# Latest **URL:** https://melissa.discourse.group/latest.md [Latest](https://melissa.discourse.group/latest.md) · [Categories](https://melissa.discourse.group/categories.md) · [Tags](https://melissa.discourse.group/tags.md) --- ## [Sarting Melissa Discourse](https://melissa.discourse.group/t/sarting-melissa-discourse/7)
**Author:** [@system](https://melissa.discourse.group/u/system)\ **Replies:** 0\ **Last updated:** [February 3, 2023, 5:42am UTC](https://melissa.discourse.group/t/sarting-melissa-discourse/7 "2023-02-03T05:42:09Z")
Welcome to Melissa Discourse to discuss any topic related to the development and use of the Melissa framework for large scale ensemble run and online data processing. --- ## [New spack package is available for installation](https://melissa.discourse.group/t/new-spack-package-is-available-for-installation/64)
**Author:** [@AbhishekP](https://melissa.discourse.group/u/AbhishekP)\ **Replies:** 0\ **Last updated:** [August 6, 2026, 10:55am UTC](https://melissa.discourse.group/t/new-spack-package-is-available-for-installation/64 "2026-08-06T10:55:51Z")
The old spack packages: melissa py-melissa-core will be removed in the future. A new package, py-melissa-online, has been added to the main spack repository. --- ## [New Melissa V3 released!](https://melissa.discourse.group/t/new-melissa-v3-released/63)
**Author:** [@AbhishekP](https://melissa.discourse.group/u/AbhishekP)\ **Replies:** 0\ **Last updated:** [August 5, 2026, 6:05pm UTC](https://melissa.discourse.group/t/new-melissa-v3-released/63 "2026-08-05T18:05:48Z")
--- ## [Active learning with Melissa](https://melissa.discourse.group/t/active-learning-with-melissa/62)
**Author:** [@bruno.raffin](https://melissa.discourse.group/u/bruno.raffin)\ **Replies:** 0\ **Last updated:** [June 11, 2026, 8:22am UTC](https://melissa.discourse.group/t/active-learning-with-melissa/62 "2026-06-11T08:22:16Z")
Preprint: Learning Where to Simulate: Generative Active Sampling for Online PDE Surrogate Training Latest Melissa related paper available on Arxiv: \[2606.09949\] Learning Where to Simulate: Generative Active Sampling for… --- ## [Policy-based Buffering](https://melissa.discourse.group/t/policy-based-buffering/61)
**Author:** [@AbhishekP](https://melissa.discourse.group/u/AbhishekP)\ **Replies:** 0\ **Last updated:** [April 7, 2026, 3:54pm UTC](https://melissa.discourse.group/t/policy-based-buffering/61 "2026-04-07T15:54:53Z")
The buffering hierarchy has been changed from using MixIn class to more robust policy based approach. This allows for more customization and have the ability to add different buffer easily based on user’s needs. More de… --- ## [Nix (flake) Installations now supported](https://melissa.discourse.group/t/nix-flake-installations-now-supported/60)
**Author:** [@AbhishekP](https://melissa.discourse.group/u/AbhishekP)\ **Replies:** 0\ **Last updated:** [March 18, 2026, 5:55pm UTC](https://melissa.discourse.group/t/nix-flake-installations-now-supported/60 "2026-03-18T17:55:32Z")
Melissa now provides Nix flake based support: Installation - --- ## [Melissa Develop now supports scikit-build-core based installations](https://melissa.discourse.group/t/melissa-develop-now-supports-scikit-build-core-based-installations/59)
**Author:** [@AbhishekP](https://melissa.discourse.group/u/AbhishekP)\ **Replies:** 0\ **Last updated:** [February 16, 2026, 3:03pm UTC](https://melissa.discourse.group/t/melissa-develop-now-supports-scikit-build-core-based-installations/59 "2026-02-16T15:03:06Z")
For more details, see the documentation: --- ## [Melissa will support multi version documentation v2.4.0 onwards](https://melissa.discourse.group/t/melissa-will-support-multi-version-documentation-v2-4-0-onwards/58)
**Author:** [@AbhishekP](https://melissa.discourse.group/u/AbhishekP)\ **Replies:** 0\ **Last updated:** [February 16, 2026, 1:49pm UTC](https://melissa.discourse.group/t/melissa-will-support-multi-version-documentation-v2-4-0-onwards/58 "2026-02-16T13:49:32Z")
https://melissa.gitlabpages.inria.fr/melissa/latest/ --- ## [New version v2.3.0 is out](https://melissa.discourse.group/t/new-version-v2-3-0-is-out/57)
**Author:** [@AbhishekP](https://melissa.discourse.group/u/AbhishekP)\ **Replies:** 0\ **Last updated:** [January 13, 2026, 2:15pm UTC](https://melissa.discourse.group/t/new-version-v2-3-0-is-out/57 "2026-01-13T14:15:09Z")
--- ## [New Simulation-paired Reservoir pre-released!](https://melissa.discourse.group/t/new-simulation-paired-reservoir-pre-released/56)
**Author:** [@AbhishekP](https://melissa.discourse.group/u/AbhishekP)\ **Replies:** 0\ **Last updated:** [October 21, 2025, 12:15pm UTC](https://melissa.discourse.group/t/new-simulation-paired-reservoir-pre-released/56 "2025-10-21T12:15:18Z")
Main Updates These updates are related to the new reservoir implementation that accommodates the foundational model training such as: ScOT: An All-to-All Architecture with no conditioning other than input time PDE-Tran… --- ## [Spack updates \`melissa\` and \`py-melissa-core\`](https://melissa.discourse.group/t/spack-updates-melissa-and-py-melissa-core/55)
**Author:** [@AbhishekP](https://melissa.discourse.group/u/AbhishekP)\ **Replies:** 0\ **Last updated:** [October 15, 2025, 11:16am UTC](https://melissa.discourse.group/t/spack-updates-melissa-and-py-melissa-core/55 "2025-10-15T11:16:20Z")
New versions are now available on spack py-melissa-core melissa --- ## [New v2.2.0 is Out](https://melissa.discourse.group/t/new-v2-2-0-is-out/54)
**Author:** [@AbhishekP](https://melissa.discourse.group/u/AbhishekP)\ **Replies:** 0\ **Last updated:** [September 19, 2025, 10:15am UTC](https://melissa.discourse.group/t/new-v2-2-0-is-out/54 "2025-09-19T10:15:53Z")
v2.2.0 Updates Fortran → C Client API Fixed melissa\_init with correct MPI\_Comm conversion. Exception Handling Fixed workflow and propagation of exceptions. ZeroMQ Client-Side Optimizations Added throttling… --- ## [Client API refactored in v2.1.0](https://melissa.discourse.group/t/client-api-refactored-in-v2-1-0/53)
**Author:** [@AbhishekP](https://melissa.discourse.group/u/AbhishekP)\ **Replies:** 2\ **Last updated:** [August 5, 2025, 2:03pm UTC](https://melissa.discourse.group/t/client-api-refactored-in-v2-1-0/53 "2025-08-05T14:03:18Z")
Summary This release focuses on simplifying the codebase, improving communication semantics, and removing outdated or unused components in preparation for further modularization and modernization. :white\_check\_mark: Wh… --- ## [New patch is out v2.0.1](https://melissa.discourse.group/t/new-patch-is-out-v2-0-1/52)
**Author:** [@AbhishekP](https://melissa.discourse.group/u/AbhishekP)\ **Replies:** 0\ **Last updated:** [July 21, 2025, 9:32am UTC](https://melissa.discourse.group/t/new-patch-is-out-v2-0-1/52 "2025-07-21T09:32:12Z")
General CMake added RPATHs for libzmq and mpi to be linked with libmelissa\_api.so. (This issue arised when working in a spack environment where manual install of melissa, although, successful, failed to link these to li… --- ## [Melissa v2.0.0 spack packages are now available](https://melissa.discourse.group/t/melissa-v2-0-0-spack-packages-are-now-available/51)
**Author:** [@AbhishekP](https://melissa.discourse.group/u/AbhishekP)\ **Replies:** 0\ **Last updated:** [June 26, 2025, 10:41am UTC](https://melissa.discourse.group/t/melissa-v2-0-0-spack-packages-are-now-available/51 "2025-06-26T10:41:02Z")
Following packages are now available for installation: py-melissa-core: Spack Packages melissa: Spack Packages To install, follow the instructions from Melissa’s documentation here: Installation - MELISSA --- ## [New Version is Out!](https://melissa.discourse.group/t/new-version-is-out/49)
**Author:** [@AbhishekP](https://melissa.discourse.group/u/AbhishekP)\ **Replies:** 0\ **Last updated:** [June 17, 2025, 9:55am UTC](https://melissa.discourse.group/t/new-version-is-out/49 "2025-06-17T09:55:03Z")
Release Notes for Melissa v2.0.0 Code Quality & Refactoring Added docstrings to all major files in melissa/. Added a .nix/ folder containing files to spawn a nix devshell for quick Melissa testing. Refactored multiple c… --- ## [Melissa's new quick setup using Nix](https://melissa.discourse.group/t/melissas-new-quick-setup-using-nix/48)
**Author:** [@AbhishekP](https://melissa.discourse.group/u/AbhishekP)\ **Replies:** 0\ **Last updated:** [June 11, 2025, 1:20pm UTC](https://melissa.discourse.group/t/melissas-new-quick-setup-using-nix/48 "2025-06-11T13:20:11Z")
Testing Melissa within Nix Overview The .nix/default.nix file provides a Nix shell or build environment for development. This is the quickest way to test Melissa Study locally. Note: These Nix files do not provide any G… --- ## [DL Interface improved](https://melissa.discourse.group/t/dl-interface-improved/47)
**Author:** [@AbhishekP](https://melissa.discourse.group/u/AbhishekP)\ **Replies:** 0\ **Last updated:** [March 10, 2025, 10:02pm UTC](https://melissa.discourse.group/t/dl-interface-improved/47 "2025-03-10T22:02:37Z")
DL interface for training has been improved and resembles more pytorch-lightning-ish API. Thus, improving readability and eas-of-use for users Check below links for more details: How to build a server Melissa Ser… --- ## [Melissa documentation update](https://melissa.discourse.group/t/melissa-documentation-update/46)
**Author:** [@AbhishekP](https://melissa.discourse.group/u/AbhishekP)\ **Replies:** 0\ **Last updated:** [March 10, 2025, 9:56pm UTC](https://melissa.discourse.group/t/melissa-documentation-update/46 "2025-03-10T21:56:13Z")
Entire documentation has been refactored and modified to the latest Melissa code. --- ## [Iterative statistics updated](https://melissa.discourse.group/t/iterative-statistics-updated/44)
**Author:** [@AbhishekP](https://melissa.discourse.group/u/AbhishekP)\ **Replies:** 1\ **Last updated:** [February 12, 2025, 10:42am UTC](https://melissa.discourse.group/t/iterative-statistics-updated/44 "2025-02-12T10:42:27Z")
New version of iterative statistics has been published (v0.1.1) The only changes that take place are, added automatic version bumping which updates all the files with the desired version. adjusted python support for t… --- ## [Melissa Server Refactored](https://melissa.discourse.group/t/melissa-server-refactored/43)
**Author:** [@AbhishekP](https://melissa.discourse.group/u/AbhishekP)\ **Replies:** 0\ **Last updated:** [February 3, 2025, 10:57am UTC](https://melissa.discourse.group/t/melissa-server-refactored/43 "2025-02-03T10:57:54Z")
Melissa server code has been refactored. The latest changes are merged into develop branch. Now, the usage of Melissa has become easier. Improvements/Adjustments to the hosted documentation are in progress. These new c… --- ## [Melissa API and function documentation](https://melissa.discourse.group/t/melissa-api-and-function-documentation/42)
**Author:** [@AbhishekP](https://melissa.discourse.group/u/AbhishekP)\ **Replies:** 0\ **Last updated:** [December 2, 2024, 6:47pm UTC](https://melissa.discourse.group/t/melissa-api-and-function-documentation/42 "2024-12-02T18:47:31Z")
Melissa API & function documentation is published: MELISSA --- ## [Sobol results changes for server ranks \> 0 (Develop Branch)](https://melissa.discourse.group/t/sobol-results-changes-for-server-ranks-0-develop-branch/39)
**Author:** [@AbhishekP](https://melissa.discourse.group/u/AbhishekP)\ **Replies:** 2\ **Last updated:** [October 10, 2024, 8:56am UTC](https://melissa.discourse.group/t/sobol-results-changes-for-server-ranks-0-develop-branch/39 "2024-10-10T08:56:08Z")
I am testing the main branch (ZMQ) with SA for result consistency when we change the server ranks. Below you will find that the results do not change in case of non-sobol runs while the sobol error increases proportional… --- ## [Adios integration](https://melissa.discourse.group/t/adios-integration/31)
**Author:** [@rob](https://melissa.discourse.group/u/rob)\ **Replies:** 4\ **Last updated:** [September 23, 2024, 9:46am UTC](https://melissa.discourse.group/t/adios-integration/31 "2024-09-23T09:46:13Z")
Hey everyone! We are experimenting with the replacement of ZMQ with Adios2 for the API. Our goals include: increase speed (leverage infiniband network) increase data transit flexibility (changing sizes, types etc) eas… --- ## [Slides: Melissa for Deep surrogate training explained](https://melissa.discourse.group/t/slides-melissa-for-deep-surrogate-training-explained/40)
**Author:** [@bruno.raffin](https://melissa.discourse.group/u/bruno.raffin)\ **Replies:** 0\ **Last updated:** [August 27, 2024, 12:54pm UTC](https://melissa.discourse.group/t/slides-melissa-for-deep-surrogate-training-explained/40 "2024-08-27T12:54:56Z")
Hello, Here are the slides I presented at Want@ICML24. Make a nice summary of Melissa approach to online surrogate training: Enjoy, Bruno --- ## [Statistical differences noticed from ZMQ -\> ADIOS2](https://melissa.discourse.group/t/statistical-differences-noticed-from-zmq-adios2/38)
**Author:** [@AbhishekP](https://melissa.discourse.group/u/AbhishekP)\ **Replies:** 3\ **Last updated:** [May 9, 2024, 5:21pm UTC](https://melissa.discourse.group/t/statistical-differences-noticed-from-zmq-adios2/38 "2024-05-09T17:21:12Z")
ADIOS2 repo has been updated for sobol’ indices computation. For the time being, we cache all the numpy arrays received from independent writers and then stack them together before sobol computations. I have noticed a f… --- ## [Strange behaviour of Adios with mpirun (when group size \> 1 for sobol)](https://melissa.discourse.group/t/strange-behaviour-of-adios-with-mpirun-when-group-size-1-for-sobol/37)
**Author:** [@AbhishekP](https://melissa.discourse.group/u/AbhishekP)\ **Replies:** 0\ **Last updated:** [April 4, 2024, 3:17pm UTC](https://melissa.discourse.group/t/strange-behaviour-of-adios-with-mpirun-when-group-size-1-for-sobol/37 "2024-04-04T15:17:55Z")
Hi folks, I am currently working on implementing Adios with sobol. As our Adios writers are sending the data independently we can do the grouping and then compute the sobol’ indices. But before jumping on the actual cod… --- ## [OAR fails with deep learning heat-pde example](https://melissa.discourse.group/t/oar-fails-with-deep-learning-heat-pde-example/36)
**Author:** [@AbhishekP](https://melissa.discourse.group/u/AbhishekP)\ **Replies:** 4\ **Last updated:** [March 11, 2024, 12:24pm UTC](https://melissa.discourse.group/t/oar-fails-with-deep-learning-heat-pde-example/36 "2024-03-11T12:24:21Z")
Hello @rob I did a fresh install of melissa as per the documentation on G5K and the binaries are generated ~/.local/. I was able to obtain the results for Sensitivity Analysis example using config\_oar.json However, whe… --- ## [Melissa Virtual Cluster Issues](https://melissa.discourse.group/t/melissa-virtual-cluster-issues/35)
**Author:** [@AbhishekP](https://melissa.discourse.group/u/AbhishekP)\ **Replies:** 2\ **Last updated:** [March 5, 2024, 9:34am UTC](https://melissa.discourse.group/t/melissa-virtual-cluster-issues/35 "2024-03-05T09:34:16Z")
Hey @rob, Issues with the commit Firstly, I went on your commit and after running the build-and-install.sh script, I get the following errors. Building and installing gitlab-runner in virtual cluster temp- Error: Faile… --- ## [Melissa Guix Packages in Guix-HPC Channel](https://melissa.discourse.group/t/melissa-guix-packages-in-guix-hpc-channel/33)
**Author:** [@bruno.raffin](https://melissa.discourse.group/u/bruno.raffin)\ **Replies:** 0\ **Last updated:** [January 11, 2024, 11:01am UTC](https://melissa.discourse.group/t/melissa-guix-packages-in-guix-hpc-channel/33 "2024-01-11T11:01:47Z")
An improved version of the guix packages for melissa (sensibility analysis) is now integrated in the Guix-HPC channel thanks to Romain and Ludovic (guix-hpc / Guix-HPC · GitLab). [Next page](https://melissa.discourse.group/latest.md?page=1)