Hi Martin, Unfortunately, singleton init is still not fixed in MPICH. There is a PR fixing it for `hydra2` -- https://github.com/pmodels/mpich/pull/3340. The fix for hydra would be similar. -- Hui Zhou From: Martín Morales via discuss <[email protected]> Reply-To: "[email protected]" <[email protected]> Date: Wednesday, April 29, 2020 at 4:22 PM To: "[email protected]" <[email protected]> Cc: Martín Morales <[email protected]> Subject: [mpich-discuss] Singleton spawns Hello All. I really need to run mi application like a singleton (i.e. without mpirun) and dynamically spawns tasks from there. I recently builded the last release (mpich 3.3.2), but I can't do this. So, the singleton spawns It's not supported or I'm doing something wrong? Thanks. Martín