Upgrade macos
This commit is contained in:
Bassem Girgis
@@ -1,183 +1,259 @@
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.\" -*- nroff -*-
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.\" Copyright 2006-2008 Sun Microsystems, Inc.
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.\" Copyright (c) 1996 Thinking Machines Corporation
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.\" Copyright (c) 2010-2015 Cisco Systems, Inc. All rights reserved.
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.\" $COPYRIGHT$
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.TH MPI_Init_thread 3 "Mar 26, 2019" "4.0.1" "Open MPI"
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.\" Man page generated from reStructuredText.
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.
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.SH NAME
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\fBMPI_Init_thread\fP \- Initializes the MPI execution environment
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.TH "MPI_INIT_THREAD" "3" "Feb 14, 2025" "" "Open MPI"
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.
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.nr rst2man-indent-level 0
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.
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.de1 rstReportMargin
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\\$1 \\n[an-margin]
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level margin: \\n[rst2man-indent\\n[rst2man-indent-level]]
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\\n[rst2man-indent1]
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\\n[rst2man-indent2]
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..
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.de1 INDENT
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.\" .rstReportMargin pre:
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. RS \\$1
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. nr rst2man-indent\\n[rst2man-indent-level] \\n[an-margin]
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. nr rst2man-indent-level +1
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.\" .rstReportMargin post:
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..
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.de UNINDENT
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. RE
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.\" indent \\n[an-margin]
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.\" old: \\n[rst2man-indent\\n[rst2man-indent-level]]
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.nr rst2man-indent-level -1
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.\" new: \\n[rst2man-indent\\n[rst2man-indent-level]]
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.in \\n[rst2man-indent\\n[rst2man-indent-level]]u
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..
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.sp
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\fI\%MPI_Init_thread\fP — Initializes the MPI execution environment
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.SH SYNTAX
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.ft R
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.
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.SH C Syntax
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.SS C Syntax
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.INDENT 0.0
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.INDENT 3.5
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.sp
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.nf
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.ft C
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#include <mpi.h>
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int MPI_Init_thread(int *\fIargc\fP, char ***\fIargv\fP,
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int \fIrequired\fP, int *\fIprovided\fP)
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int MPI_Init_thread(int *argc, char ***argv,
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int required, int *provided)
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.ft P
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.fi
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.SH INPUT PARAMETERS
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.ft R
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.TP 1i
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argc
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C/C++ only: Pointer to the number of arguments.
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.TP 1i
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argv
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C/C++ only: Argument vector.
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.TP 1i
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required
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Desired level of thread support (integer).
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.
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.
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.SH OUTPUT PARAMETERS
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.ft R
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.TP 1i
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provided
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Available level of thread support (integer).
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.TP 1i
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IERROR
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Fortran only: Error status (integer).
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.
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.
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.SH DESCRIPTION
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.ft R
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This routine, or MPI_Init, must be called before most other MPI
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routines are called. There are a small number of exceptions, such as
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MPI_Initialized and MPI_Finalized. MPI can be initialized at most
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once; subsequent calls to MPI_Init or MPI_Init_thread are erroneous.
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.sp
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MPI_Init_thread, as compared to MPI_Init, has a provision to request a
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certain level of thread support in \fIrequired\fP:
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.TP 2.4i
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MPI_THREAD_SINGLE
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Only one thread will execute.
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.TP 2.4i
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MPI_THREAD_FUNNELED
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If the process is multithreaded, only the thread that called
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MPI_Init_thread will make MPI calls.
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.TP 2.4i
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MPI_THREAD_SERIALIZED
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If the process is multithreaded, only one thread will make MPI library
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calls at one time.
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.TP 2.4i
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MPI_THREAD_MULTIPLE
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If the process is multithreaded, multiple threads may call MPI at once
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with no restrictions.
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.
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.PP
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The level of thread support available to the program is set in
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\fIprovided\fP, except in C++, where it is the return value of the
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function. In Open MPI, the value is dependent on how the library was
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configured and built. Note that there is no guarantee that
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\fIprovided\fP will be greater than or equal to \fIrequired\fP.
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.sp
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Also note that calling MPI_Init_thread with a
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.I required
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value of
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.I MPI_THREAD_SINGLE
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is equivalent to calling MPI_Init.
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.sp
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All MPI programs must contain a call to MPI_Init or
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MPI_Init_thread. Open MPI accepts the C/C++ \fIargc\fP and \fIargv\fP
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arguments to main, but neither modifies, interprets, nor distributes
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them:
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.UNINDENT
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.UNINDENT
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.SS Fortran Syntax
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.INDENT 0.0
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.INDENT 3.5
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.sp
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.nf
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{
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/* declare variables */
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MPI_Init_thread(&argc, &argv, req, &prov);
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/* parse arguments */
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/* main program */
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MPI_Finalize();
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}
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.ft C
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USE MPI
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! or the older form: INCLUDE \(aqmpif.h\(aq
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MPI_INIT_THREAD(REQUIRED, PROVIDED, IERROR)
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INTEGER REQUIRED, PROVIDED, IERROR
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.ft P
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.fi
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.
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.SH NOTES
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.ft R
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The Fortran version does not have provisions for \fIargc\fP and
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\fIargv\fP and takes only IERROR.
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.UNINDENT
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.UNINDENT
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.SS Fortran 2008 Syntax
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.INDENT 0.0
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.INDENT 3.5
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.sp
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It is the caller's responsibility to check the value of \fIprovided\fP,
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as it may be less than what was requested in \fIrequired\fP.
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.nf
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.ft C
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USE mpi_f08
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MPI_Init_thread(required, provided, ierror)
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INTEGER, INTENT(IN) :: required
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INTEGER, INTENT(OUT) :: provided
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INTEGER, OPTIONAL, INTENT(OUT) :: ierror
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.ft P
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.fi
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.UNINDENT
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.UNINDENT
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.SH INPUT PARAMETERS
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.INDENT 0.0
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.IP \(bu 2
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\fBargc\fP: C only: Pointer to the number of arguments.
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.IP \(bu 2
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\fBargv\fP: C only: Argument vector.
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.IP \(bu 2
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\fBrequired\fP: Desired level of thread support (integer).
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.UNINDENT
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.SH OUTPUT PARAMETERS
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.INDENT 0.0
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.IP \(bu 2
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\fBprovided\fP: Available level of thread support (integer).
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.IP \(bu 2
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\fBierror\fP: Fortran only: Error status (integer).
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.UNINDENT
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.SH DESCRIPTION
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.sp
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This routine, or \fI\%MPI_Init\fP, must be called before most other MPI routines
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are called. There are a small number of exceptions, such as
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\fI\%MPI_Initialized\fP and \fI\%MPI_Finalized\fP\&. MPI can be initialized at most once;
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subsequent calls to \fI\%MPI_Init\fP or \fI\%MPI_Init_thread\fP are erroneous.
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.sp
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\fI\%MPI_Init_thread\fP, as compared to \fI\%MPI_Init\fP, has a provision to request a
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certain level of thread support in \fIrequired\fP:
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.INDENT 0.0
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.TP
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.B MPI_THREAD_SINGLE
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Only one thread will execute.
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.TP
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.B MPI_THREAD_FUNNELED
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If the process is multithreaded, only the thread that called
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\fI\%MPI_Init_thread\fP will make MPI calls.
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.TP
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.B MPI_THREAD_SERIALIZED
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If the process is multithreaded, only one thread will make MPI
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library calls at one time.
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.TP
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.B MPI_THREAD_MULTIPLE
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If the process is multithreaded, multiple threads may call MPI at
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once with no restrictions.
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.UNINDENT
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.sp
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The level of thread support available to the program is set in
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\fIprovided\fP\&. In Open MPI, the value is dependent on how the library was
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configured and built. Note that there is no guarantee that \fIprovided\fP
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will be greater than or equal to \fIrequired\fP\&.
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.sp
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Also note that calling \fI\%MPI_Init_thread\fP with a \fIrequired\fP value of
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MPI_THREAD_SINGLE is equivalent to calling \fI\%MPI_Init\fP\&.
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.sp
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All MPI programs must contain a call to \fI\%MPI_Init\fP or \fI\%MPI_Init_thread\fP\&.
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Open MPI accepts the C \fIargc\fP and \fIargv\fP arguments to main, but neither
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modifies, interprets, nor distributes them:
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.INDENT 0.0
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.INDENT 3.5
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.sp
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.nf
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.ft C
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/* declare variables */
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MPI_Init_thread(&argc, &argv, req, &prov);
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/* parse arguments */
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/* main program */
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MPI_Finalize();
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.ft P
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.fi
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.UNINDENT
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.UNINDENT
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.SH NOTES
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.sp
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The Fortran version does not have provisions for \fBargc\fP and \fBargv\fP and
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takes only \fBIERROR\fP\&.
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.sp
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It is the caller’s responsibility to check the value of \fBprovided\fP, as
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it may be less than what was requested in \fBrequired\fP\&.
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.sp
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The MPI Standard does not say what a program can do before an
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MPI_Init_thread or after an MPI_Finalize. In the Open MPI
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implementation, it should do as little as possible. In particular,
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avoid anything that changes the external state of the program, such as
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opening files, reading standard input, or writing to standard output.
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.
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.
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.SH MPI_THREAD_MULTIPLE Support
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.
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MPI_THREAD_MULTIPLE support is included if Open MPI was configured
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with the --enable-mpi-thread-multiple configure switch. You can check the
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output of
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.BR ompi_info (1)
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to see if Open MPI has MPI_THREAD_MULTIPLE support:
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.
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.PP
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.nf
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shell$ ompi_info | grep -i thread
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Thread support: posix (mpi: yes, progress: no)
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shell$
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.fi
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.
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.PP
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The "mpi: yes" portion of the above output indicates that Open MPI was
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compiled with MPI_THREAD_MULTIPLE support.
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.
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.PP
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Note that MPI_THREAD_MULTIPLE support is only lightly tested. It
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likely does not work for thread-intensive applications. Also note
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that
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.I only
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the MPI point-to-point communication functions for the BTL's listed
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below are considered thread safe. Other support functions (e.g., MPI
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attributes) have not been certified as safe when simultaneously used
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by multiple threads.
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.
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.PP
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.nf
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tcp
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sm
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mx
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elan
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self
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.fi
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.
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.PP
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Note that Open MPI's thread support is in a fairly early stage; the
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above devices are likely to
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.IR work ,
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but the latency is likely to be fairly high. Specifically, efforts so
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far have concentrated on
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.IR correctness ,
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not
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.I performance
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(yet).
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.
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.
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.SH ERRORS
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.ft R
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Almost all MPI routines return an error value; C routines as
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the value of the function and Fortran routines in the last argument. C++
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functions do not return errors. If the default error handler is set to
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MPI::ERRORS_THROW_EXCEPTIONS, then on error the C++ exception mechanism
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will be used to throw an MPI::Exception object.
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\fI\%MPI_Init_thread\fP or after an \fI\%MPI_Finalize\fP\&. In the Open MPI
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implementation, it should do as little as possible. In particular, avoid
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anything that changes the external state of the program, such as opening
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files, reading standard input, or writing to standard output.
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.SS MPI_THREAD_MULTIPLE Support
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.sp
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\fBMPI_THREAD_MULTIPLE\fP support is included if the environment in which
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Open MPI was built supports threading. You can check the output of
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\fI\%ompi_info(1)\fP to see if Open MPI has
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\fBMPI_THREAD_MULTIPLE\fP support:
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.INDENT 0.0
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.INDENT 3.5
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.sp
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Before the error value is returned, the current MPI error handler is
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called. By default, this error handler aborts the MPI job, except for
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I/O function errors. The error handler may be changed with
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MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN
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may be used to cause error values to be returned. Note that MPI does not
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guarantee that an MPI program can continue past an error.
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.
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.SH SEE ALSO
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.ft R
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.nf
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MPI_Init
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MPI_Initialized
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MPI_Finalize
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MPI_Finalized
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.ft C
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shell$ ompi_info | grep "Thread support"
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Thread support: posix (MPI_THREAD_MULTIPLE: yes, OPAL support: yes, OMPI progress: no, Event lib: yes)
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shell$
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.ft P
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.fi
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.UNINDENT
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.UNINDENT
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.sp
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The \fBMPI_THREAD_MULTIPLE: yes\fP portion of the above output indicates
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that Open MPI was compiled with \fBMPI_THREAD_MULTIPLE\fP support.
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.sp
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Note that there is a small performance penalty for using
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\fBMPI_THREAD_MULTIPLE\fP support; latencies for short messages will be higher
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as compared to when using \fBMPI_THREAD_SINGLE\fP, for example.
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.SH ERRORS
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.sp
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Almost all MPI routines return an error value; C routines as the return result
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of the function and Fortran routines in the last argument.
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.sp
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Before the error value is returned, the current MPI error handler associated
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with the communication object (e.g., communicator, window, file) is called.
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If no communication object is associated with the MPI call, then the call is
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considered attached to MPI_COMM_SELF and will call the associated MPI error
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handler. When MPI_COMM_SELF is not initialized (i.e., before
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\fI\%MPI_Init\fP/\fI\%MPI_Init_thread\fP, after \fI\%MPI_Finalize\fP, or when using the Sessions
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Model exclusively) the error raises the initial error handler. The initial
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error handler can be changed by calling \fI\%MPI_Comm_set_errhandler\fP on
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MPI_COMM_SELF when using the World model, or the mpi_initial_errhandler CLI
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argument to mpiexec or info key to \fI\%MPI_Comm_spawn\fP/\fI\%MPI_Comm_spawn_multiple\fP\&.
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If no other appropriate error handler has been set, then the MPI_ERRORS_RETURN
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error handler is called for MPI I/O functions and the MPI_ERRORS_ABORT error
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handler is called for all other MPI functions.
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.sp
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Open MPI includes three predefined error handlers that can be used:
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.INDENT 0.0
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.IP \(bu 2
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||||
\fBMPI_ERRORS_ARE_FATAL\fP
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||||
Causes the program to abort all connected MPI processes.
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||||
.IP \(bu 2
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||||
\fBMPI_ERRORS_ABORT\fP
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||||
An error handler that can be invoked on a communicator,
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||||
window, file, or session. When called on a communicator, it
|
||||
acts as if \fI\%MPI_Abort\fP was called on that communicator. If
|
||||
called on a window or file, acts as if \fI\%MPI_Abort\fP was called
|
||||
on a communicator containing the group of processes in the
|
||||
corresponding window or file. If called on a session,
|
||||
aborts only the local process.
|
||||
.IP \(bu 2
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||||
\fBMPI_ERRORS_RETURN\fP
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||||
Returns an error code to the application.
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||||
.UNINDENT
|
||||
.sp
|
||||
MPI applications can also implement their own error handlers by calling:
|
||||
.INDENT 0.0
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||||
.IP \(bu 2
|
||||
\fI\%MPI_Comm_create_errhandler\fP then \fI\%MPI_Comm_set_errhandler\fP
|
||||
.IP \(bu 2
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||||
\fI\%MPI_File_create_errhandler\fP then \fI\%MPI_File_set_errhandler\fP
|
||||
.IP \(bu 2
|
||||
\fI\%MPI_Session_create_errhandler\fP then \fI\%MPI_Session_set_errhandler\fP or at \fI\%MPI_Session_init\fP
|
||||
.IP \(bu 2
|
||||
\fI\%MPI_Win_create_errhandler\fP then \fI\%MPI_Win_set_errhandler\fP
|
||||
.UNINDENT
|
||||
.sp
|
||||
Note that MPI does not guarantee that an MPI program can continue past
|
||||
an error.
|
||||
.sp
|
||||
See the \fI\%MPI man page\fP for a full list of \fI\%MPI error codes\fP\&.
|
||||
.sp
|
||||
See the Error Handling section of the MPI\-3.1 standard for
|
||||
more information.
|
||||
.sp
|
||||
\fBSEE ALSO:\fP
|
||||
.INDENT 0.0
|
||||
.INDENT 3.5
|
||||
.INDENT 0.0
|
||||
.IP \(bu 2
|
||||
\fI\%MPI_Init\fP
|
||||
.IP \(bu 2
|
||||
\fI\%MPI_Initialized\fP
|
||||
.IP \(bu 2
|
||||
\fI\%MPI_Finalize\fP
|
||||
.IP \(bu 2
|
||||
\fI\%MPI_Finalized\fP
|
||||
.UNINDENT
|
||||
.UNINDENT
|
||||
.UNINDENT
|
||||
.SH COPYRIGHT
|
||||
2003-2025, The Open MPI Community
|
||||
.\" Generated by docutils manpage writer.
|
||||
.
|
||||
|
||||
Reference in New Issue
Block a user