MPI_T_CVAR_HANDLE_ALLOC(3)

💖 NAME 💖

MPI_T_cvar_handle_alloc, MPI_T_cvar_handle_free — allocate/free control variable handles

okay bestie, welcome to the Open MPI manual page for MPI_T_CVAR_HANDLE_ALLOC(3) 💅 this is the one that hands you a handle to a control variable so you can actually poke at it. two functions, one page, let's go ✨

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🦋 SYNTAX 🦋

🌸 C Syntax 🌸

#include <mpi.h>

int MPI_T_cvar_handle_alloc(int cvar_index, void *obj_handle,
                            MPI_T_cvar_handle *handle, int *count)

int MPI_T_cvar_handle_free(MPI_T_cvar_handle *handle)

that's it, that's the whole vibe. include mpi.h and you're set 🫶

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✨ DESCRIPTION ✨

MPI_T_cvar_handle_alloc takes the control variable you named in cvar_index and binds it to the MPI object you named in obj_handle. cute, right?

but here's the tea 🍓 — if MPI_T_cvar_get_info hands back MPI_T_BIND_NO_OBJECT as the binding of that variable, then the obj_handle argument is just... ignored. not even looked at. literally doesn't matter what you put there.

the number of values this control variable represents gets returned in the count parameter. and if the control variable is a string, then count is the maximum length of the string. don't forget that part, it's giving important 💀

MPI_T_cvar_handle_free does exactly what it says on the tin: it frees a handle that MPI_T_cvar_handle_alloc allocated, and sets the handle argument to MPI_T_CVAR_HANDLE_NULL. clean exit, no crumbs left behind 🧹✨

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👑 NOTES 👑

Open MPI does not currently support binding MPI objects to control variables, so the obj_handle argument is always ignored.

no cap. so in Open MPI land, that parameter is decorative 😭🙈

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💀 ERRORS 💀

MPI_T_cvar_handle_alloc will fail if:

• MPI_T_ERR_NOT_INITIALIZED: The MPI Tools interface not initialized
• MPI_T_ERR_INVALID_INDEX: The control variable index is invalid
• MPI_T_ERR_OUT_OF_HANDLES: No more handles available

MPI_T_cvar_handle_free will fail if:

• MPI_T_ERR_NOT_INITIALIZED: The MPI Tools interface not initialized
• MPI_T_ERR_INVALID_HANDLE: The handle is invalid

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🌈 SEE ALSO 🌈

• MPI_T_cvar_get_info 👀 (the one that tells you the binding, iykyk)

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🎀 Copyright 🎀

2003-2026, The Open MPI Community

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and that's a wrap, bestie 🦋✨ this was MPI_T_CVAR_HANDLE_ALLOC(3) from Open MPI, dated Sep 10, 2026 — go forth and handle your control variables responsibly 💖🌸🫶