2.1.4 Obtaining parallel processes information

Products: Abaqus/Standard Abaqus/Explicit

References

Overview

Utility routines GETNUMCPUS and GETRANK can be called from any Abaqus/Standard user subroutine. GETNUMCPUS returns the number of MPI processes, and GETRANK returns the rank of the MPI process from which the function is called. For example, in a hybrid MPI and thread parallel execution scheme, multiple threads may all return the rank of their parent MPI process (see “Parallel execution in Abaqus/Standard,” Section 3.5.2 of the Abaqus Analysis User's Guide).

Utility routines VGETNUMCPUS and VGETRANK can be called from any Abaqus/Explicit user subroutine in a domain-parallel run. VGETNUMCPUS provides the number of processes used for the parallel run, and VGETRANK provides the individual process rank (see “Parallel execution in Abaqus/Explicit,” Section 3.5.3 of the Abaqus Analysis User's Guide).

Utility routine GETNUMTHREADS can be called from any Abaqus user subroutine. It returns the number of threads in a process. In a hybrid parallel execution mode, there will be several Abaqus MPI processes, each having several threads.

You can determine the ID of the thread you are in by calling the utility function get_thread_id. The returned ID is an integer that Abaqus assigns to each of its threads. The main thread will have the ID=0, and each subsequent thread will have an ID of 1, 2, 3, 4, ..., N. This function can be called from any Abaqus user subroutine and from both the FORTRAN and C/C++ codes.

Utility function GETCOMMUNICATOR can be called from any Abaqus user subroutine. GETCOMMUNICATOR returns a communicator that Abaqus defines for its worker processes, similar to MPI_COMM_WORLD. In FORTRAN its type is an INTEGER; in C++ this function is called get_communicator() and returns a value of the type MPI_Comm. The communicator thus obtained can be used for subsequent MPI communication routines. In a nonparallel run, when the MPI subsystem is not initialized, communicators do not exist and both GET_COMMUNICATOR() and get_communicator() will return 0. Another way of testing is to call the MPI_Initialized(flag) function. This function will set the flag to 1 if MPI has been initialized.

`GETNUMCPUS` and `VGETNUMCPUS` (obtain the number of processes)

Interface

         CALL GETNUMCPUS( NUMPROCESSES )
         CALL VGETNUMCPUS( NUMPROCESSES )
         ...

Variable returned from the utility routine

NUMPROCESSES

Number of processes specified for the analysis.

`GETRANK` and `VGETRANK` (obtain the process number)

Interface

         CALL GETRANK( KPROCESSNUM )
         CALL VGETRANK( KPROCESSNUM )
         ...

Variable returned from the utility routine

KPROCESSNUM

Process number or rank. A process number is either zero or a positive integer.

`GETNUMTHREADS` (obtain the number of threads)

Interface

FORTRAN:
#include <SMAAspUserSubroutines.hdr>

         integer numThreads 
         numThreads = GETNUMTHREADS()

C++:
         #include <SMAAspUserSubroutines.h>

         int numThreads = GETNUMTHREADS();

get_thread_id

Interface

FOTRAN:
#include <SMAAspUserSubroutines.hdr>    

         INTEGER myThreadID

         myThreadID = get_thread_id()

C++:
         #include <SMAAspUserSubroutines.h>

         int myThreadID = get_thread_id()

Variable returned from the utility routine

thread_id

Current thread ID, an integer.

GETCOMMUNICATOR (FORTRAN)

Interface

#include <SMAAspUserSubroutines.hdr>

         integer ABA_COMM_WORLD

         ABA_COMM_WORLD = GETCOMMUNICATOR()

         if (ABA_COMM_WORLD.ne.0) then
             ...do some parallel work, using MPI ...
         else
             ...do some work in a single process ...
         end if

Variable returned from the utility routine

INTEGER

Communicator handle identifier of type INTEGER. In a non-MPI run, the value returned will be zero.

get_communicator (C++)

Interface

#include <SMAAspUserSubroutines.h>

         MPI_Comm ABA_COMM_WORLD = get_communicator()

         if (ABA_COMM_WORLD) {
            ... do some parallel work, using MPI ... 
         }
         else{
             ...do some work in a single process ...
         }

Variable returned from the utility routine

MPI_Comm

Communicator handle of type MPI_Comm. In a non-MPI run, the value returned will be zero.