XWait and XSync not behaving correctly - sas

Question

I am running SAS 9 on Windows Vista. I am using system Commands to execute some Python code in some nested macros that are passing different parameters to Python each time. Im using the XSYNC and XWAIT options in SAS.
My understanding of this is that these two options should make SAS pause until the Python script has completed running. With this option the Python Command Prompt window closes when the code completes execution and I am then prompted to type EXIT, which is what you would expect.
However, when I use NOXWAIT XSYNC the SAS code passes each Python invocation, kicks it off and keeps running. After a few minutes I have hundreds of Command Prompt windows open all trying to run at the same time.
What am I doing wrong? As a work around I have tried using x 'EXIT' and call system ('EXIT') to close the windows administrator command prompt window down but this does not seem to be being passed to the window, even though the exit command is in a separate data null step to the one that calls the Python code.
Any ideas?
Here is code I'm using:
data _null_;
x 'cd C:\Python33';
x 'start test.py';
run;
data _null_;
call system ('exit');
run;
What happens is two Command Prompt windows open. The second one is the Python script running. This closes itself and I am left with the administrator window. I have tried putting an x command of 'Exit'; in the first data null step, but this has not worked.

Answer 1

XSYNC tells SAS to execute an external command synchronously, meaning SAS pauses until the command completes. You would use NOXSYNC only in very specific applications.
XWAIT tells SAS to wait for you to explicitly exit the window running the command. In most cases, you would want to use NOXWAIT.
The problem you describe suggests to me that your Python commands are not properly terminated. Sorry, nut I don't know Python. But consider putting your Python statements in a script file, which closes itself with an exit command, or adding an exit command to the SAS call, something like:
data _null_;
call system('python-command;exit');
run;
If this does not help, revise your question and show the complete SAS data step code you are using. Note, using a second X command to push an "exit" statement will not work; it must be part of the initial call.