Make A step in a SAS macro timeout after a set interval

2
votes

I'm on SAS 9.1.3 (on a server) and have a macro looping over an array to feed a computationally intensive set of modelling steps which are appended out to a table. I'm wondering if it is possible to set a maximum time to run for each element of the array. This is so that any element which takes longer than 3 minutes to run is skipped and the next item fed in.

Say for example I'm using a proc nlin with a by statement to build separate models per class on a large data set, and one class is failing to converge; how do I skip over that class?

Bit of a niche requirement, hope someone can assist!

2
macrossas

2 Answers

2
votes

In general, SAS is running in a linear manner. So you cannot write a step to monitor another step in the same program. What you could do is run your code in a SAS/CONNECT session and monitor it with the process that started the session. That's not trivial and the how to is beyond the scope of Stack Overflow.

For a data step, use the datetime() function to get the current system date and time. This is measured in seconds. You can check the time inside your data step. Stop a data step with the stop; statement.

Now you specifically asked about breaking a specific step inside a PROC. That must be implemented in the PROC by the SAS developer. If it is possible, it will be documented in the procedure's documentation. View SAS documentation at http://support.sas.com/documentation/.

For PROC NLIN, I do not think there is a "break after X" parameter. You can use the trace parameters to track model execution to see what it hanging up. You can then work on changing the convergence parameters to attempt to speed up slow, badly converging, models.

2
votes

The only approach I can think of here would be to rewrite your code so that it runs each by group separately from the rest, in one or more SAS/CONNECT sessions, have the parent session kill each one after a set timeout, and then recombine the surviving output.

As Dom and Joe have pointed out, this is not a trivial task, but it's possible if you're sufficiently keen on learning about that aspect of SAS. A good place to get started for this sort of thing would be this page:

http://support.sas.com/rnd/scalability/tricks/connect.html

I was able to use the examples there and elsewhere as the basis of a simple parallel processing framework (in SAS 9.1.3, coincidentally!), but there are many details you will need to consider. To give you an idea of the sorts of adventures in store if you go down this route:

  • Learning how to sign on to your server via SAS/CONNECT within whatever infrastructure you're using (will the usual autoexec file work? What invocation options do you need to use?)
  • Explaining to your sysadmin/colleagues why you need to run multiple processes in parallel
  • Managing asynchronous sessions
  • Syncing macro variables, macro definitions, libraries and formats between sessions
  • Obscure bugs (I wasn't able to use the usual option for syncing libraries and had to roll my own via call execute...)

One could write a (lengthy) SUGI paper on this topic, and I'm sure there are plenty of them out there if you look around.