250 lines
8.4 KiB
Groff
250 lines
8.4 KiB
Groff
.\" Man page generated from reStructuredText.
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.TH "MPI_TESTSOME" "3" "Feb 14, 2025" "" "Open MPI"
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.sp
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\fI\%MPI_Testsome\fP — Tests for completion of one or more previously
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initiated communications in a list.
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.SH 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_Testsome(int incount, MPI_Request array_of_requests[],
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int *outcount, int array_of_indices[],
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MPI_Status array_of_statuses[])
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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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.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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.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_TESTSOME(INCOUNT, ARRAY_OF_REQUESTS, OUTCOUNT,
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ARRAY_OF_INDICES, ARRAY_OF_STATUSES, IERROR)
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INTEGER INCOUNT, ARRAY_OF_REQUESTS(*)
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INTEGER OUTCOUNT, ARRAY_OF_INDICES(*)
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INTEGER ARRAY_OF_STATUSES(MPI_STATUS_SIZE,*), 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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.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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.nf
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.ft C
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USE mpi_f08
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MPI_Testsome(incount, array_of_requests, outcount, array_of_indices,
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array_of_statuses, ierror)
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INTEGER, INTENT(IN) :: incount
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TYPE(MPI_Request), INTENT(INOUT) :: array_of_requests(incount)
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INTEGER, INTENT(OUT) :: outcount, array_of_indices(*)
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TYPE(MPI_Status) :: array_of_statuses(*)
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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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\fBincount\fP: Length of array_of_requests (integer).
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.IP \(bu 2
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\fBarray_of_requests\fP: Array of requests (array of handles).
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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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\fBoutcount\fP: Number of completed requests (integer).
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.IP \(bu 2
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\fBarray_of_indices\fP: Array of indices of operations that completed (array of integers).
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.IP \(bu 2
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\fBarray_of_statuses\fP: Array of status objects for operations that completed (array of status).
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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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Behaves like \fI\%MPI_Waitsome\fP, except that it returns immediately.
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.sp
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Returns in outcount the number of requests from the list
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array_of_requests that have completed. Returns in the first outcount
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locations of the array array_of_indices the indices of these operations
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(index within the array array_of_requests; the array is indexed from 0
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in C and from 1 in Fortran). Returns in the first outcount locations of
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the array array_of_status the status for these completed operations. If
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a request that completed was allocated by a nonblocking communication
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call, then it is deallocated, and the associated handle is set to
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MPI_REQUEST_NULL.
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.sp
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If no operation has completed it returns outcount = 0. If there is no
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active handle in the list, it returns outcount = MPI_UNDEFINED.
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.sp
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\fI\%MPI_Testsome\fP is a local operation, which returns immediately, whereas
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\fI\%MPI_Waitsome\fP blocks until a communication completes, if it was passed a
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list that contains at least one active handle. Both calls fulfill a
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fairness requirement: If a request for a receive repeatedly appears in a
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list of requests passed to \fI\%MPI_Waitsome\fP or \fI\%MPI_Testsome\fP, and a matching
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send has been posted, then the receive will eventually succeed unless
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the send is satisfied by another receive; send requests also fulfill
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this fairness requirement.
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.sp
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Errors that occur during the execution of \fI\%MPI_Testsome\fP are handled as
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for \fI\%MPI_Waitsome\fP\&.
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.sp
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If your application does not need to examine the \fIarray_of_statuses\fP
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field, you can save resources by using the predefined constant
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MPI_STATUSES_IGNORE can be used as a special value for the
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\fIarray_of_statuses\fP argument.
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.SH NOTES
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.sp
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The use of \fI\%MPI_Testsome\fP is likely to be more efficient than the use of
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\fI\%MPI_Testany\fP\&. The former returns information on all completed
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communications; with the latter, a new call is required for each
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communication that completes.
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.sp
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A server with multiple clients can use \fI\%MPI_Waitsome\fP so as not to starve
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any client. Clients send messages to the server with service requests.
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The server calls \fI\%MPI_Waitsome\fP with one receive request for each client,
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then handles all receives that have completed. If a call to \fI\%MPI_Waitany\fP
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is used instead, then one client could starve while requests from
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another client always sneak in first.
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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
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acts as if \fI\%MPI_Abort\fP was called on that communicator. If
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called on a window or file, acts as if \fI\%MPI_Abort\fP was called
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on a communicator containing the group of processes in the
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corresponding window or file. If called on a session,
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aborts only the local process.
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.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
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.sp
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MPI applications can also implement their own error handlers by calling:
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.INDENT 0.0
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.IP \(bu 2
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\fI\%MPI_Comm_create_errhandler\fP then \fI\%MPI_Comm_set_errhandler\fP
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.IP \(bu 2
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\fI\%MPI_File_create_errhandler\fP then \fI\%MPI_File_set_errhandler\fP
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.IP \(bu 2
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\fI\%MPI_Session_create_errhandler\fP then \fI\%MPI_Session_set_errhandler\fP or at \fI\%MPI_Session_init\fP
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.IP \(bu 2
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\fI\%MPI_Win_create_errhandler\fP then \fI\%MPI_Win_set_errhandler\fP
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.UNINDENT
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.sp
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Note that MPI does not guarantee that an MPI program can continue past
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an error.
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.sp
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See the \fI\%MPI man page\fP for a full list of \fI\%MPI error codes\fP\&.
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.sp
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See the Error Handling section of the MPI\-3.1 standard for
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more information.
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.sp
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For each invocation of \fI\%MPI_Testsome\fP, if one or more requests
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generate an MPI error, only the \fIfirst\fP MPI request that caused an
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error will be passed to its corresponding error handler. No other
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error handlers will be invoked (even if multiple requests generated
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errors). However, \fIall\fP requests that generate an error will have a
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relevant error code set in the corresponding \fBstatus.MPI_ERROR\fP
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field (unless \fBMPI_STATUSES_IGNORE\fP was used).
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.sp
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If the invoked error handler allows \fI\%MPI_Testsome\fP to return to
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the caller, the value \fBMPI_ERR_IN_STATUS\fP will be returned in the C
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and Fortran bindings.
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.sp
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\fBSEE ALSO:\fP
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.INDENT 0.0
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.INDENT 3.5
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.INDENT 0.0
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.IP \(bu 2
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\fI\%MPI_Comm_set_errhandler\fP
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.IP \(bu 2
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\fI\%MPI_File_set_errhandler\fP
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.IP \(bu 2
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\fI\%MPI_Test\fP
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.IP \(bu 2
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\fI\%MPI_Testall\fP
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.IP \(bu 2
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\fI\%MPI_Testany\fP
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.IP \(bu 2
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\fI\%MPI_Wait\fP
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.IP \(bu 2
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\fI\%MPI_Waitall\fP
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.IP \(bu 2
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\fI\%MPI_Waitany\fP
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.IP \(bu 2
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\fI\%MPI_Waitsome\fP
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.IP \(bu 2
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\fI\%MPI_Win_set_errhandler\fP
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.UNINDENT
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.UNINDENT
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.UNINDENT
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.SH COPYRIGHT
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2003-2025, The Open MPI Community
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.\" Generated by docutils manpage writer.
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