Loading doc/src/Howto_library.rst +25 −0 Original line number Diff line number Diff line Loading @@ -20,6 +20,31 @@ and C and Python codes which show how a driver code can link to LAMMPS as a library, run LAMMPS on a subset of processors, grab data from LAMMPS, change it, and put it back into LAMMPS. Thread-safety ------------- LAMMPS has not initially been conceived as a thread-safe program, but over the years changes have been applied to replace operations that collide with creating multiple LAMMPS instances from multiple-threads of the same process with thread-safe alternatives. This primarily applies to the core LAMMPS code and less so on add-on packages, especially when those packages require additional code in the *lib* folder, interface LAMMPS to Fortran libraries, or the code uses static variables (like the USER-COLVARS package. Another major issue to deal with is to correctly handle MPI. Creating a LAMMPS instance requires passing an MPI communicator, or it assumes the MPI\_COMM\_WORLD communicator, which spans all MPI processor ranks. When creating multiple LAMMPS object instances from different threads, this communicator has to be different for each thread or else collisions can happen, or it has to be guaranteed, that only one thread at a time is active. MPI communicators, however, are not a problem, if LAMMPS is compiled with the MPI STUBS library, which implies that there is no MPI communication and only 1 MPI rank. Provided APIs ------------- The file src/library.cpp contains the following functions for creating and destroying an instance of LAMMPS and sending it commands to execute. See the documentation in the src/library.cpp file for Loading doc/txt/Howto_library.txt +23 −0 Original line number Diff line number Diff line Loading @@ -28,6 +28,29 @@ and C and Python codes which show how a driver code can link to LAMMPS as a library, run LAMMPS on a subset of processors, grab data from LAMMPS, change it, and put it back into LAMMPS. Thread-safety :h4 LAMMPS has not initially been conceived as a thread-safe program, but over the years changes have been applied to replace operations that collide with creating multiple LAMMPS instances from multiple-threads of the same process with thread-safe alternatives. This primarily applies to the core LAMMPS code and less so on add-on packages, especially when those packages require additional code in the {lib} folder, interface LAMMPS to Fortran libraries, or the code uses static variables (like the USER-COLVARS package. Another major issue to deal with is to correctly handle MPI. Creating a LAMMPS instance requires passing an MPI communicator, or it assumes the MPI_COMM_WORLD communicator, which spans all MPI processor ranks. When creating multiple LAMMPS object instances from different threads, this communicator has to be different for each thread or else collisions can happen, or it has to be guaranteed, that only one thread at a time is active. MPI communicators, however, are not a problem, if LAMMPS is compiled with the MPI STUBS library, which implies that there is no MPI communication and only 1 MPI rank. Provided APIs :h4 The file src/library.cpp contains the following functions for creating and destroying an instance of LAMMPS and sending it commands to execute. See the documentation in the src/library.cpp file for Loading Loading
doc/src/Howto_library.rst +25 −0 Original line number Diff line number Diff line Loading @@ -20,6 +20,31 @@ and C and Python codes which show how a driver code can link to LAMMPS as a library, run LAMMPS on a subset of processors, grab data from LAMMPS, change it, and put it back into LAMMPS. Thread-safety ------------- LAMMPS has not initially been conceived as a thread-safe program, but over the years changes have been applied to replace operations that collide with creating multiple LAMMPS instances from multiple-threads of the same process with thread-safe alternatives. This primarily applies to the core LAMMPS code and less so on add-on packages, especially when those packages require additional code in the *lib* folder, interface LAMMPS to Fortran libraries, or the code uses static variables (like the USER-COLVARS package. Another major issue to deal with is to correctly handle MPI. Creating a LAMMPS instance requires passing an MPI communicator, or it assumes the MPI\_COMM\_WORLD communicator, which spans all MPI processor ranks. When creating multiple LAMMPS object instances from different threads, this communicator has to be different for each thread or else collisions can happen, or it has to be guaranteed, that only one thread at a time is active. MPI communicators, however, are not a problem, if LAMMPS is compiled with the MPI STUBS library, which implies that there is no MPI communication and only 1 MPI rank. Provided APIs ------------- The file src/library.cpp contains the following functions for creating and destroying an instance of LAMMPS and sending it commands to execute. See the documentation in the src/library.cpp file for Loading
doc/txt/Howto_library.txt +23 −0 Original line number Diff line number Diff line Loading @@ -28,6 +28,29 @@ and C and Python codes which show how a driver code can link to LAMMPS as a library, run LAMMPS on a subset of processors, grab data from LAMMPS, change it, and put it back into LAMMPS. Thread-safety :h4 LAMMPS has not initially been conceived as a thread-safe program, but over the years changes have been applied to replace operations that collide with creating multiple LAMMPS instances from multiple-threads of the same process with thread-safe alternatives. This primarily applies to the core LAMMPS code and less so on add-on packages, especially when those packages require additional code in the {lib} folder, interface LAMMPS to Fortran libraries, or the code uses static variables (like the USER-COLVARS package. Another major issue to deal with is to correctly handle MPI. Creating a LAMMPS instance requires passing an MPI communicator, or it assumes the MPI_COMM_WORLD communicator, which spans all MPI processor ranks. When creating multiple LAMMPS object instances from different threads, this communicator has to be different for each thread or else collisions can happen, or it has to be guaranteed, that only one thread at a time is active. MPI communicators, however, are not a problem, if LAMMPS is compiled with the MPI STUBS library, which implies that there is no MPI communication and only 1 MPI rank. Provided APIs :h4 The file src/library.cpp contains the following functions for creating and destroying an instance of LAMMPS and sending it commands to execute. See the documentation in the src/library.cpp file for Loading
