MPI_Comm_fromint(3)

💖 MPI_Comm_fromint — bestie's guide to turning an int into a communicator 💖

okay so this is a page from the MPI manual (yes, that MPI, the message-passing one, the one that makes your cluster go brrr), and today's main character is MPI_Comm_fromint. it's short. it's sweet. it's giving "tiny function, big responsibilities." let's get into it 🫶

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✨ NAME ✨

MPI_Comm_fromint — converts an integer handle to MPI_Comm

like. that's it. that's the whole job. you hand it a number, it hands you back a real live communicator. no cap. 💅

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🌸 SYNOPSIS 🌸

MPI_Comm MPI_Comm_fromint(int comm)

she's a one-liner, she's a legend, she's literally one function call. 😭

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🎀 INPUT PARAMETERS 🎀

• comm — comm (integer). yes bestie, it's an integer, that's the whole point of the function. you're the one who has to know whether that int actually means anything real. 🙈

I'm not gonna lie to you, the manpage does not elaborate further here and neither will I, because inventing extra lore would be a crime and I do not commit crimes against documentation. the original said "comm (integer)" and I said "comm (integer)". periodt.

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🦋 THREAD AND INTERRUPT SAFETY 🦋

good news first: this routine is thread-safe. 💖 that means you can hit it from multiple threads at the same time and you do not need to set up any user-provided thread locks around it. she handles herself. main character energy fr fr.

okay and now the little caveat, because there's always one: the routine is not interrupt safe. 😭 typically this is because of memory allocation routines like malloc, or other non-MPICH runtime routines that are themselves not interrupt-safe. so like… thread-safe ✅, interrupt-safe ❌, and that distinction is load-bearing, do not skip it. 💀

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👑 that's the whole page 👑

not me writing a manpage review for a function that fits in one line. iconic behavior honestly. go forth and convert your integers. 🌈

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a lil sign-off from your girl: this page is from the MPI manual, it's the MPI_Comm_fromint(3) entry, and it was dated 4/10/2026. slay, take care of yourself, drink water, and please read the manpage before opening an issue bestie. ✨🍓💜