MPI_FILE_GET_SIZE(3)

💅 MPI_FILE_GET_SIZE(3) — Open MPI girlies rise

okay so bestie, this is a page from Open MPI, manual section 3, and it's literally all about MPI_File_get_size 🎀 — aka "how big is my file actually." Let's get into it.

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✨ NAME ✨

MPI_File_get_size — returns the current size of the file. that's it. that's the whole gig 💖

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🦋 SYNTAX 🦋

C Syntax

#include <mpi.h>

int MPI_File_get_size(MPI_File fh, MPI_Offset *size)

Fortran Syntax

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_FILE_GET_SIZE(FH, SIZE, IERROR)
     INTEGER FH, ERROR
     INTEGER(KIND=MPI_OFFSET_KIND)   SIZE

Fortran 2008 Syntax

USE mpi_f08
MPI_File_get_size(fh, size, ierror)
     TYPE(MPI_File), INTENT(IN) :: fh
     INTEGER(KIND=MPI_OFFSET_KIND), INTENT(OUT) :: size
     INTEGER, OPTIONAL, INTENT(OUT) :: ierror

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🌸 INPUT PARAMETERS 🌸

• fh — the file handle, aka your little passport to the file (handle). 🫶
• size — size of the file in bytes (integer). yes it's listed under input parameters in the original, we don't question the vibe check, we just report it 💅

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⭐ OUTPUT PARAMETER ⭐

• ierror — Fortran only: the error status (integer). she's optional in the mpi_f08 version, iconic behavior 💜

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🌈 DESCRIPTION 🌈

So MPI_File_get_size returns, in size, the current size in bytes of the file associated with the file handle fh. simple. clean. slay. ✨

⚠️ but wait — one crucial note: the file size returned by Solaris may not represent the number of bytes physically allocated for the file, specifically in those cases where all the bytes in the file haven't been written at least once. so like... don't come for Solaris when it tells you a number you weren't expecting, okay? 😭 it's a known thing.

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💀 ERRORS 💀

okay bestie this is the long part, but it matters so stay with me 🫶

Almost all MPI routines return an error value; C routines as the return result of the function, and Fortran routines in the last argument. fr fr.

Before the error value is returned, the current MPI error handler associated with the communication object (e.g., communicator, window, file) is called. If no communication object is associated with the MPI call, then the call is considered attached to MPI_COMM_SELF and will call the associated MPI error handler. When MPI_COMM_SELF is not initialized (i.e., before MPI_Init/MPI_Init_thread, after MPI_Finalize, or when using the Sessions Model exclusively) the error raises the initial error handler. The initial error handler can be changed by calling MPI_Comm_set_errhandler on MPI_COMM_SELF when using the World model, or the mpi_initial_errhandler CLI argument to mpiexec or info key to MPI_Comm_spawn/MPI_Comm_spawn_multiple. If no other appropriate error handler has been set, then the MPI_ERRORS_RETURN error handler is called for MPI I/O functions and the MPI_ERRORS_ABORT error handler is called for all other MPI functions. 👑

Open MPI includes three predefined error handlers that can be used:

• MPI_ERRORS_ARE_FATAL — causes the program to abort all connected MPI processes. yeah. everybody. gone. 💀
• MPI_ERRORS_ABORT — an error handler that can be invoked on a communicator, window, file, or session. When called on a communicator, it acts as if MPI_Abort was called on that communicator. If called on a window or file, it acts as if MPI_Abort was called on a communicator containing the group of processes in the corresponding window or file. If called on a session, it aborts only the local process. nuance! we love her 🎀
• MPI_ERRORS_RETURN — returns an error code to the application. the chill one. the "here you go, handle it yourself" one 🫶

MPI applications can also implement their own error handlers by calling:

• MPI_Comm_create_errhandler then MPI_Comm_set_errhandler
• MPI_File_create_errhandler then MPI_File_set_errhandler
• MPI_Session_create_errhandler then MPI_Session_set_errhandler or at MPI_Session_init
• MPI_Win_create_errhandler then MPI_Win_set_errhandler

😭 important caveat bestie: note that MPI does not guarantee that an MPI program can continue past an error. so like, don't assume you can just pick yourself up and keep going. no cap.

See the MPI man page for a full list of MPI error codes.

See the Error Handling section of the MPI-3.1 standard for more information.

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🔥 SEE ALSO 🔥

• MPI_File_preallocate — go read that one next, she's the prequel ✨

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👑 COPYRIGHT 👑

2003-2026, The Open MPI Community — legends, all of them. 💖

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okay that's the whole page, you ate that 🍓 and just so we're keeping it a hundred: this was the Open MPI page for MPI_File_get_size(3), dated Sep 11, 2026 — mwah, go forth and check your file sizes responsibly 🧚‍♀️💅