Before SAS 8, when an RSUBMIT statement was executed, the client
session was suspended until processing by the server session had completed.
In SAS 8, MP CONNECT functionality was added, which allows you to
execute RSUBMIT statements asynchronously. When an RSUBMIT is executed
asynchronously, the unit of work is sent to the server session and
control is immediately returned to the client session. The client
session can continue with its own processing or execute RSUBMIT statements
to one or more additional server sessions. Asynchronous RSUBMIT statements
are most useful for longer-running tasks.
MP CONNECT enables you
to perform multiprocessing with SAS by establishing a connection between
multiple SAS sessions and enabling each of the sessions to asynchronously
execute tasks in parallel. You can also merge the results of the
asynchronous tasks into your local execution stream at the appropriate
time. In addition, establishing connections to processes on the same
local computer has been greatly simplified. This enables you to exploit
SMP hardware as well as network resources to perform parallel processing
and easily coordinate all the results into the client SAS session.
You can use MP CONNECT
to start any number of SAS processes that you want to perform in parallel.
SAS processes that are started on a single multiprocessor computer
are independent, unique processes just as they are if they are initiated
on a remote host. For example, under Windows and UNIX, each SAS session
is a separate process that has its own unique SAS WORK library.
Each process also assumes the user context of the parent or of the
user that invoked the original SAS session, and has all the rights
and privileges that are associated with that parent. Under
z/OS,
each SAS session is an MVS BPX address space that inherits the same
STEPLIB and USERID as the client address space. The client's SASHELP
, SASMSG, SASAUTOS, and CONFIG allocations are passed to the new session
as SAS option values.
MP
CONNECT is implemented by executing an RSUBMIT statement and the CONNECTWAIT=NO
option. This method causes
SAS/CONNECT to submit a task to a server
session for processing and return control immediately to the client
session so that you can start other tasks in the client session or
in other server sessions. For details about the CONNECTWAIT= option,
see
RSUBMIT Statement and Command .