How to Turn Off Multithreading in LabVIEW

Issue Details

Why Would I Want to Turn Off Multithreading in LabVIEW?

Solution

There are two reasons why you would want to turn off multithreading:

1. You are using an older/slower computer
2. Your VIs inexplicably crash

Multithreading can cause LabVIEW to run slower on older computers due to their limited resources. In this case, turning multithreading off improves the performance of LabVIEW and the performance of other running applications. 

Today multithreading is turned off largely for debugging VIs that crash for no reason. VIs that use ActiveX features or dlls that are incorrectly identified as threadsafe can crash because the ActiveX features or the dll corrupted the computer's memory. If turning off multithreading makes the VI stable, then your focus can be placed on these parts of the code. If you have access to the source code of the dll or ActiveX components, you can make the corrections yourself. If the dll or ActiveX components are from a third party, then the dlls can be set to run in the user interface thread, but the ActiveX components may require that LabVIEW not be restored to multithreading mode.

In LabVIEW 8.2 or later, the Performance and Disk tab in the Options dialog box no longer exists. To turn off multithreading you have to manually add an entry into the LabVIEW .ini file. Add ESys.StdNParallel=0 to the .ini file to disable multithreading in LabVIEW.

Additional Information

Earlier than LabVIEW 8.2 You can turn off multithreading by opening LabVIEW and going to Tools»Options»Performance and Disk»Run with Multiple Threads. You will have to restart LabVIEW in order for the changes to take effect.