SAS Thread Reading

SAS5 — Tue, 09 Aug 2016 15:36:34 GMT

Hi!

I am new to multi-threading in SAS. I know the table is locked if editing a table but is it possible to read (only) a table at the same time from multiple threads?

Thanks,

Re: SAS Thread Reading

ChrisHemedinger — Tue, 09 Aug 2016 16:02:09 GMT

Have you looked at PROC DS2? Multithreading is baked in. See this blog post for an example.

The benefit is bigger when the process is CPU bound, not I/O bound. But if parallel processing is what you're after, DS2 is worth a look.

Re: SAS Thread Reading

SAS5 — Tue, 09 Aug 2016 16:14:04 GMT

OK! Thanks. I will take a look at DS2.

In the meantime, to give you some context:

we are using ( rsubmit, signoff) to submit multiple threads. Each thread need to access exactly the same table for reading only. Currently we are duplicating each table multiple times for each thread. I was wondering if it is possible to not do this - just read the table directly from different threads at the same time.

Re: SAS Thread Reading

ChrisHemedinger — Tue, 09 Aug 2016 16:27:54 GMT

I don't see why not...

For example, here's a program that we can run in 3 sessions:

proc means data=sashelp.cars(where=(Origin='Asia'));
run;

proc means data=sashelp.cars(where=(Origin='Europe'));
run;

proc means data=sashelp.cars(where=(Origin='USA'));
run;

For such a simple program this is a lot of overhead, but I used EG's Analyze Program feature to create a grid-ready version of the program:

/*----------------------------------------------------------------------------*/
/* There are 3 tasks in this job.                                             */
/* 3 of these tasks can be RSUBMITed.                                         */
/* These 3 tasks used 22 units of time.                                       */
/* The longest task took 10 units of time, 45.5% of total time.               */
/* Based on dependencies, a maximum of 3 tasks might run in parallel.         */
/*----------------------------------------------------------------------------*/
/*----------------------------------------------------------------------------*/
/* This is the user-modifiable number of connect sessions                     */
/*----------------------------------------------------------------------------*/
%let SCAPROC_SESSIONS_COUNT=3;

/*----------------------------------------------------------------------------*/
/* *** Please don't edit anything below this line.                            */
/* *** Regenerate the file if you need to make changes.                       */
/*----------------------------------------------------------------------------*/

/*----------------------------------------------------------------------------*/
/* Enable grid service                                                        */
/*----------------------------------------------------------------------------*/
%let rc=%sysfunc(grdsvc_enable(_all_, resource=SASMKT));

/*----------------------------------------------------------------------------*/
/* This macro starts up the connect sessions                                  */
/*----------------------------------------------------------------------------*/
%macro scaproc_start_sessions(count);
  %do i = 1 %to &count;
    signon sess&i signonwait=no connectwait=no cmacvar=scaproc_signon_&i;
  %end;
%mend scaproc_start_sessions;

/*----------------------------------------------------------------------------*/
/* Start up our connect sessions.                                             */
/*----------------------------------------------------------------------------*/
%scaproc_start_sessions(&SCAPROC_SESSIONS_COUNT);

/*----------------------------------------------------------------------------*/
/* This function call initializes data structures for our SCAGRID functions.  */
/* We pass in the number of sessions and the number tasks in this job.        */
/*----------------------------------------------------------------------------*/
proc scaproc; startup 3 &SCAPROC_SESSIONS_COUNT; run; 

/*----------------------------------------------------------------------------*/
/* TASK 1 run in rsubmit                                                      */
/*----------------------------------------------------------------------------*/
/* I/O Activity                                                               */
/*----------------------------------------------------------------------------*/
/* DATASET    INPUT  SEQ   created in task 0 #C00003.CARS.DATA                */
/*----------------------------------------------------------------------------*/
/* Symbol activity                                                            */
/*----------------------------------------------------------------------------*/
/* SYMBOL GET task:0 used by subsequent task:no  Name:SYS_IOUSEEE             */
/* SYMBOL GET task:0 used by subsequent task:no  Name:SYSSUMSTACKODS          */
/* SYMBOL GET task:0 used by subsequent task:no  Name:SYSSUMTRACE             */
/*----------------------------------------------------------------------------*/
/* ELAPSED 10                                                                 */
/*----------------------------------------------------------------------------*/
/*----------------------------------------------------------------------------*/
/* Get an available session                                                   */
/*----------------------------------------------------------------------------*/
proc scaproc; getsession 1 "sess"; run; 
%put sess=&sess; 
/*----------------------------------------------------------------------------*/
/* rsubmit for task 1                                                         */
/*----------------------------------------------------------------------------*/
rsubmit &sess sysrputsync=yes cmacvar=scagrid_task_1;
/* task 1 rsubmit */
proc means data=sashelp.cars(where=(Origin='Asia'));
run;


/* for incomplete steps */ ;run; quit; run;
endrsubmit;


/*----------------------------------------------------------------------------*/
/* TASK 2 run in rsubmit                                                      */
/*----------------------------------------------------------------------------*/
/* I/O Activity                                                               */
/*----------------------------------------------------------------------------*/
/* DATASET    INPUT  SEQ   created in task 0 #C00003.CARS.DATA                */
/*----------------------------------------------------------------------------*/
/* Symbol activity                                                            */
/*----------------------------------------------------------------------------*/
/* SYMBOL GET task:0 used by subsequent task:no  Name:SYS_IOUSEEE             */
/* SYMBOL GET task:0 used by subsequent task:no  Name:SYSSUMSTACKODS          */
/* SYMBOL GET task:0 used by subsequent task:no  Name:SYSSUMTRACE             */
/*----------------------------------------------------------------------------*/
/* ELAPSED 6                                                                  */
/*----------------------------------------------------------------------------*/
/*----------------------------------------------------------------------------*/
/* Dependencies                                                               */
/* Highest task depended on: 0                                                */
/*----------------------------------------------------------------------------*/
/*----------------------------------------------------------------------------*/
/* Get an available session                                                   */
/*----------------------------------------------------------------------------*/
proc scaproc; getsession 2 "sess"; run; 
%put sess=&sess; 
/*----------------------------------------------------------------------------*/
/* rsubmit for task 2                                                         */
/*----------------------------------------------------------------------------*/
rsubmit &sess sysrputsync=yes cmacvar=scagrid_task_2;
/* task 2 rsubmit */
proc means data=sashelp.cars(where=(Origin='Europe'));
run;


/* for incomplete steps */ ;run; quit; run;
endrsubmit;


/*----------------------------------------------------------------------------*/
/* TASK 3 run in rsubmit                                                      */
/*----------------------------------------------------------------------------*/
/* I/O Activity                                                               */
/*----------------------------------------------------------------------------*/
/* DATASET    INPUT  SEQ   created in task 0 #C00003.CARS.DATA                */
/* FILE       OUTPUT       created in task 3 /sas/work/SAS_work038D0000658E_misci01p/#LN00023  */
/*----------------------------------------------------------------------------*/
/* Symbol activity                                                            */
/*----------------------------------------------------------------------------*/
/* SYMBOL GET task:0 used by subsequent task:no  Name:SYS_IOUSEEE             */
/* SYMBOL GET task:0 used by subsequent task:no  Name:SYSSUMSTACKODS          */
/* SYMBOL GET task:0 used by subsequent task:no  Name:SYSSUMTRACE             */
/*----------------------------------------------------------------------------*/
/* ELAPSED 6                                                                  */
/*----------------------------------------------------------------------------*/
/*----------------------------------------------------------------------------*/
/* Dependencies                                                               */
/* Highest task depended on: 0                                                */
/*----------------------------------------------------------------------------*/
/*----------------------------------------------------------------------------*/
/* Get an available session                                                   */
/*----------------------------------------------------------------------------*/
proc scaproc; getsession 3 "sess"; run; 
%put sess=&sess; 
/*----------------------------------------------------------------------------*/
/* rsubmit for task 3                                                         */
/*----------------------------------------------------------------------------*/
rsubmit &sess sysrputsync=yes cmacvar=scagrid_task_3;
/* task 3 rsubmit */
proc means data=sashelp.cars(where=(Origin='USA'));
run;

;*';*";*/;quit;run; /*Quote and Comment Killer*/

/* for incomplete steps */ ;run; quit; run;
endrsubmit;


/*----------------------------------------------------------------------------*/
/* This macro issues waitfors and signoffs for our sessions.                  */
/*----------------------------------------------------------------------------*/
%macro scagrid_waitfors(count);
  %do i = 1 %to &count;
    waitfor sess&i;
    signoff sess&i;
  %end;
%mend scagrid_waitfors;

/*----------------------------------------------------------------------------*/
/* Wait for and sign off all sessions.                                        */
/*----------------------------------------------------------------------------*/
%scagrid_waitfors(&SCAPROC_SESSIONS_COUNT);

/*----------------------------------------------------------------------------*/
/* Termination for our  SCAGRID functions.                                    */
/*----------------------------------------------------------------------------*/
proc scaproc; shutdown; run;

/*----------------------------------------------------------------------------*/
/* All done.                                                                  */
/*----------------------------------------------------------------------------*/

Re: SAS Thread Reading

SAS5 — Tue, 09 Aug 2016 17:42:01 GMT

Thank you! I will try it.

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