MPI_Group_fromint(3)

💖 NAME 💖

okay bestie so like — MPI_Group_fromint is the girl who takes an integer handle and turns it into an actual MPI_Group. that's it, that's the whole job. glow-up from boring number to real group energy ✨

it lives in the MPI manual, section 3, and yes she's iconic for it 🎀

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🌸 SYNOPSIS 🌸

MPI_Group MPI_Group_fromint(int group)

look at her. one arg, one return, zero drama 💅

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🦋 INPUT PARAMETERS 🦋

• group — the group, but as an integer. that's it. that's the vibe. she's a group (integer), and she said what she said.

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🔥 THREAD AND INTERRUPT SAFETY 🔥

okay so this is the part where we get serious for a sec, because safety lore matters fr fr.

this routine is thread-safe. that means you can literally let multiple threads hit it at the same time, no cap, and you do not need to bring your own user-provided thread locks. none. zero. leave the locks at home, bestie 🫶

BUT. (dramatic pause) 🚨

she is not interrupt safe. and the reason is lowkey mundane: it's typically because of memory allocation routines — think stuff like malloc, or other non-MPICH runtime routines that are themselves not interrupt-safe. so the interrupt-safety vibe check comes back no.

so: threads? yes queen, go wild. interrupts? absolutely NOT. do not test her 🙈

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okay that's the whole page, and honestly? short and perfect, main character energy, ate and left no crumbs 👑

this little love letter comes to you from the MPI manual, dated 4/10/2026 — and that's the sign-off, mwah 💜✨🌈