THREADS Subcommand (SET command)

The THREADS subcommand specifies the number of threads that multithreaded procedures use when calculating results. By default, IBM® SPSS® Statistics uses an internal algorithm to determine the number of threads for a particular computer. You can change this setting, but the default (THREADS=AUTO) will often provide the best performance. The default also appears as the recommended setting when you run the SHOW command.

In local analysis mode, any changes to the setting persist across sessions until you explicitly change the setting to a different value. In distributed analysis mode (available with IBM SPSS Statistics Server), the setting does not persist across sessions, and the default value is AUTO. Any changes to the setting in distributed analysis mode remain in effect only for the duration of the current session. In distributed analysis mode, the maximum number of threads can be limited by the administrator.

Using more than one thread is relevant only if your computer has multiple processors or each processor has multiple cores. Also, this setting affects only selected procedures that take advantage of it. These are:

• CORRELATIONS
• CSCOXREG
• CSLOGISTIC
• CSORDINAL
• CSSELECT
• DISCRIMINANT
• FACTOR
• NOMREG
• PARTIAL CORR
• REGRESSION
• SIMRUN
• SORT CASES

Note: PRESERVE and RESTORE do not operate on this subcommand.