Using Compute Services

MP CONNECT

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 Syntax for the RSUBMIT Statement and Command.

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