topic Multi Threads processing in SAS Viya in SAS Viya

Multi Threads processing in SAS Viya

mariopellegrini — Wed, 24 Jun 2020 14:57:19 GMT

Goodmorning everyone.

Maybe I didn't understand the mechanism of multi threads.

With this simple test code:

cas mySession sessopts = (caslib = casuser timeout = 1800 locale = "en_US");
libname mycas cas caslib = casuser;

data mycas.ds1; 
x=2; 
put "The # of Threads is " _nthreads_; /* 3 */ 
run;

I get 12 lines instead of 1 and the following message in the log:

NOTES: Running DATA step in Cloud Analytic Services.
Processed intro on _THREADID_ = 11 _NTHREADS_ = 12
Processed intro on _THREADID_ = 4 _NTHREADS_ = 12
Processed intro on _THREADID_ = 2 _NTHREADS_ = 12
Processed intro on _THREADID_ = 5 _NTHREADS_ = 12
Processed intro on _THREADID_ = 3 _NTHREADS_ = 12
Processed intro on _THREADID_ = 1 _NTHREADS_ = 12
Processed intro on _THREADID_ = 12 _NTHREADS_ = 12
Processed intro on _THREADID_ = 7 _NTHREADS_ = 12
Processed intro on _THREADID_ = 10 _NTHREADS_ = 12
Processed intro on _THREADID_ = 8 _NTHREADS_ = 12
Processed intro on _THREADID_ = 9 _NTHREADS_ = 12
Processed intro on _THREADID_ = 6 _NTHREADS_ = 12
NOTE: The ds1 table in caslib CASUSER (sasdemo) has 12 observations and 1 variables.
NOTES: DATA statement used (total processing time):
real time 0.02 seconds
cpu time 0.01 seconds

Why? What is the correct way to load a table into a caslib?
Thank you

Re: Multi Threads processing in SAS Viya

BrunoMueller — Thu, 25 Jun 2020 06:33:30 GMT

The example shows that the DATA Step processing is divided into multiple threads. However your code and the provided log do not fit together.

You are not actually loading any data.

Please provide some more information like:

SAS Viya version
What kind of data do you want to load
Where is this data, on the SAS Viya server or somewhere else

Re: Multi Threads processing in SAS Viya

mario_pelleg — Thu, 25 Jun 2020 09:17:45 GMT

Bruno_SAS, with that code I loaded 12 lines.
Mine is a trivial example to show how to insert a simple 1 row table, in reality it inserts 12. I would like to understand how to make a correct loading.
the trivial datastep is:
mycas.ds1;
x = 2;
run;

Re: Multi Threads processing in SAS Viya

BrunoMueller — Thu, 25 Jun 2020 09:58:00 GMT

Well have a look here https://go.documentation.sas.com/?docsetId=casdspgm&docsetTarget=n183xun5dd4dy5n1x453fw5reu8o.htm&docsetVersion=3.5&locale=en it explains there various process modes.

In your case you need the SINGLE=YES option on the DATA statement like so:

data mycas.sometable / single=yes;
...
run;

Re: Multi Threads processing in SAS Viya

mario_pelleg — Fri, 26 Jun 2020 16:11:20 GMT

thanks for the link to the documentation.
However, I still struggle to understand the meaning.
In practice, for large tables, it is better to do processing using the multi thread. But if I get an incorrect result (the example of 12 lines instead of 1) what do I do with speed?

Re: Multi Threads processing in SAS Viya

BrunoMueller — Mon, 29 Jun 2020 06:27:04 GMT

As asked already earlier, we do need some details on the type of data that you want to load to CAS:

SAS Viya version
What kind of data do you want to load
Where is this data, on the SAS Viya server or somewhere else

Also you should have a look here: https://go.documentation.sas.com/?docsetId=casfun&docsetTarget=n09ssmi0ko8uyfn1022ezo2hv0pm.htm&docsetVersion=3.5&locale=en#n1rdajpahvwz6mn15o3fl6vw99rr