HP-MPI provides support for dynamic process management, specifically the
spawn, join, and connecting of new processes. MPI_Comm_spawn() starts MPI processes and establishes communication
with them, returning an intercommunicator.
MPI_Comm_spawn_multiple() starts several different binaries (or the same binary
with different arguments), placing them in the same comm_world and
returning an intercommunicator. The MPI_Comm_spawn() and MPI_Comm_spawn_multiple() routines provide an interface between MPI and the runtime
environment of an MPI application.
MPI_Comm_accept() and MPI_Comm_connect() along with MPI_Open_port() and MPI_Close_port() allow two independently run MPI applications to connect
to each other and combine their ranks into a single communicator.
MPI_Comm_join() allows two ranks in independently run MPI applications
to connect to each other and form an intercommunicator given a socket
connection between them.
Each collection of spawned ranks only talks to the others
through the comm daemons via sockets. Even if two comm_worlds are on the same host, the ranks within one comm_world will talk among themselves through shared memory, but
ranks between the two comm_worlds will not talk to each other through shared memory.
Spawn functions supported in HP MPI:
MPI_Comm_spawn_multiple()
Keys interpreted in the info argument to
the spawn calls:
host
-- We accept standard host.domain strings and start the ranks on
the specified host. Without this key, the default is to start on
the same host as the root of the spawn call.
wdir -- We accept /some/directory
strings.
path -- We accept /some/directory:/some/other/directory:..
A mechanism for setting arbitrary environment variables for
the spawned ranks is not provided.
Dynamic processes are not supported in HP-MPI V1.0 for Windows.
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