to annouce that there will be another opportunity to learn more about using Julia for high-performance computing this fall! In collaboration with t…

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## [GSoC 2026: Out-of-Core Computing in Dagger - Initial Prototyping](https://discourse.julialang.org/t/gsoc-2026-out-of-core-computing-in-dagger-initial-prototyping/137161)

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**Author:** [@rainerrodrigues](https://discourse.julialang.org/u/rainerrodrigues)\
**Replies:** 0\
**Last updated:** [May 18, 2026, 11:16am UTC](https://discourse.julialang.org/t/gsoc-2026-out-of-core-computing-in-dagger-initial-prototyping/137161 "2026-05-18T11:16:30Z")

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Hi everyone! I’m Rainer. I’m preparing a GSoC proposal for the Out-of-Core Computing project for Dagger.jl. Coming from a background in mechatronics and embedded systems, dealing with strict hardware memory constraint…

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## [Error using Julia on an HPC cluster: Juliaup configuration is locked by another process, waiting for it to unlock](https://discourse.julialang.org/t/error-using-julia-on-an-hpc-cluster-juliaup-configuration-is-locked-by-another-process-waiting-for-it-to-unlock/118059)

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**Author:** [@squark](https://discourse.julialang.org/u/squark)\
**Replies:** 3\
**Last updated:** [December 25, 2025, 12:55am UTC](https://discourse.julialang.org/t/error-using-julia-on-an-hpc-cluster-juliaup-configuration-is-locked-by-another-process-waiting-for-it-to-unlock/118059 "2025-12-25T00:55:40Z")

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I have been using Julia on an HPC slurm cluster with no problem. However, I was trying to use the MPI.jl package to parallelize my code. The cluster has intel MPI that I have been trying to use without success. I added t…

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## [Lessons learnt and thoughts on deploying Julia and sysimages on AWS](https://discourse.julialang.org/t/lessons-learnt-and-thoughts-on-deploying-julia-and-sysimages-on-aws/130669)

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**Author:** [@ConnectedSystems](https://discourse.julialang.org/u/ConnectedSystems)\
**Replies:** 1\
**Last updated:** [August 29, 2025, 1:57pm UTC](https://discourse.julialang.org/t/lessons-learnt-and-thoughts-on-deploying-julia-and-sysimages-on-aws/130669 "2025-08-29T13:57:17Z")

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I have spent a portion of my time on and off over the past two weeks trying to build docker containers with sysimages to deploy on AWS. Over that time I have run into various issues and thought it worthwhile writing up m…

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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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## [Multithreaded for loops in Julia](https://discourse.julialang.org/t/multithreaded-for-loops-in-julia/130728)

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**Author:** [@random\_guy](https://discourse.julialang.org/u/random_guy)\
**Replies:** 11\
**Last updated:** [July 15, 2025, 1:52pm UTC](https://discourse.julialang.org/t/multithreaded-for-loops-in-julia/130728 "2025-07-15T13:52:21Z")

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Hello everyone, I am a bit new to multithreading and I would like to know what the best way to multithread a for loop is. The unthreaded for loop is the following, where I’ve included in-place matrix modification and th…

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## [SlurmClusterManagers timeout](https://discourse.julialang.org/t/slurmclustermanagers-timeout/130038)

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**Author:** [@marcobonici](https://discourse.julialang.org/u/marcobonici)\
**Replies:** 2\
**Last updated:** [June 19, 2025, 6:59pm UTC](https://discourse.julialang.org/t/slurmclustermanagers-timeout/130038 "2025-06-19T18:59:30Z")

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Hello, I have been trying to run some jobs on a Slurm cluster (specifically, the canadian Narval Cluster of the Research Digital Alliance). Possibly due to my inexperience with it, I encountered some issues (I am not o…

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## [Speeding Up Julia Startup with MPI: Using Scratch Space to Mitigate HDD Access Delay](https://discourse.julialang.org/t/speeding-up-julia-startup-with-mpi-using-scratch-space-to-mitigate-hdd-access-delay/128971)

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**Author:** [@0samuraiE](https://discourse.julialang.org/u/0samuraiE)\
**Replies:** 9\
**Last updated:** [June 5, 2025, 1:36pm UTC](https://discourse.julialang.org/t/speeding-up-julia-startup-with-mpi-using-scratch-space-to-mitigate-hdd-access-delay/128971 "2025-06-05T13:36:11Z")

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Hello everyone, I’m currently experiencing a significant slowdown when launching Julia with MPI on my cluster. I suspect that the issue might be due to the long HDD access times. To mitigate this, I am considering copy…

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## [Timeout issues on slurm cluster](https://discourse.julialang.org/t/timeout-issues-on-slurm-cluster/58303)

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**Author:** [@ffreyer](https://discourse.julialang.org/u/ffreyer)\
**Replies:** 7\
**Last updated:** [June 4, 2025, 9:20am UTC](https://discourse.julialang.org/t/timeout-issues-on-slurm-cluster/58303 "2025-06-04T09:20:33Z")

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I’ve been running into IOError: connect: connection timed out (ETIMEDOUT) with about half my jobs using ClusterManagers on a slurm cluster. This issue started appearing about a month ago with julia 1.3 and ClusterManager…

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## [Fastest way to sample from MVN, changing parameters](https://discourse.julialang.org/t/fastest-way-to-sample-from-mvn-changing-parameters/128145)

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**Author:** [@Daniel\_Johansson](https://discourse.julialang.org/u/Daniel_Johansson)\
**Replies:** 7\
**Last updated:** [May 3, 2025, 4:11pm UTC](https://discourse.julialang.org/t/fastest-way-to-sample-from-mvn-changing-parameters/128145 "2025-05-03T16:11:23Z")

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Hey guys! Does anybody know what is the most efficient way of sampling from a multivariate normal distribution whose parameters are constantly updated. I’m constructing a Gibbs sampler for a MVN whose parameters depend …

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## [Pointers of Float to be used in MPI?](https://discourse.julialang.org/t/pointers-of-float-to-be-used-in-mpi/128146)

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**Author:** [@jsjie](https://discourse.julialang.org/u/jsjie)\
**Replies:** 0\
**Last updated:** [April 17, 2025, 2:46am UTC](https://discourse.julialang.org/t/pointers-of-float-to-be-used-in-mpi/128146 "2025-04-17T02:46:04Z")

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The following is a MWE that fails: using MPI MPI.Init() mutable struct Foo bar::Float64 end rank = MPI.Comm\_rank(MPI.COMM\_WORLD) foo = Foo(rank) println("$(rank)\\t$(foo.bar)") if rank == 0 MPI.API.MPI\_Recv(Re…

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## [HTCondor workflow for "embarrassingly" parallel computations](https://discourse.julialang.org/t/htcondor-workflow-for-embarrassingly-parallel-computations/127314)

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**Author:** [@alexdmeyer](https://discourse.julialang.org/u/alexdmeyer)\
**Replies:** 1\
**Last updated:** [March 26, 2025, 12:40am UTC](https://discourse.julialang.org/t/htcondor-workflow-for-embarrassingly-parallel-computations/127314 "2025-03-26T00:40:44Z")

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Hey Julia Community, I’m currently using HTCondor to run batches of jobs on my university’s computing cluster. The problem I’m working on is “embarrassingly” (a.k.a. “pleasingly”) parallel, in that each job does the sam…

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## [About implementing a shared Julia environment for HPC clusters at CSC](https://discourse.julialang.org/t/about-implementing-a-shared-julia-environment-for-hpc-clusters-at-csc/112217)

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**Author:** [@jaantollander](https://discourse.julialang.org/u/jaantollander)\
**Replies:** 1\
**Last updated:** [March 19, 2025, 7:44am UTC](https://discourse.julialang.org/t/about-implementing-a-shared-julia-environment-for-hpc-clusters-at-csc/112217 "2025-03-19T07:44:37Z")

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Hello! I’m working at CSC, an HPC center in Finland, and I have been installing a shared Julia environment to our HPC clusters (Puhti, Mahti, and LUMI). These clusters use Lmod for module environments and Slurm as the wo…

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## [Removing bounds checking for HPC - \`--check-bounds=unsafe\`?](https://discourse.julialang.org/t/removing-bounds-checking-for-hpc-check-bounds-unsafe/124897)

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**Author:** [@johnomotani](https://discourse.julialang.org/u/johnomotani)\
**Replies:** 51\
**Last updated:** [February 1, 2025, 4:05pm UTC](https://discourse.julialang.org/t/removing-bounds-checking-for-hpc-check-bounds-unsafe/124897 "2025-02-01T16:05:26Z")

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One of Julia’s main purposes is to enable high-performance computing at scale - it’s on the front page (Ecosystem → Parallel Computing at The Julia Programming Language)! However, apparently --check-bounds=no is becoming…

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## [Using multi-node Distributed.jl in a slurm cluster](https://discourse.julialang.org/t/using-multi-node-distributed-jl-in-a-slurm-cluster/121997)

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**Author:** [@CarlosP24](https://discourse.julialang.org/u/CarlosP24)\
**Replies:** 1\
**Last updated:** [January 29, 2025, 8:44am UTC](https://discourse.julialang.org/t/using-multi-node-distributed-jl-in-a-slurm-cluster/121997 "2025-01-29T08:44:48Z")

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I have found that many of the (not so) documented workflows for using Distributed.jl to distribute proccesses in several nodes of a slurm cluster have several drawbacks, specially for clusters that do not allow ssh conne…

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## [DifferentialEquations.jl+MPI.jl+PencilArrays.jl: Lack of scaling observed](https://discourse.julialang.org/t/differentialequations-jl-mpi-jl-pencilarrays-jl-lack-of-scaling-observed/122998)

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**Author:** [@mmesiti](https://discourse.julialang.org/u/mmesiti)\
**Replies:** 20\
**Last updated:** [December 13, 2024, 2:43pm UTC](https://discourse.julialang.org/t/differentialequations-jl-mpi-jl-pencilarrays-jl-lack-of-scaling-observed/122998 "2024-12-13T14:43:54Z")

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I am working on a code that use DifferentialEquations (more precisely, just OrdinaryDiffEqLowOrderRK - thanks for splitting that) and I have done some work to parallelize the computation of the derivative on multiple nod…

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## [Addprocs\_slurm not connecting to all available workers](https://discourse.julialang.org/t/addprocs-slurm-not-connecting-to-all-available-workers/123149)

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**Author:** [@jewh](https://discourse.julialang.org/u/jewh)\
**Replies:** 7\
**Last updated:** [December 4, 2024, 7:17am UTC](https://discourse.julialang.org/t/addprocs-slurm-not-connecting-to-all-available-workers/123149 "2024-12-04T07:17:47Z")

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I’m using Distributed and ClusterManagers to run large numbers of simulations in parallel on my university HPC cluster. Scheduling and job management on the cluster is handled by Slurm. I initialise each of the parallel…

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## [MPIPreferences no longer allows system?](https://discourse.julialang.org/t/mpipreferences-no-longer-allows-system/122475)

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**Author:** [@PetrKryslUCSD](https://discourse.julialang.org/u/PetrKryslUCSD)\
**Replies:** 1\
**Last updated:** [November 10, 2024, 11:12pm UTC](https://discourse.julialang.org/t/mpipreferences-no-longer-allows-system/122475 "2024-11-10T23:12:54Z")

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Sorry: Never mind, it is supposed to be just use\_system\_binary

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## [Help with Multi-GPU FDTD implementation: halo exchange and efficient monitors](https://discourse.julialang.org/t/help-with-multi-gpu-fdtd-implementation-halo-exchange-and-efficient-monitors/121676)

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**Author:** [@lucasgrjn](https://discourse.julialang.org/u/lucasgrjn)\
**Replies:** 1\
**Last updated:** [October 28, 2024, 9:05am UTC](https://discourse.julialang.org/t/help-with-multi-gpu-fdtd-implementation-halo-exchange-and-efficient-monitors/121676 "2024-10-28T09:05:50Z")

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Hi everyone! I am a physicist and photonics engineer. Recently, Meta released a Julia package called Khronos to perform FDTD (Finite-Difference Time-Domain) simulations. The basic idea is to iteratively propagate light …

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## [Julia code on a cluster without Julia installed](https://discourse.julialang.org/t/julia-code-on-a-cluster-without-julia-installed/121267)

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**Author:** [@uri](https://discourse.julialang.org/u/uri)\
**Replies:** 9\
**Last updated:** [October 19, 2024, 7:28pm UTC](https://discourse.julialang.org/t/julia-code-on-a-cluster-without-julia-installed/121267 "2024-10-19T19:28:28Z")

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Hi. I need to run some Julia code on a cluster without Julia installed. I don’t have root permission. Any suggestions. Thanks a lot

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## [Some introductory Julia codes for HPC!](https://discourse.julialang.org/t/some-introductory-julia-codes-for-hpc/121361)

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**Author:** [@hunKing](https://discourse.julialang.org/u/hunKing)\
**Replies:** 0\
**Last updated:** [October 16, 2024, 6:45am UTC](https://discourse.julialang.org/t/some-introductory-julia-codes-for-hpc/121361 "2024-10-16T06:45:14Z")

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Hey folks, I wrote a few codes to serve as a jump start to learning how to use Julia with SLURM managed clusters. I uploaded them to this repository: https://github.com/AtilaSaraiva/Julia-HPC-intro-codes I’ve got a fe…

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## [Write a String with parallel HDF5](https://discourse.julialang.org/t/write-a-string-with-parallel-hdf5/121025)

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**Author:** [@johnomotani](https://discourse.julialang.org/u/johnomotani)\
**Replies:** 1\
**Last updated:** [October 16, 2024, 6:09am UTC](https://discourse.julialang.org/t/write-a-string-with-parallel-hdf5/121025 "2024-10-16T06:09:21Z")

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Does anyone know the ‘correct’ way to write a scalar variable (especially a String) using parallel HDF5? I think I have a way of doing it, but it’s so ugly I’m hoping there’s a better way! The problem: suppose I have a …

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## [How to have each node in a cluster run a parallel job on its own CPUs, using SSH?](https://discourse.julialang.org/t/how-to-have-each-node-in-a-cluster-run-a-parallel-job-on-its-own-cpus-using-ssh/80813)

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**Author:** [@ultrapoci](https://discourse.julialang.org/u/ultrapoci)\
**Replies:** 4\
**Last updated:** [October 14, 2024, 11:05am UTC](https://discourse.julialang.org/t/how-to-have-each-node-in-a-cluster-run-a-parallel-job-on-its-own-cpus-using-ssh/80813 "2024-10-14T11:05:05Z")

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I have access to a cluster with multiple nodes, connected thorugh SSH, each of which has multiple CPUs. My algorithm uses DistributedArrays.jl to create a distributed array and have multiple processes work on it: at the …

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## [Configure Slurm File for Parallelization](https://discourse.julialang.org/t/configure-slurm-file-for-parallelization/121239)

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**Author:** [@benjamin.nunez](https://discourse.julialang.org/u/benjamin.nunez)\
**Replies:** 4\
**Last updated:** [October 13, 2024, 7:41pm UTC](https://discourse.julialang.org/t/configure-slurm-file-for-parallelization/121239 "2024-10-13T19:41:57Z")

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Hello everyone! I am using a computer cluster to parallelize the execution of my Julia code. The partition I am using has a total of 14 nodes, and my goal is to connect to this partition and execute my main.jl file, wh…

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## [How to profile Julia MPI code?](https://discourse.julialang.org/t/how-to-profile-julia-mpi-code/57136)

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**Author:** [@PolarizedPoutine](https://discourse.julialang.org/u/PolarizedPoutine)\
**Replies:** 17\
**Last updated:** [October 3, 2024, 12:16am UTC](https://discourse.julialang.org/t/how-to-profile-julia-mpi-code/57136 "2024-10-03T00:16:05Z")

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How do people usually profile Julia MPI code to find bottlenecks and reduce communication overhead? As an MPI noob I thought there would be some profiler tools out (kinda like cuprof and NVIDIA Nsight) there but they se…

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## [Code that uses MPI.jl does not run on cluster](https://discourse.julialang.org/t/code-that-uses-mpi-jl-does-not-run-on-cluster/118167)

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**Author:** [@Uranium238](https://discourse.julialang.org/u/Uranium238)\
**Replies:** 24\
**Last updated:** [August 26, 2024, 3:04pm UTC](https://discourse.julialang.org/t/code-that-uses-mpi-jl-does-not-run-on-cluster/118167 "2024-08-26T15:04:14Z")

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I have written a version of my code that uses MPI.jl to achieve a potentially large scale parallelization. I already had MPI installed on my PC and used the instructions from here to make sure that the same mpiexec is be…

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## [How to combine MPI non-blocking Isend/Irecv and Julia tasks](https://discourse.julialang.org/t/how-to-combine-mpi-non-blocking-isend-irecv-and-julia-tasks/52524)

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**Author:** [@fverdugo](https://discourse.julialang.org/u/fverdugo)\
**Replies:** 7\
**Last updated:** [August 16, 2024, 8:10pm UTC](https://discourse.julialang.org/t/how-to-combine-mpi-non-blocking-isend-irecv-and-julia-tasks/52524 "2024-08-16T20:10:58Z")

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I would like to hide the MPI calls needed to wait for a non-blocking Isend / Irecv! by using the Julia asynchronous programming capabilities. I can imagine 3 main ways of doing this (see code below), but I am not certai…

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## [Running a function over multiple nodes on a julia cluster, from within a julia script](https://discourse.julialang.org/t/running-a-function-over-multiple-nodes-on-a-julia-cluster-from-within-a-julia-script/118153)

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**Author:** [@eveningsilverfox](https://discourse.julialang.org/u/eveningsilverfox)\
**Replies:** 5\
**Last updated:** [August 14, 2024, 3:27pm UTC](https://discourse.julialang.org/t/running-a-function-over-multiple-nodes-on-a-julia-cluster-from-within-a-julia-script/118153 "2024-08-14T15:27:56Z")

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I have a function whose skeleton looks like this: function inner(a,ij) return a\*ij; end function outer(a,N) arr = zeros(ComplexF64, N); for ij = 1:N arr\[ij\] = inner(a,ij); end return sum(arr) end…

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## [How to improve the scaling of Julia code aimed at multi-node parallelization?](https://discourse.julialang.org/t/how-to-improve-the-scaling-of-julia-code-aimed-at-multi-node-parallelization/118048)

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**Author:** [@Uranium238](https://discourse.julialang.org/u/Uranium238)\
**Replies:** 38\
**Last updated:** [August 14, 2024, 8:56am UTC](https://discourse.julialang.org/t/how-to-improve-the-scaling-of-julia-code-aimed-at-multi-node-parallelization/118048 "2024-08-14T08:56:08Z")

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I have been trying to write a version of my Julia code that can be run in a parallelized manner using multiple nodes at once. After posting this thread I finally have a working version of the code (as given below) Code …

[Next page](https://discourse.julialang.org/c/domain/parallel/34.md?page=1)